Spacefaring America

27 - Where DOE should focus its energies

2009-08-12T17:03:00Z

Dr. Steven Chu, U.S. Secretary of Department of Energy (DOE), started a Facebook page to open a new avenue for public input on energy topics. On his "Discussions" page, I started a discussion topic titled: "DOE's fundamental responsibilities." Here is what I wrote.

DOE’s fundamental responsibility is to assure that America has sufficient and affordable energy supplies. As the era of easy energy (oil, coal, and natural gas) ends in the coming decades, DOE’s primary mission at this time should be to define and implement a sustainable energy transition strategy that will undertake building such new, industrial-scale sustainable energy sources as are needed to avoid U.S. energy scarcity and the real potential of energy scarcity in the decades ahead.

What DOE should now do:

1. Prepare, in short order, a preliminary forecast of U.S. energy needs and easy energy supplies, both domestic and imported, through the end of the century to identify to what extent new sustainable energy sources must be brought into operation and by when. This forecast should deal realistically with the rising U.S. population and U.S. per capita energy needs through the end of the century.

2. Assess the realistic potential of conventional nuclear energy and terrestrial renewables—hydroelectric, geothermal, wind, ground solar electric, and land biomass—to fill shortfalls in dispatchable electrical power generation capacity and annual fuels production that will develop as easy energy supplies, both domestic and imported, diminish in the coming decades.

3. Identify the needed additional sustainable energy sources, capable of industrial-scale production, that are now ready for commercial engineering development and should be pursued to ensure that U.S. energy supply shortages or scarcity do not occur.

Until DOE has completed these three actions, it is not known if it is establishing the U.S. energy policies that are needed to ensure sufficient and affordable U.S. energy supplies in the coming decades. This, not climate change, remains DOE’s primary responsibility.

In collecting information for my white paper, "The End of Easy Energy and What to Do About It," the U.S. Department of Energy's Energy Information Administration (EIA) was a primary data source. When I started to conduct my assessment of the future energy supply situation that led, eventually, to the paper, I was surprised that long-range energy forecasting to the end of the century was not a part of the EIA's standard projections. Their forecasting went out only about 20 years, currently to about 2030. This raised a big red flag. Why such a short-term focus? What are the implications of this?

My energy assessment led me to the conclusion that, as the title infers, we are at the end of the era of easy energy—conventional oil, coal, and natural gas. Reaching this conclusion was the result of the fairly straightforward collection of per capita energy use statistics, population growth projections, and official estimates of U.S. and world proved energy reserves and additional potentially recoverable resources. Rapid world per capita energy increases, consistent with our western style of living, can only be expected to dramatically increase the needed world energy production capacity. Simply put, the addition of 5-6 billion modern energy consumers by 2100 will lead to a needed 3.5X increase in needed world energy production capacity. At this rate of growth, world easy energy resources will become exhausted before 2100. I did not see this mentioned as a possibility in any of the EIA publications I reviewed. (Hopefully, I just missed it.)

Joel Barker is one of my favorite authors. A futurist, he has written on the concept of paradigms. A paradigm, using my words, is a psychological framework for living and decision making. The paradigm provides us a set of rules and we use the rules to decide what actions to take or not take to comfortably live. Eventually, the rules will fail to successfully guide our living choices. Problems without apparent solutions will accumulate and paradigm “shifters”—to follow Barker’s line of reasoning—will experiment to identify a new set of rules—a new paradigm—by which we will then come to live. This happens all of the time.

Easy energy has been western civilization’s successful paradigm for nearly 16 decades, since the 1860’s. Many experts believe that we are reaching the end of increasing conventional oil production—peak oil—and the peaks in coal and natural gas production will follow in the coming decades. What is coming about is that nearly 5 billion people are trying to emulate the success of the U.S. in dramatically raising their standard of living by increasing their per capita energy supplies. The difference is that the U.S. (and Western Europe, Japan, South Korea, etc.) did this as conventional oil production was still growing. The world is now trying to do this on the downhill side of the conventional oil production curve—after the peak is reached. This will increase demand for coal and natural gas to fill the shortfalls in oil with new oil replacements. This will lead to the earlier exhaustion of coal and natural gas resources, leading to shortages and, then, scarcity of easy energy worldwide. When this happens, as emphasized in the white paper, the world and the U.S. will be living on whatever sustainable energy supplies are available. Today, that is quite limited.

From the focus of their energy publications, I am led to believe that the DOE largely remains in an easy energy paradigm where the solution to increasing world energy demands is to increase easy energy production. In this paradigm, forecasting focuses on the proved reserves of the energy companies. If the commercial companies have a good 20 years of proved reserves and were investing in adding production capacity to meet growing demand, then there was little reason to look beyond 20 years or so. This is what has been done for two generations.

But we now understand, from experience, that this is shortsighted. Energy forecasters in the U.S. in the 1930’s saw a reduction in new discoveries of conventional oil in the U.S., even though domestic production was increasing. They correctly anticipated peak domestic oil production in the decades ahead and saw that early U.S. Government action to secure new foreign resources was needed. The British had determined that vast (at the time) oil fields were easily exploitable in the Mideast. When British influence in the area diminished during World War II, President Roosevelt exerted U.S. political influence to secure U.S. oil company involvement in opening these new oil fields. In the 1950’s formal projections of peak U.S. conventional oil production were made for the early 1970’s. In the 1970’s, the same was done for the world. This time, however, proactive Government action to prevent future U.S. energy shortages, such as happened in the 1940’s in the middle of World War II, did not happen.

Today, a comparable situation is developing with peak world conventional oil, coal, and natural gas production. Serious attention is needed to plan and successfully execute a transition to sustainable energy sources—particularly second-generation renewable energy sources. But this does not appear to be on the radar screen of the Secretary of Energy and his staff. His focus is on global climate change and first-generation renewables—renewables that lack the potential to provide a significant share of U.S. and world future energy supplies.

When Dr. Chu opened a Face Book page with the ability to initiate discussion, I thought it was a good idea to raise this important energy policy and planning issue. I did this on July 22, 2009. Now, several weeks later, only one person has responded with a comment and it was not the Secretary of Energy or a member of his staff.

26 - Getting behind space solar power

2009-08-10T12:39:00Z

Almost two years ago, I started to put space solar power into perspective in terms of how important this will be to assuring America's energy security. In the May 4, 2009, issue of The Space Review, I published the essay, The Vital Need for America to Develop Space Solar Power. (A print version, with a couple of minor changes, is available on my web site here.) This essay brought together several pro-human spacefaring and American energy security arguments I have raised through this blog and other recent publications available on my web site. To briefly summarize:

America’s future energy security is at risk because insufficient emphasis has been placed on developing new sustainable energy supplies to replace oil, coal, and natural gas as these resources are depleted in the coming decades. Energy scarcity is a very real possibility that should not be easily dismissed.
Current nuclear fission energy and terrestrial renewable energy sources (hydroelectric, geothermal, wind, ground solar energy, and land biomass converted fuels) lack the capacity, even under optimistic conditions, to meet growing U.S. energy needs—they are even inadequate to meet current U.S. needs. Public expectations that such green energy sources will easily replace oil, coal, and natural gas are creating a false sense of future American energy security that will only increase the potential of future energy scarcity.
To provide baseload, dispatchable electrical power generation, space solar power is the only large-scale electrical power generation option, not currently being pursued, that is ready for commercial engineering development. The two primary alternatives--methane hydrates and advanced nuclear energy (e.g., fusion)--are not yet ready for commercial engineering development.
A well-reasoned and executable U.S. energy policy must squarely address the need to aggressively develop new U.S. sustainable energy sources to avoid potential energy scarcity. A key element of the execution of this policy should be to start the commercial development of space solar power(SSP) as a hedge against potential future national energy scarcity.

The American pro-human spacefaring community should seize upon these circumstances to advocate for U.S. Government policy support for both the start of the commercial development of SSP. Although there is a reasonable expectation that much of the deployment and servicing of SSP platforms will be undertaken robotically, substantial human involvement will still be required. Concurrent with the development of SSP will be the need to advance American spacefarer capabilities throughout the Earth-Moon frontier. Starting the commercial development of SSP as a hedge against future energy scarcity and advancing American human spacefaring capabilities become linked with a synergy that benefits America both by increasing its future energy security and starting its transformation into a true spacefaring nation. Inaction or the weak advocacy by the American pro-human spacefaring community in favor of the commercial development of SSP is inexcusable!

25 - Space Solar Power and America's Energy Future (Part 6)

2008-12-14T14:25:00Z

Series recap:

This series began, over a year ago, at the conclusion of the National Security Space Office’s (NSSO) 2007 ad hoc study of space-based solar power or, as most refer to it, space solar power (SSP). My primary involvement with the NSSO study focused on the spacefaring logistics necessary to support a demonstration SSP platform. As such, it is appropriate to note that I do not profess to be an expert on the technologies that form the basis of the SSP system or those of competing alternative energy sources.

While attending the study’s summary conference in September 2007, several presenters focused on the underlying rationale for the SSP study—to address the world’s growing energy insecurity. Neither the study nor the comments of these presenters were breaking new ground, however. Such rationale had been at the core of the SSP arguments since the 1970’s. Regardless, it was apparent that while the passion for SSP was reemerging, the fact-driven case arguing for SSP had not yet emerged. To this end I turned my attention with the start of this series on Space Solar Power and America’s Energy Future.

In Part 5, I reported on my initial efforts to address the first priority of energy sufficiency and energy availability. I focused on non-renewable oil, coal, and natural gas—what I refer to as “easy energy”—because these energy sources account for the vast majority of the United States’ and the world’s energy supplies.

My initial research quickly brought to my attention the fact that most forward-looking energy sufficiency and availability projections only looked 20-30 years into the future. Clearly, this was insufficient from an energy policy planning perspective. I pushed my planning horizon out to 2100. When I examined the sufficiency of easy energy with this time horizon, it was very clear that even optimistic estimates of oil, coal, and natural gas resources would not get the U.S. and the world to 2100 with stable energy sources. By 2100, the U.S. and the world would, necessarily, be running primarily on sustainable energy sources. Part 5 ended with these conclusions:

1. Growth in world per capita energy needs, spurred by expectations of an improving standard of living as a sign of political and economic success, will dramatically increase needed energy supplies throughout this century.

2. An energy planning horizon of 20-30 years, when non-renewable hydrocarbon fuels will continue to provide the vast majority of the world's energy, neither adequately anticipates nor responds to the world's energy situation later this century.

3. By the end of the century, the world will need to fully replace nearly all production of non-renewable hydrocarbons with renewable or nuclear alternatives, with a total world energy production capacity 3-4 times that of today.

4. Undertaking a transformation from primarily non-renewable to primarily renewable/nuclear energy production is a necessity, if this model's projections of easy energy reserves are reasonably accurate.

5. The stage is now set to compare space solar power against terrestrial renewable and nuclear energy sources, not in terms of economics, but in terms of the magnitude of the energy needed to meet future world needs.

Part 5 set the stage for the comparison of space solar power against terrestrial renewable and nuclear energy sources—what are referred to as sustainable energy. This effort was undertaken in the form of a stand-alone white paper that updated the previous efforts before continuiung with the comparison. This has now been completed with a 126-page white paper titled: “The End of Easy Energy and What to Do About It.” This white paper is available on my web site on the spacefaring resources page. The Introduction, Preface, and Executive Summary of the paper are excerpted below. A two-page point paper summarizing the white paper, “America’s Energy Future is at Risk without Space Solar Power,” is also available.

The two major points drawn from this effort are:

1. By the end of the century, if not decades earlier, almost all of the United States and the world’s energy must come from sustainable energy sources.

2. If the United States is to maintain close to its current per capita energy availability—the key to its standard of living and economic prosperity—then SSP will be needed to fill the shortfall left by terrestrial sustainable energy sources. Developing SSP is a necessity that should not be delayed.

===== Excerpt =====

The End of Easy Energy and What to Do About It

James Michael Snead, P.E.

Introduction

Food, shelter, water, security, and energy are fundamental human needs. The primary benefit of human civilization, and a principle purpose of government, is to organize human efforts to reliably supply these fundamental needs.

On-demand energy in the form of electricity and modern fuels is the lifeblood of modern civilization. It amplifies human efforts enabling humans to produce more, travel farther, communicate more broadly and quickly, and live at a higher standard of living than is possible through human efforts alone. Temporarily disrupt the supply of energy and the technological clockwork of modern civilization quickly grinds to a halt. Put forth the prospect of the long-term disruption of energy supplies and the consequences are deemed so undesirable that nations will go to war to secure their energy supplies.

Today, at the beginning of the 21st century, the world is beginning the fifth, and likely final, century of easy non-renewable energy. Beginning in Europe in the early 1600’s, the growth of civilization—in particular, the concentration of population in urban areas in cold climates—outstripped the affordable renewable energy supply of wood. Coal, recognized from the beginning as a non-renewable resource, began to be mined to fill the gap between consumer demand and affordable renewable energy supplies. Technology advancement in mining, especially the introduction of the first steam engines to pump water from deep mines, provided coal producers with a production cost advantage over wood harvesting. As a result, the era of “easy,” non-renewable energy began, expanding to include oil and natural gas in the mid-1800’s.

The benefits of easy energy are all around us. Easy energy has literally powered the rise of modern civilization by increasing human productivity and, especially, freeing a large percentage of the population from the toil of pre-modern agriculture and primitive biomass energy recovery (e.g., chopping wood and gathering fallen dead wood). Those nations that have prevailed in the use of easy energy are today’s leading nations. Developing nations, containing billions of people still living in energy impoverishment, clearly recognize the linkage between modern energy availability and economic development. Quite understandably, they are increasing their supplies of easy energy to stimulate economic development, raise their standard of living, and increase the social and political stability of their nations.

The readily apparent consequence of this on-going expansion of modern civilization is that the worldwide demand for easy energy is outstripping the resources of nature’s gifts of oil, coal, and natural gas, just as happened with wood four centuries earlier. Consequently, these non-renewable energy resources will likely be exhausted this century—perhaps within the lifetime of today’s young adults, certainly within the lifetime of today’s young children.

Having foreknowledge of this coming end of easy energy, what path should the United States and the world prepare to follow? Should a primary reliance on non-renewable easy energy be blindly followed without any substantial and determined investment in developing replacement sources of sustainable energy? We have comparable sustainable objectives for food, water, housing, and security. Why not for energy?

This paper’s exploration of our shared energy future is based on the presumption that the United States and most other nations desire assured, sustainable energy supplies with, if possible, substantial energy independence. Delving into the specifics necessary to understand the implications of what it will take to achieve this desired energy future, this paper aims to identify what sustainable energy production resources will be needed. For the United States, this paper’s objective is to estimate the type and scale of sustainable energy infrastructure needed to provide roughly today’s per capita energy consumption in 2100. For the world, the corresponding objective is to estimate the scale of the sustainable energy infrastructure required to provide, by 2100, the world’s population of 10 billion with a “middle class” per capita energy use comparable to that of Japan, South Korea, and Western Europe.

In the words of futurist Joel Arthur Barker, this paper is a scouting expedition to explore the terrain of the U.S.’s and the world’s energy supply futures. The report coming back is that the world’s forthcoming transformation to a sustainable energy future is, for the United States, an opportunity comparable to the opening of the American west in the 1800’s. In terms of the scale of investment, new business formation, jobs creation, technology advancement, and intellectual property development, transitioning to sustainable energy will be the massive technological and economic powerhouse of the 21st century. Wisely understanding and acting on this opportunity without hesitation should be the strongly-held expectation of all Americans and the clear objective of the energy policy and programs of the next presidential administration. Failing to understand and act will create a disaster where the U.S. literally falls behind the “power curve” of the supply of energy needed to sustain a reasonable standard of living and its role as a great nation.

Preface

This paper focuses on assessing the energy supply situation for the United States and the world in 2100, the end of this century. This has been done to establish a long-term planning horizon where the reader may be comfortable with accepting the argument that the United States’ and the world’s energy supply situations could and, probably, must be significantly different than they are today. However, the reader is cautioned that, from the perspective of transitioning from today’s substantial use of non-renewable oil, coal, and natural gas to a future substantial use of sustainable energy sources, the necessity and timeline for this transition will be driven by consumer demand and the rate of depletion of the identified and developed reserves of oil, coal, and natural gas. Hence, by 2100, the United States and the world may have already been decades into the new era of substantial sustainable energy use—not by choice as much as by necessity.

The proper reader perspective, therefore, is to not become comfortable with the notion that we have over 90 years to solve the immense challenges inherent in the transition to sustainable energy sources. Therefore, whenever “2100” is mentioned with respect to projecting the U.S.’s and the world’s needed energy supplies, the reader should add the caveat “or perhaps much sooner” to maintain the correct perspective.

One way to appreciate the challenges ahead is in terms of harvesting energy where the planting-harvesting cycle for significant new sustainable energy sources is 20-30 years long (e.g., building 500 new nuclear power plants). The United States and the world may only have three energy harvest cycles—perhaps fewer—to make the successful transition to sustainable energy. Time is precious and is not to be wasted.

Executive Summary

Key findings:

1. By 2100, the number of people actually using electricity and modern fuels will more than double. Of the world’s current 6.6 billion people, 2.4 billion do not have access to modern fuels and 1.6 billion do not have access to electricity. As a result, a substantial percentage of the world’s population lives in a state of energy deprivation that substantially impacts health, individual economic opportunity, social and political stability, and world security. By 2100, the world’s population is projected to climb another 3.4 billion to roughly 10 billion. This means that by 2100, an additional 5-6 billion people, not using modern fuels and electricity today, must be provided with assured, affordable, and sufficient energy supplies if the world’s current energy insecurity is to be substantially eliminated.

2. By 2100, to meet reasonable energy needs, the total world’s energy production of electricity and modern fuels must increase by a factor of about 3.4X while that of the United States must increase by a factor of 1.6X. The annual per capita total energy consumption of Japan, South Korea, and Europe averages about 30 barrels of oil equivalent or BOE. Further energy conservation may reduce this to about 27 BOE per year. This value is used in this paper as a level of energy consumption needed for a modern standard of living and a stable political and economic environment outside the United States. By 2100, should the non-U.S. world population achieve this modern “middle class” standard of living, the world will require an annual energy supply of around 280 billion BOE. Today, the world’s electricity and modern fuels energy supply is about 81 billion BOE. Hence, by 2100, the world will need on the order of 3.4X more energy than is being produced today. In the United States, a near doubling of the population by 2100, even with a 20% reduction in per capita energy use, will require a 1.6X increase in U.S. energy needs.

3. If oil, coal, and natural gas remain the predominant source of energy, both known and expected newly discovered reserves will be exhausted by 2100, if not far earlier. Of the 81 billion BOE produced each year from all energy sources, 86% or 70 billion BOE comes from non-renewable oil, coal, and natural gas. At this percentage, by 2100, the world would need about 240 billion BOE from oil, coal, and natural gas. With an annual average of about 155 billion BOE through the end of the century, the world would need about 14,100 billion BOE of oil, coal, and natural gas to reach the end of the century. Current proved recoverable reserves of oil, coal, and natural gas totals only about 6,000 billion BOE. Expert estimates of additional recoverable reserves optimistically adds another 6,000 billion BOE—for example, including nearly 3,000 billion BOE from all oil from oil shale—for a combined total of around 12,000 billion BOE. [1] With increasing world energy consumption and if oil, coal, and natural gas continue to provide most of the world’s energy, known and new reserves of oil, coal, and natural gas will be exhausted by the end of the century, if not much earlier.

4. To transform the world to primarily sustainable energy by 2100 to replace oil, coal, and natural gas, current sustainable energy sources must be scaled up from today by a factor of 26. By the end of the century—perhaps decades earlier—the world will need to obtain almost all of its energy from sustainable energy sources: nuclear and renewables. Today, the equivalent of about 11 billion BOE comes from sustainable energy sources. By 2100, the world must increase the production capacity of sustainable energy sources by a factor of about 26 to provide the equivalent of 280 billion BOE. The two primary sources of sustainable energy today are nuclear and hydroelectric. Today, the world has the sustainable energy equivalent of about 350 1-GWe (gigawatt-electric) nuclear power plants and 375 2-GWe Hoover Dams. To meet the world’s 2100 need for 280 billion BOE of energy production, every four years through the end of the century, the world must add this amount of sustainable energy production in the form of nuclear, hydroelectric, geothermal, wind, solar, and biomass.

[Larger copy of the above chart]

5. Terrestrial sources of sustainable dispatchable electrical power generation will fall significantly short of U.S. and world needs by 2100 and, even, current U.S. needs. Energy is supplied in two primary forms: dispatchable electrical power to meet consumer needs for electricity and modern fuels to power transportation and other systems operating off the electrical power grid. By 2100, the world will need about 18,000 GWe of dispatchable electrical power generation capacity, compared with about 4,000 GWe today, with almost all generated by sustainable sources. [2] To assess the potential of nuclear fission and terrestrial renewables for meeting this world need, the addition of 1,400 1-GWe conventional nuclear fission reactors [3], the construction of the equivalent of 1,400 2-GWe Hoover Dams for added hydroelectric power generation, the addition of 1,900 GWe of geothermal electric power generation, and the expansion of wind-generated electrical power to 11 million commercial wind turbines, covering 1.74 million sq. mi., would only be able to supply about 47% of the world’s 2100 need for dispatchable electrical power generation capacity. [4] For the United States, only about 30% of the needed 2100 dispatchable electrical power generation capacity could be provided by these sustainable sources. By 2100, the U.S. and the world would be left with a dispatchable electrical power generation shortfall of 70% and 53%, respectively, with respect to this paper’s projection of the 2100 needs. Further, for the United States, the projected 2100 sustainable generation capacity would only provide about one-half of the current installed generation capacity that relies substantially on non-renewable coal and natural gas.

[Larger copy of the above chart]

6. Expanded conventional renewable sources of sustainable fuels—hydrogen, alcohol, bio-methane, and bio-solids—will not be able to meet the U.S.’s or the world’s 2100 needs for sustainable fuels. To assess the potential for conventional renewable sources of sustainable fuel for the entire world in 2100, hydrogen production from the electricity generated by nearly 600,000 sq. mi. of ground solar photovoltaic systems, hydrogen production from over 80% of the electrical power generated by 11 million wind turbines, and biofuels produced from 13,000 million tons of land biomass from the world’s croplands and accessible forestlands would only be able to supply about 37% of the world’s 2100 need for sustainable fuels. For the United States, by 2100, the situation is about the same with only about 39% of the 2100 needed fuels production capable of being provided from these conventional sustainable energy sources. As with sustainable electrical power generation, conventional sustainable U.S. fuels production at projected 2100 levels would fall well short of meeting current U.S. needs for fuel.

[Larger copy of the above chart]

7. Closing the U.S.’s and the world’s significant shortfalls in dispatchable electrical power will require substantial additional generation capacity that can only be addressed through the use of space solar power. Because of the substantial shortfall in needed 2100 fuels production, producing even more sustainable fuels to burn as a replacement for oil, coal, and natural gas to generate the needed additional electrical power is not practical. As a result, additional baseload electrical power generation capacity must be developed. The remaining potential sources of dispatchable electrical power generation are advanced nuclear energy and space solar power. While advanced nuclear energy certainly holds the promise to help fill this gap, fulfilling its promise has significant challenges to first overcome. Demonstrated safety; waste disposal; nuclear proliferation; fuel availability; and, for fusion and some fission approaches, required further technology development limit the ability to project significant growth in advanced nuclear electrical power generation. Space solar power (SSP)—involving the use of extremely large space platforms (20,000 or more tons each) in geostationary orbit (GEO) to convert sunlight into electrical power and transmit this power to large ground receivers—provides the remaining large-scale baseload alternative. Relying on SSP would require 1,854 5-GWe SSP systems to eliminate the world’s shortfall in needed 2100 dispatchable electrical power generation capacity. Of these, 244 SSP systems would be used to eliminate the U.S. shortfall in needed 2100 dispatchable electrical power generation capacity. The following two charts summarize this paper’s projection of the potential contribution of SSP in meeting the U.S.’s and the world’s dispatchable electrical power generation needs in 2100.

[Larger copy of the above chart]

8. In addition to eliminating the dispatchable electrical power generation shortfall, SSP could, with algae biodiesel, eliminate the sustainable fuels production shortfall. Excess SSP electrical power can be used, when demand is less than the SSP generation capacity, to electrolyze water to produce hydrogen. Closed-environment algae biodiesel production, done on the land under each SSP receiving antenna, combined with SSP hydrogen production can provide 24% and 19% of the United States’ and the world’s 2100 needed fuels production, respectively. The remaining fuels gap would be closed by warm-climate, open-pond algae biodiesel production. These two forms of sustainable fuels production—SSP hydrogen and algae biodiesel—would provide slightly more that 60% of this paper’s projection of the U.S.’s and the world’s 2100 needs for sustainable fuel production, as seen in the two charts below.

[Larger copy of the above chart]

9. Recognizing that the dedicated land area required in the United States to install the needed renewable energy production systems will be substantial, SSP provides one of the highest efficiencies in terms of renewable energy production capacity per sq. mi. of all the renewable alternatives. In the United States, 375,000 sq. mi.—about 12% of the continental United States—would be directly placed into use for renewable energy generation to meet this paper’s projection of 2100 energy needs. (For comparison, the U.S. arable and permanent cropland totals 680,000 sq. mi.) This land would be 100% covered with wind farms, ground solar photovoltaic systems, SSP receiving antennas, and open-pond algae biodiesel ponds. Of these four renewable energy options, SSP is one of the most land use efficient. The 244 SSP receiving antennas would require only about 20,000 sq. mi. or about 0.6% of the continental U.S., while providing nearly 70% of the dispatchable electrical power generation capacity and about 24% of the sustainable fuels production capacity by 2100.

Key conclusions:

1. Based on this assessment’s findings, a sound U.S. energy policy and implementation strategy should emphasize:

Finding and producing more oil, coal, and natural gas to meet growing demand in order to minimize energy scarcity and price escalation during the generations-long transition to sustainable energy supplies;

Adopting prudent energy conservation improvements to reduce the per capita energy needs of the United States, as well as the rest of the world, without involuntarily reducing the standard of living;

Aggressively transitioning to conventional nuclear and terrestrial renewable energy sources to supplement and then replace oil, coal, and natural gas resources to avoid dramatic reductions in available per capita energy as non-renewable energy sources are exhausted this century; and,

Aggressively developing advanced nuclear energy, space solar power energy, and open-pond/closed-environment algae biodiesel production to fill the substantial projected shortfalls in sustainable electrical power generation and fuels production that will develop even with optimistic levels of conventional nuclear and terrestrial renewable energy use.

2. While it is certainly easy to be disillusioned by these findings, this need not and should not be the case, especially in the United States. The world and the United States have successfully undergone a comparable transition in energy sources when wood was no longer sufficient to meet the growing needs of a rapidly industrializing world. When the transition to coal started in earnest in the 17th century, steam power, electrical power, internal combustion, and nuclear energy where yet-to-be-invented new forms of energy conversion that now power the world. For about four centuries, technological development, economic investment, and industrial expansion— undertaken to realize the potential of “easy energy”—have been a foundation of the world’s growing standard of living and the emergence of the United States as a great power. Now, recognizing that the end of easy energy is at hand, the United States needs to aggressively move to expand existing sources of sustainable energy and develop and implement new sources to foster continued technological development, economic investment, and industrial expansion in the United States during the remainder of this century. It is critical that the United States take a leadership position in the development of space solar power as this may become the dominant electrical power generation capability for the world.

Endnotes

1. Methane hydrates are not included in this estimate for reasons discussed in the paper.

2. Stable electrical power grid operations require sufficient dispatchable power generation capacity to meet, at any time, peak consumer demand plus a modest reserve margin. Only generation systems that have a high assurance of being available to deliver power on demand (e.g., nuclear, hydroelectric, geothermal, and carbon-fired generators) are considered dispatchable.

3. The addition of 1,400 conventional nuclear fission reactors is consistent with projections of available land resources of uranium fuel, without using breeder reactors, lasting upwards of 150 years. The significant use of uranium extracted from seawater is not assumed.

4. As discussed later in this paper, the variability of wind-generated electrical power is assumed to severely limit its ability to provide dispatchable electrical power. Most wind-generated electrical power is assumed to be used to produce hydrogen fuel.

===== End of excerpt =====

Copyright © 2008 James Michael Snead. Reproduction of the preceding excerpt (and the figures above) from the paper “The End of Easy Energy and What to Do About It” is permitted for personal, educational, and internal organizational use without prior written approval of J. M. Snead. Commercial printed and internet use (e.g., blog), including posting, and personal internet use (e.g., blog) and posting of only the preceding excerpted portion of the paper (and the figures above) for purposes of discussion are permitted provided full attribution and reference to this blog site is clearly made. For permitted and non-permitted reproduction or posting of the full paper, see the copyright notice on the paper. Notice: The author makes no warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information contained in this paper.

24 - Space solar power and America's energy future (Part 5)

2008-05-20T17:48:00Z

The Space-Based Solar Power study undertaken with the sponsorship of the U.S. Department of Defense's National Security Space Office has continued to elicit significant interest. As noted in Part 1 of this series, the fundamental premise of this study was that the United States should lead the world in making use of space solar power as a primary means for achieving an energy-assured future based on renewable energy sources.

Needless to say, the validity of the study's premise is not yet established. Significant technical, economic, and logistical issues related to beaming energy from space to the Earth still need to be addressed. Yet, the attractiveness of renewable, high-quality electrical energy delivered from space to terrestrial electrical power grids remains high.

Is strictly an economic comparison of space solar power vs. terrestrial alternatives still valid?

Some argue that while the needed technologies for building and operating space solar power systems may be resolvable, such space systems are unlikely to ever be economically competitive with terrestrial renewable and non-renewable alternatives. This argument, of course, presumes that terrestrial renewable and non-renewable energy sources will be sufficient in capacity and acceptable in terms of environmental impact to meet the world's energy needs. If this presumption is true, then the economics of space solar power vs. terrestrial alternatives likely will become the basis of a go/no-go decision. Looking at the flip side of this argument, however, a different decision criterion emerges.

In Part 1 and Part 2 of this series, I developed the following list of the most important to least important desirable energy outcomes as part of a discussion of developing a rational U.S. energy policy.

Energy sufficiency and energy availability
Energy assuredness and energy affordability
Energy acceptability
Energy economic opportunity

If terrestrial renewable and non-renewable energy sources are sufficient to meet future energy needs, then energy policy can turn from ensuring "energy sufficiency and energy availability" to ensuring domestic "energy assuredness and energy affordability." (See Part 1 for definitions.) However, if future needs cannot be met by terrestrial sources, then energy policy must remain focused on resolving this shortage. In this case, space solar power becomes a necessity. Comparative economic costs of space solar power vs. terrestrial energy sources, under these circumstances, are primarily useful in balancing investment in space solar power vs. terrestrial sources and for preparing the world's economy to provide the needed economic resources.

Whether building space solar power systems is an economic decision or an essential need hinges on whether terrestrial energy sources can meet the world's future needs. Currently, non-renewable hydrocarbon (NRH) fuels provide most of the world's energy—about 85%. Despite escalating NRH prices and apparent production limits, many still believe that these current primary world energy resources are sufficient to sustain world needs beyond any required planning horizon. Discussions of a post-NRH world are dismissed as being irrelevant based on the assumption that new discoveries and/or recovery technology improvements will prevent these resources from being exhausted within any time period of concern. Advocacy of space solar power, therefore, must start with assessing the future of NRH supplies.

What are the known and projected world reserves of non-renewable hydrocarbon energy supplies of oil, coal, and natural gas?

Table 1: World Non-renewable Hydrocarbon Proved Recoverable Reserves

[Larger copy of the above chart]

Table 2: World Non-renewable Hydrocarbon All Recoverable Reserves

[Larger copy of the above chart]

These two tables reproduce information contained in the World Energy Council's 2007 Survey of Energy Resources. The following notes explain how these tables were complied.

1. Proved recoverable reserves are what experts believe "can be recovered in the future under present and expected local economic conditions with existing available technology." Table 1 shows these values for conventional oil, coal, and natural gas.

2. The reserves for the two forms of unconventional oil (natural bitumen and extra-heavy oil), included in Table 1, are not proved reserves. Rather, as discussed in the cited reference, these "reserves or probably reserves, generally with no further distinction, are quantities that are anticipated to be technically (but not necessarily commercially) recoverable from known accumulations.” As with most NRH fuels, the expected recoverable reserves of these two sources of oil are only a modest percentage of the known accumulations which, in some sources, is placed in the trillions of barrels for these two sources. (See the note below regarding oil shale in Table 2.)

3. Table 2 lists the additional recoverable reserves generally defined as the "resource additional to the proved amount in place that is of foreseeable economic interest. Speculative amounts are not included." With the inclusion of these additional reserves, the total shown in Table 2 is an estimate of the total remaining NRH reserves that are recoverable at production levels needed to meet world needs. In this simple depletion model, when these reserves are exhausted, other energy sources will be needed.

4. Recovery of oil from oil shale is comparable to the recovery of the bitumen in that both are either mined or extracted using in situ heating to liquefy trapped hydrocarbons. The cited reference states: "Total world resources of shale oil are conservatively estimated at 2.8 trillion barrels." However, unlike, natural bitumen or extra-heavy oil, the cited reference does not include estimates of useful reserves. The total 2.8 trillion barrels of oil from oil shale is included in Table 2, not to reflect the actual expected proved recoverable reserves, but to provide a massive additional source of NRH fuels that can be used to assess what impact this may have on world energy consumption. Essentially, the inclusion of the full amount of the oil shale covers uncertainties in the additional recoverable reserves of natural bitumen, extra-heavy oil, oil from oil shale, as well as increased production resulting from improved recovery methods for conventional oil, coal, and natural gas.

5. In their 1983 book, The Future of Oil, Odell and Rosing reach the conclusion that 5 trillion barrels is the likely amount of recoverable conventional and unconventional oil. The conventional and unconventional oil reserves, including oil shale, in the two tables total about 5 trillion barrels providing one indication that the total for oil used in this simple analysis is of the right magnitude.

What are the units of energy used?

A Q-BTU is a quadrillion (one billion million) British Thermal Units (BTU). It is used as the standard unit of measure by the U.S. government for comparing various energy sources. (See Part 4 for additional information on this topic.) The M-BTU, used later, is one million BTUs. It is a measure of per capita energy consumption. There are one billion M-BTUs in a Q-BTU. The advantage of using these two units is that they enable extremely large magnitudes of national and personal energy consumption to be described with numeric values that are easily comprehended.

Why are all of the NRH reserves combined into one total?

As a heat source and as a raw material for the chemicals industry, modern technology has made oil, coal, and natural gas interchangeable. Coal can be transformed into either a gas product to replace natural gas or a transportation fuel to replace oil. One major oil company is touting the conversion of natural gas into a liquid transportation fuel. As the reserves of oil are depleted, with a corresponding increase in price of the remaining oil, natural gas and coal production will likely increase to replace the dwindling supply. For the simple reserve depletion model used in this analysis, combining all reserves in one total and comparing this against the world's total demand for NRH fuels was appropriate.

What will be the world's demand for NRH fuels throughout the rest of the century?

Figure 1: U.S. and Non-U.S. Population Model Used

[Larger copy of the above chart]

The starting point for projecting the world's demand for NRH fuels is to model the world's population growth through the end of this century. Figure 1 shows both the U.S. and non-U.S. world population based on U.S. Census Bureau data to 2050 extrapolated to 2100. (Note: The Census Bureau projections through 2050 show a declining birth rate compared to the death rate. In the simple population model used, births equal deaths about 2080 for the non-U.S. population. In the U.S. however, the U.S. population is still growing because of the larger families and second and third generation births of the large influx of aliens in the last decade and the coming decades.)

Figure 2: U.S. and Non-U.S. Per Capita Energy Needs (M-BTU)

[Larger copy of the above chart]

The U.S. data is based on U.S. Energy Information Administration (EIA) data for 2004 and projected 2030 national energy consumption. Using the Figure 1 population model for the U.S., the per capita energy needs were computed for 2004 and 2030. These two data points then were used to extrapolate usage to 2100 using the same rate of change as projected from 2004 to 2030. (Note: A decline in per capita U.S. energy consumption through 2030 is projected by the EIA. This rate of decline was extended to 2100 where per capita consumption would be about 91% of current usage.)

The non-U.S. per capita energy consumption was based on international energy consumption data also reported by the U.S. EIA. The total world consumption was reduced by the U.S. consumption. The resulting value was divided by the non-U.S. population to arrive at an estimate of the non-U.S. per capita energy needs. As with the U.S. per capita energy needs, the trends from 2004 to 2030 were extrapolated to 2100.

In this model of non-U.S. per capita energy usage, by 2100 the non-U.S. per capita energy needs would be approximately 50% of the U.S. per capita energy needs. Currently, Japan and Western Europe per capita energy consumption is about 50% of that of the U.S. Hence, reaching a 50% value in 2100 represents a target where the per capita energy consumption and standard of living, outside of the U.S., would be comparable to that of Japan and Western Europe. The transformation of the world to a western standard of living would then be essentially complete.

Figure 3: Annual Future Energy Needs (Q-BTU)

[Larger copy of the above chart]

The U.S. and non-U.S. world per capita energy needs can be applied to the U.S. and non-U.S. populations to project the annual future U.S. and non-U.S. energy needs. Summing these two values yields the world's total annual future energy need. This is shown in Figure 3, above. By 2100, the U.S. percentage of world energy use would fall from about 25% today to about 10%. (Note: If the rapid industrialization of China and India continues, the annual non-U.S. energy demand would be expected to increase more rapidly in the coming decades than shown in the above figure.)

In 2005, the world used about 455 Q-BTU. By 2100, this need will grow to about 1,500 Q-BTU, based on population growth and standard of living improvement. Hence, in 2100, the world will require about 3.4 X of the 2005 level of energy production.

Figure 4: World Total and Non-renewable Hydrocarbon Energy Needs (Q-BTU)

[Larger copy of the above chart]

From U.S. EIA and similar projections of future world energy use, the world is "still" expected to meet about 85% of its energy needs through 2030 with NRH fuels. Figure 4 extends this percentage through 2100 to predict that, should NRH fuels still be readily available and affordable, about 1,300 Q-BTU of NRH fuels will be needed. This is about 3.4X the NRH fuels consumed in 2005.

Figure 5: World Cumulative NRH Future Energy Needs vs. Reserves (Q-BTU)

[Larger copy of the above chart]

Using the annual world NRH fuels needs, shown in Figure 4, a simple resource utilization analysis can provide a ballpark estimate of when the NRH fuels may be exhausted. In Figure 5, the cumulative world need for NRH fuels is plotted. The projected NRH fuel reserves are then drawn down by this cumulative world need until the reserves are exhausted.

As seen in Figure 5, the current proved recoverable NRH reserves will be exhausted about 2060. This leaves an end-of-century NRH deficit of about 45,000 Q-BTU, which is equivalent to over 100 years of current NRH consumption.

For the "best case" using all proved and additional recoverable reserves—including the 3 trillion barrels of oil from oil shale—these reserves will be exhausted about 2084; slightly more than one generation after the first case. The end-of-century NRH deficit would be about 20,500 Q-BTU, which is equivalent to about 50 years of current NRH consumption.

What improved understanding does this model provide?

1. Growth in world per capita energy needs, spurred by expectations of an improving standard of living as a sign of political and economic success, will dramatically increase needed energy supplies throughout this century.

2. An energy planning horizon of 20-30 years, when non-renewable hydrocarbon fuels provide the vast majority of the world's energy, does not adequately anticipate nor respond to the world's energy situation this century.

3. By the end of the century, the world will need to fully replace nearly all production of non-renewable hydrocarbons with renewable or nuclear alternatives with a total world energy production capacity of 3-4 times that of today.

4. Undertaking a transformation from primarily non-renewable to primarily renewable/nuclear energy production is a necessity, if this model's projections of NRH reserves are reasonably accurate.

5. The stage is now set to compare space solar power against terrestrial renewable and nuclear energy sources, not in terms of economics, but in terms of the magnitude of the energy needed to meet world needs.

Closing caveat:

This simple model did not look at the potential to make use of the frozen methane hydrates that are discussed as a future non-renewable hydrocarbon supply. Neither the technology needed to exploit these reserves on an industrial scale nor the environmental issues associated with such energy production are sufficiently understood to incorporate this into energy planning.

23 - AstroPolitics essay - "Spacefaring Logistics Infrastructure: The Foundation of a Spacefaring America" by Mike Snead

2008-04-01T15:40:00Z

AstroPolitics: The International Journal of Space Politics and Policy (Vol 6, No. 1; Janurary-April 2008) recently published my essay "Spacefaring Logistics. The entire paper can be downloaded, for personal use, from the spacefaring resources page on http://mikesnead.net.

Introduction

Surprisingly, almost two generations after Apollo 11, neither America nor any other country is yet a true spacefaring nation. None possess the spacefaring capabilities needed for humans to routinely and safely access space and operate in space. This status stands in sharp contrast to the general recognition that, as highlighted in the United States National Space Policy, America will significantly benefit from becoming a true spacefaring nation with full freedom of action in space. What’s missing is the spacefaring logistics infrastructure that forms the core of America’s spacefaring dream. This dream of Americans, as spacefarers, being able to safely and routinely access and work in space remains the benchmark for assessing American progress in space.

This paper focuses on how this American spacefaring dream can now start to be realized. Specifically, this paper focuses on how America can undertake the transformation from an aging space exploring nation to a vibrant spacefaring nation by, first, focusing America’s aerospace industries on building and operating an integrated spacefaring logistics infrastructure and, then, using the newly acquired mastery of human space operations to enable the emergence of a new generation of commercial space enterprises. This combination of new spacefaring infrastructure, new industrial mastery of spacefaring operations, and new commercial space enterprises will take America into a new era of the space age where America is truly spacefaring.

Table of Contents

Introduction
Birth and decline of the American spacefaring dream
The renewed importance of America becoming spacefaring
Logistics infrastructure's role in establishing mastery of operations in new frontiers
Crossing the threshold to true spacefaring operations
Spacefaring logistics infrastructure implementation objectives
Conclusion

Mike Snead

22 - Assessing the Practicality of Scramjet-Powered, Single-Stage Aerospaceplanes

2008-03-31T18:12:00Z

The following is an essay published in The Space Review on March 31, 2008. This essay responds to a earlier Space Review essay by Eric Hedman.

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Assessing the Practicality of Scramjet-Powered, Single-Stage Aerospaceplanes

By Mike Snead

Clearly, the United States needs improved space access with “aircraft-like” safety and operability. In his Space Review article, “Space launch evolution and revolution” (The Space Review, December 10, 2007), Eric Hedman advocates focusing American space access development efforts on scramjet-powered, fully-reusable aerospaceplanes. He states: “The Holy Grail of low per passenger cost launcher concepts keeps coming back to scramjets.”

Scramjet-powered space access was first investigated, in the United States, in the late 1950’s and early 1960’s as part of the Department of Defense’s first aerospaceplane studies. These studies started what has now been nearly a half century of research into the design and performance modeling of scramjet engines and scramjet-powered flight systems.

From a top-level system design and operability perspective, a single-stage aerospaceplane is certainly, as Hedman highlights, the Holy Grail. As the United States struggles in its transformation into a true spacefaring nation, there is a critical need to identify a practical strategy to meet the need for aircraft-like, fully-reusable space access. Should scramjet-powered aerospaceplanes be placed front and center in the pursuit of the needed improved space access capabilities or is another approach the more practical approach at this time? As with any quest, success lies with selecting the more readily implementable path. This article summarizes some of the challenges involved in the scramjet-powered aerospaceplane path.

Scramjet fundamentals

All airbreathing jet engines have four primary segments – inlet, compressor, combustor, and nozzle. What is unique about the scramjet is that the airflow velocity through the combustor is designed to exceed the local speed of sound. “Scramjet” is an abbreviation for “supersonic combustion ramjet.”

In turbojets and ramjets, the velocity in the combustor is kept below the local speed of sound to enable efficient fuel injection, mixing, and combustion. As the flight velocity increases, useful energy in the incoming air is lost—converted to excessive heat that must be actively cooled—as the air flow is decelerated in the inlet and compressor to local subsonic speeds for entry into the combustor. This subsonic combustor speed limit effectively places an upper bound on aircraft’s flight velocities of around Mach 3-5 for pure turbojets and around Mach 6-7 for pure ramjets.

The scramjet reduces this loss by intentionally keeping the local flow speeds through the engine supersonic. If the scramjet engine and vehicle can be designed to withstand the flight external and internal temperatures and pressures, and if fuel combustion can be maintained, then very high airbreathing flights speeds, perhaps as high as Mach 15, may be achievable.

Research efforts to advance basic scramjet propulsion technologies, first begun in the 1960’s, continue. In 2004, for example, the 1,400 kg, 4.7 m-long, scramjet-powered, X-43A achieved an airbreathing speed of Mach 9.6 for about 10 seconds. A large rocket was used to boost the X-43A, following its release from the B-52 carrier aircraft, to the hypersonic test conditions needed to perform the scramjet engine’s tests.

Space access design considerations

For typical space launch systems using liquid-fueled rocket engines, both the fuel and oxidizer must be carried internally. The Space Shuttle does this with its large External Tank. Through the addition of airbreathing propulsion, some of the oxidizer is instead provided by the atmosphere. Ideally, the use of airbreathing as well as rocket propulsion enables the mass of the oxidizer and oxidizer tanks to be reduced. This approach, it is anticipated, will yield an aerospaceplane design that has a reduced takeoff gross weight when compared with the pure rocket baseline design.

The apparent advantage of using scramjets for aerospaceplanes is that the maximum flight velocity, where air still provides the needed oxidizer, can be high. Theoretically, a significant reduction in the propellant mass fraction can be achieved. The airbreathing “Holy Grail” Hedman notes is that such a reduction may enable a “closed design” for a single-stage aerospaceplane to be achieved. As described in the following, this path has many challenges that have yet to be successfully addressed. It is worth noting that closed designs of pure rocket-powered, single-stage aerospaceplanes, capable of achieving aircraft-like safety and operability using current technologies, have also not been proposed.

Single-stage space access system mass fractions

To better understand the design challenges of achieving a closed single-stage aerospaceplane design, an understanding of the concept of mass fractions is needed.

A single-stage aerospaceplane’s takeoff mass can be divided into two categories—propellant mass fraction and empty mass fraction—usually expressed as a percentage of the takeoff mass. The sum of the two fractions, by definition, is 100 percent. As one increases, the other must decrease.

As the name implies, the propellant mass fraction is the percentage of the aerospaceplane’s takeoff mass that is propellant—fuel and oxidizer. The propellant mass fraction required to achieve orbit is mathematically calculated from the change in velocity needed to achieve orbit, the losses due to drag and trajectory that must be accounted for, and the propulsion subsystem’s net efficiency in converting the fuel’s energy into increasing vehicle velocity.

The net propulsion efficiency is the net thrust produced per unit mass of propellant consumed. This is the familiar “specific impulse” term that is used, along with the thrust, to describe the performance of a rocket engine. It can also be used for airbreathing engines. By using oxygen from the air, instead of from onboard tanks, airbreathing engines ideally increase the net propulsion efficiency by decreasing the mass of propellant consumed each second to yield the same thrust. This has the benefit of reducing the theoretical propellant mass fraction.

For a rocket-powered, single-stage aerospaceplane, the theoretical propellant fraction to achieve orbit will range from about 88-95 percent. This means that 88-95 kg of every 100 kg of takeoff mass must be propellant if orbit is to be achieved. Rocket-powered aerospaceplanes are essentially large flying propellant tanks.

Ideally, when a very efficient airbreathing-rocket engine combination is used, the theoretical propellant fraction reduces to about 60-70 percent. As a result, the empty mass fraction for the scramjet solution (30-40 percent) can be two to eight times larger than that for a pure rocket design (5-12 percent). From a design perspective, this provides a substantial apparent advantage to the airbreathing approach. It seems obvious that an airbreathing design where 30-40 kg of every 100 kg of takeoff mass can be hardware would be easier to design and build compared with a pure rocket design that only permits 5-12 kg of every 100 kg of takeoff mass to be hardware.

By subtracting the theoretical propellant fraction from 100 percent, the remaining fraction is the empty mass fraction objective—what the design engineers need to achieve. If a safe, operable, and buildable design can be defined where the predicted empty mass fraction is equal to or less than this objective, the design is said to “close.”

Challenges in closing the design of single-stage, scramjet-powered systems

Today, the American aerospace industry has the ability to design and build two-stage, fully-reusable space access systems that are believed to “close” based on the results of government and industry conceptual design studies using current technologies. Generally, these designs use a vertical takeoff, horizontal landing approach that is pure rocket powered. The original fully-reusable design for the Space Shuttle from the early 1970’s, before the design was changed to the expendable External Tank and Solid Rocket Boosters, is an example of this configuration.

While various ideas for single-stage, scramjet-powered aerospaceplanes have been proposed since the 1960’s, closed single-stage designs using current technologies and capable of aircraft-like safety and operability have not yet been achieved. Why is this? The problem is that the use of scramjets adds significant complexity to the design and verification of a single-stage aerospaceplane while at the same time adding uncertainty to the estimation of the required propellant fraction. Essentially, it makes the problem of predicting design closure and then demonstrating a successful design much harder, as discussed in the following examples.

- Added propellant tank mass

One design challenge is that scramjet airbreathing propulsion adds significant additional empty mass that is not needed for a pure-rocket system. While the addition of airbreathing propulsion may decrease the required propellant fraction, the average propellant density may also decrease. This can result in disproportionally larger total propellant tank volume and larger tank total mass.

This design dilemma results from the fact that a scramjet requires hydrogen as the fuel for flight speeds greater than about Mach 7. Hydrogen, it is hoped, will have the ability to sustain combustion in the scramjet’s supersonic combustor at these higher Mach numbers where no other fuel appears to be able to sustain combustion unaided. Liquid hydrogen, however, has the disadvantage of having a very low density—a beverage cup that holds 16 oz. of water only holds about 1 oz. of liquid hydrogen. Liquid hydrogen also is very cold with a temperature close to absolute zero. This requires added tank insulation and special fuel tank pressurization management. Increased tank volume, increased tank insulation, and special fuel tank pressurization management generally yields increased tank mass per kg of propellant carried.

- Added thermal protection subsystem mass

Closely related to the likely increase in total propellant tank mass is the additional thermal protection subsystem (TPS) mass required for hypersonic scramjet operations. All reusable space access systems require thermal protection during reentry. During ascent under rocket power, the thermal loads are comparatively moderate and no additional thermal protection is normally required. The thermal protection required during scramjet-powered ascent can, however, exceed that required for reentry. As a result, the total TPS mass will usually increase, compared with a pure-rocket design, due to the higher temperatures, higher aerothermal loads, the increased need for active cooling, and the larger total propellant tank surface area.

- Added propulsion subsystem mass

Another empty mass design issue is the increase in the mass fraction of the propulsion system to incorporate airbreathing propulsion. In oxygen-kerosene rocket engines, for example, the installed engine thrust-to-weight ratio is about 60-80 while it is about 50-60 for oxygen-hydrogen rocket engines. The installed thrust-to-weight of the best supersonic turbofans is about 5-8 and about 8-12 for the best subsonic turbofans. The complexity of the design of the scramjet, combined with the need to retain a rocket engine capability, means that the installed thrust-to-weight of the integrated airbreathing-rocket propulsion subsystem for an aerospaceplane may only be in the range of 3-5. Compared with a pure-rocket design where the engines may comprise about 2-3 percent of the takeoff mass, the integrated airbreathing-rocket engine may 10X heavier, comprising 20 percent or more of the takeoff mass, or about half of the allowable empty mass fraction.

- Uncertainty in predicting the required propellant fraction

Design challenges also arise on the propellant fraction side of the design closure ledger. To develop a thorough closed design, good confidence in the accuracy of the required propellant fraction is needed—typically, 3-4 significant figures. This then enables the design engineers to confidently calculate the empty mass fraction objective and have a good definition of the specific flight conditions that need to be addressed—dynamic pressures, aerothermal loads, etc.

Unfortunately, modeling and verifying the performance of an integrated airbreathing propulsion subsystem from Mach 0-15 remains very challenging. Limited ground and flight scramjet test data means that there remains substantial uncertainty about the actual achievable performance, especially at high Mach numbers. While further scramjet technology development and testing may resolve this issue, substantial further improvement in scramjet performance modeling is required before the conceptual design closure of scramjet-powered aerospaceplanes can be achieved.

Scramjet testing design and verification challenges

Rocket and airbreathing engines are extensively tested to verify performance, safety, and operability. New jet engine designs routinely undergo thousands of hours of ground test while 500-1000 test firings of a new rocket engine design is the norm. For an airbreathing propulsion system that includes scramjets, the wide range of airbreathing operation from Mach 0 to 15 will require more extensive testing than is typically done for jet engines.

One challenge hindering scramjet development is that ground test facilities for full-scale testing of airbreathing propulsion systems are quite limited for Mach numbers greater than about Mach 3-4. Achieving the correct combinations of airflow velocity, mass flow rate, temperature, and sustained test conditions in test sections of the needed size for large scramjets is very difficult. Because of this, more extensive use of flight testing would be the presumed alternative approach. As the recent X-43A test program has shown, scramjet flight testing is very expensive and time consuming. The seven-year X-43A program, using three small expendable test vehicles, cost approximately $230 million. Two of the three tests conducted were successful in demonstrating scramjet operations for a total of about 30 seconds of test data. Relying on flight testing to very high Mach numbers, assuming this is successful, will add significantly to the length of time and cost required to successfully develop a scramjet for an aerospaceplane.

Scramjet-influenced airframe structural design and verification challenges

A key element of a successful airframe structural design is one that can be economically built and tested. Fabrication and test considerations are as important to the airframe’s design as are the aero-thermal-inertia loads. An innovative structural design engineer may be able to conceptualize a highly efficient, low-mass airframe design, but it may not be able to be successfully built and/or tested. This is especially important for aerospaceplanes because of the significant aerothermal loads acting on the vehicle during descent and, with scramjet propulsion, during ascent.

An example of the design and verification testing challenges that will arise with scramjet-powered aerospaceplanes comes from the National Aerospace Plane (NASP/X-30) program of the late 1980’s. It focused on a scramjet-powered, horizontal takeoff and landing, single-stage system that would have a takeoff mass of about a half-million kilograms—about the same as the new Airbus A380.

New airframe designs go through a series of component and full-scale ground tests to verify structural integrity. This is done for X- and Y-aircraft’s airframe design as well as for the production aircraft’s airframe design. Such testing involves the initial static tests to establish the strength and stiffness of the structure followed by cyclic testing to establish the damage tolerance and durability of the structure. The need for scramjet-powered systems to carry liquid hydrogen, combined with the time-dependent aero-thermal loads from the use of high-Mach airbreathing propulsion during ascent, adds significant complexity to the airframe’s structural testing.

While most airframe structural testing is conducted in ambient air environments, this will probably not be possible for scramjet-powered aerospaceplanes. Because no other liquid properly simulates the thermal response and mass characteristics of the liquid hydrogen in the fuel tank, structural testing of the airframe of scramjet-powered aerospaceplanes may be expected to require testing with, perhaps, several hundred tons of liquid hydrogen onboard. Any type of structural testing involving flammable liquids poses additional safety constraints. Testing of hydrogen is, perhaps, the most difficult because of hydrogen’s flammability in air at low concentrations and hydrogen’s ability to escape through small leaks when other gases cannot—such as small cracks in the tank walls or internal piping. The risk of even small structural failures that release hydrogen requires that such testing be done in special inerted facilities, possible the size of a domed football stadium, located several kilometers away from inhabited buildings.

High Mach airbreathing propulsion also introduces the variable of time in the structural verification testing because the internal airframe/tank temperatures and internal loads are time dependent. When combined with the changing external aero-thermal-inertia loads acting on the airframe as the vehicle accelerates to the Mach 15 scramjet cutoff velocity, this presents a very complex structural test matrix consisting of, potentially, hundreds of different test points covering both ascent, reentry, and emergency flight conditions.

Using past plans for NASP/X-30 structural testing as the example, the quantity of liquid hydrogen in the tanks would be set to the amount remaining at that point in the flight profile and the internal structure would be brought to the design internal temperature conditions using, probably, internal electrical heating elements. The external thermal and mechanical loads would then be applied over hundreds of square meters of surface area. At the same time, the airframe and scramjet’s active cooling system, using gaseous hydrogen at pressures up to 5,000 psi, would be started to simulate the cooling of much of this external surface area to ensure the correct airframe internal thermal loads and structural deformation. Obviously, such structural testing involving large quantities of combustible fluids near absolute zero, radiant thermal loads developing external TPS temperatures of over 1000 F, hot hydrogen gas at high pressures and temperatures flowing through hundreds of square meters of minimum-gage, actively cooled structures, and large mechanical loads that induce significant structural deflection, will be challenging to undertake.

Further complicating the structural integrity tests is that they will not be comprised of a single test for each design point. As mentioned, the initial static strength and stiffness verification of the structural integrity of the airframe may involve hundreds of test points to release the system for flight test and support envelope expansion. Some of these test points will probably need to be retested using actual flight-measured temperature and aero loads. Also, verification of the resistance of the airframe to loss of structural integrity brought about by temperature cycling and operational usage will involve further repetitive load testing of hundreds to thousands of cycles when the time comes to verify the structural integrity of the production configuration.

These structural design and testing challenges indicate that, as with scramjet engine testing, the structural development of scramjet-powered aerospaceplanes will be much more complex than that required for the more traditional airframe design expected to be used in two-stage, rocket-powered aerospaceplanes.

Scramjet-powered aerospaceplane program length and cost

The final challenge facing the development of scramjet-powered aerospaceplanes is the length and cost of their development programs. One estimate, prepared in 2003, stated that the projected cost through 2018 for “large-scale scramjets and turbojets,” as part of the National Hypersonics Initiative, was $8-14 billion. (Turbojets would be needed to accelerate the vehicle to the Mach 4-7 speed necessary for the ramjet/scramjet to start to operate.) The additional technology development demands for the airframe, thermal protection system, propellant tanks, and other flight-critical subsystems influenced by the use of hypersonic airbreathing propulsion will add significantly to the necessary technology risk reduction investments that would also be required.

A primary consideration in laying out a projected development timeline for a scramjet-powered aerospaceplane is the recognition that much of the needed technology development and maturation will involve substantial flight testing. The reality of scramjet propulsion is that test size counts due to the influence of the boundary layer characteristics on the engine operation. Hence, small test engine sizes, such as used on the X-43A, have inherent limits on their contribution to technology maturation. Near full-scale engines will be needed to verify engine performance and operability and near full-scale flight systems will be needed to demonstrate the ability to actually achieve orbit.

It may be expected that following the completion of the preliminary round of technology development efforts—perhaps by 2020 assuming sufficient funding—a near full-scale X-aircraft using all representative flight hardware designs, covering the full airbreathing range from Mach 0 to Mach 15, would be built. This would be followed by a pre-production Y-aircraft that is near full-scale and includes the rocket propulsion system to verify the ability to achieve orbit and reenter safely. Once the Y-aircraft program is successfully completed, the production program would start. With a typical design, build, test cycle of 10 years for advanced flight systems and starting in 2020, the X-aircraft program could be completed in 2030, the Y-aircraft program in 2040, and the production system could become operational about 2050.

Conclusion

With the impact of the upcoming termination of Space Shuttle operations on American space operations, it is very apparent that the United States needs substantially improved passenger and cargo space access. It is also clear that only a fully-reusable system design will enable improved “aircraft-like” safety and operability to be achieved. The alternative to the scramjet-powered, single-stage aerospaceplane approach is the two-stage, rocket-powered, fully-reusable aerospaceplane. The technologies required to start development of this approach are sufficiently mature that production development of the first generation could start now. By 2020, perhaps as early as 2016, such a two-stage aerospaceplane system could become operational and America’s ability to access space will leap forward more than three decades earlier than pursuing the scramjet-powered, single-stage approach.

Getting passengers and cargo to space with “aircraft-like” safety and operability are the primary needs of a true spacefaring nation. Hopefully, further technology development will yield single-stage capabilities in the future. While such technology development should continue, it is important that America’s future in space not be held hostage by the imposition of the scramjet technology path to space. Achieving aircraft-like safety and operability are the only design prerequisites and these will bring the desired lower costs. Starting the development of rocket-powered, two-stage, fully-reusable aerospaceplanes is, today, America’s readily implementable option to meet its space access needs as a true spacefaring nation.

21 - Space solar power and America's energy future (Part 4)

2008-02-27T00:06:00Z

Minor typo correction made 20080401

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The United States consumes about 100 Q-BTU of energy per year while the total world consumes about 450 Q-BTU. But what is a Q-BTU or quadrillion British Thermal Units? This blog addresses this question.

British Thermal Units

British thermal units or BTU is defined as the amount of heat (meaning energy) required to be added to one pound of water to increase its temperature by one degree Fahrenheit. In the United States, it has remained as a common unit for expressing the energy release associated with fuels.

A quadrillion BTU is 1,000,000,000,000,000 BTU. This is written in scientific notation as 1 x 10^15 BTU. In this series, this is abbreviated as Q-BTU, instead of the abbreviation "quad" used by some, just to make sure that it is understood that BTU is being discussed.

For these discussions of America's energy future, the Q-BTU is the unit used by the U.S. government to report and forecast energy consumption, as shown in Part 1 on this series (SA blog 15).

Work and power

To be useful, energy must be transformed through some mechanical means into work. Work performed in a period of time is power.

A human climbing stairs works to increase his or her potential energy. The amount of work performed is equal to person's weight times the height climbed. Climbing two flights of stairs requires twice the work of climbing the first flight. The body's muscles convert sugar (the energy source) into mechanical force that lifts the weight of the human.

The amount of power generated as the stairs are being climbed is the work performed divided by the time required. If the stairs are climbed twice as fast, then twice the power has been generated even though the total work performed was the same.

The U.S. consumes about 100 Q-BTU of energy, in all forms, per year. This is an expression of energy per unit of time, which is power. The common unit of power is the watt, named after James Watt.

One watt is defined as one joule of energy per second. To convert BTU per year into watts, as is done below, requires a conversion of BTU into the metric unit of energy - the joule. 1 BTU = 1055.056 joules. Hence, 1 BTU per second = 1055.056 joules per second or 1055.056 watts.

A person climbing stairs at a normal rate is expending about 200 watts of power or 200 joules per second.

When discussing electrical power, the common units in the U.S. are:

Kilowatt (kW) = 1,000 watts

Megawatt (MW) = 1,000,000 watts or 1,000 kW

Gigawatt (GW) = 1,000,000,000 watts or 1,000 MW or 1,000,000 kW

Quadrillion BTU to Gigawatt conversions

1 Q-BTU (energy) = 1 x 10^15 BTUs x (1055.056 joules per BTU) = 1055.056 x 10^15 joules (energy)

1 Q-BTU of electricity produced per year (power) = 1055.056 x 10^15 joules per year / (365 days per year x 24 hours per day x 60 minutes per hour x 60 sec per minute) = 33.5 x 10^9 joules/sec or watts (power) = 33.5 x 10^6 kilowatts (kW) = 33.5 X 10^3 Megawatts (MW) = 33.5 Gigawatt (GW) of continuous production

Sustained electrical power generation

Electrical power generation is a sustained operation. To define the amount of power being continuously generated, the watt-hour is defined as one watt of power produced for one hour. This concept is also applied to yield kW-hour, MW-hour, and GW-hour with the kW-hour (or kW-hr) being the common unit for commercial power generation.

1 Q-BTU of electricity per year = 33.5 x 10^6 kW per year x (365 days per year x 24 hours per day) = 293.5 x 10^9 kW-hrs = 293,500 GW-hrs

Electrical power costs

Quite often comparisons of alternative forms of electrical power generation are made in terms of the cost per kW-hr.

1 Q-BTU of electricity per year = 293.5 x 10^9 kW-hr x $0.01 per kW-hr = $2.9 billion @ $0.01 per kW-hr

1 Q-BTU of electricity per year = 293.5 x 10^9 kW-hr x $0.075 per kW-hr = $22 billion @ the avg. U.S. retail electricity price of $0.075 per kW-hr

Comparisons of oil, coal, natural gas, and nuclear

Using the Q-BTU as the basis for comparison, the cost of these four energy sources can be estimated.

1 Q-BTU (oil) = 1 x 10^15 BTU / 5.8 x 10^6 BTU per barrel of oil = 172 million barrels

1 Q-BTU (oil) = 172 x 10^6 barrels x $100 per barrel (spot market price 20080220) = $17.2 billion

1 Q-BTU (coal) = 1 x 10^15 BTU / 22.4 x 10^6 BTU per short ton of coal = 44.6 million tons

1 Q-BTU (coal to produce electricity) = 44.6 million tons x $34.3 per ton (avg. 2006 price for electric utilities) / 0.35 (avg. plant generation efficiency) = $4.4 billion

1 Q-BTU (natural gas) = 1 x 10^15 BTU / 1031 BTU per cubic ft = 970 x 10^9 cubic ft of natural gas

1 Q-BTU (natural gas to produce electricity) = 970 x 10^9 cubic ft / 1000 x $7 per 10^3 cubic ft / 0.35 (avg. plant generation efficiency) = $19.4 billion

1 Q-BTU (uranium in the form U3O8 used to power nuclear reactors) = 1 x 10^15 BTU / 50 x 10^9 BTU per short ton of U3O8 = 20,000 short tons of U3O8

1 Q-BTU (U3O8 to produce electricity) = 20,000 short tons U3O8 x 2000 lb per short ton x $75 per lb of U3O8 (spot market price 20080220) / 0.35 (avg. plant conversion efficiency) = $8.6 billion

20 - What to tell the next President about realizing America's potential in space

2008-02-04T15:54:00Z

The following is an essay published in The Space Review on February 4, 2008.

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The start of the new presidential administration in 2009 will be a critical time for America's non-military space efforts. The Vision for Space Exploration (VSE) has pronounced Bush administration fingerprints and may not have the public support needed to weather the upcoming political debate on its future. More importantly, as the presidential debate shifts from foreign affairs to the domestic economy, no presidential candidate has yet seized on the potential of America's industrial future in space as a key economic and technological catalyst for reestablishing America's competitiveness and world leadership, and substantially helping America to become energy independent. American political leaders apparently remain blind to the true potential of space in the coming decades of the 21st century and do not yet publicly recognize that a new race for space industrialization is starting among the world's technological nations.

The clear importance of space to America's future is summarized in the current U.S. National Space Policy: "In this new century, those who effectively utilize space will enjoy added prosperity and security and will hold a substantial advantage over those who do not. Freedom of action in space is as important to the United States as air power and sea power. In order to increase knowledge, discovery, economic prosperity, and to enhance the national security, the United States must have robust, effective, and efficient space capabilities."

The Eisenhower Center for Space and Defense Studies, associated with the United States Air Force Academy, conducts public forums to discuss issues of importance to America's future in space. This past fall, for example, they hosted a conference on Space-Based Solar Power (SBSP) at which the results of the informal SBSP study, sponsored by the National Security Space Office, were presented.

On 7-8 February 2008, the Center will hold this year's National Space Forum, "Space Challenges Facing the New American Administration of 2009." The focus of the opening panel, including Ambassador Roger Harrison, Director of the Eisenhower Center, and General C. Robert Kehler, Commander, U.S. Air Force Space Command, will address the "key decisions that will need to be made in regard to space policy when a new American Administration comes to power in 2009." The panel members will respond to questions about military, commercial, and civil space provided by the moderator and forum participants.

As this presidential campaign unfolds, it is up to the American pro-space industrialization community to proactively identify and communicate the importance of space to the candidates. Our responsibility is to provide the next president with a substantially improved understanding of the true potential of space industrialization and what new initiatives can and should be pursued. The upcoming National Space Forum is an excellent opportunity to advance this critical discussion. Given the opportunity, I would ask the opening panel participants these three questions:

1. Has a new strategic race for space started between the world's leading nations to gain the knowledge, discovery, economic prosperity, and national security advantages that true spacefaring nations will enjoy over non-spacefaring nations?

2. What specific steps, actions, policies, and new initiatives should the U.S. government and American aerospace industry undertake to enable America to effectively utilize space?

3. What changes in American spacefaring logistics infrastructure are needed to provide the U.S. government and commercial space industry with the robust, effective, and efficient space capabilities needed to access and operate in space safely, routinely, and profitably?

Certainly, there are many other space-related issues that also need to be addressed: ITAR, VSE, extended use of the Space Shuttle, space science, COTS, etc. However, the real strategic issue on the table for the next administration is about the needed transformation of America into a true spacefaring nation. We are not yet at this point and our current civil and commercial programs are not bringing us closer to this goal where Americans, as spacefarers, will be able to safely and routinely access and operate in space. To change course to enable America to successful compete and win the new space race, the next American president will need to set new strategic goals for civil and commercial space. The American pro-space industrialization community must take a leadership position to help to define the near-term options for substantially improving America’s ability to utilize space.

Mike Snead