Section III – How Long Will Fossil Fuels Continue to Sustain America’s Energy Needs?
Where will this 2.23 trillion BOE of energy come from? Almost everyone assumes the vast majority of this will be supplied by fossil fuels. As seen in Fig. 10, over the last 30 years, fossil fuels have provided about 85% of America’s energy needs. Is it reasonable to expect this level of supply to continue, especially as the total U.S. energy need substantially increases by 2100? If the answer is no, then the United States has a serious energy security problem. To find out, the U.S. fossil fuel endowment needs to be determined and compared against the 2.23 trillion BOE needed through 2100. The starting point is to understand the terminology.
A. Terminology is important in understanding the U.S. endowment of useable fossil fuel resources
Prior to the start of the current recession, nuclear and renewables provided about 15% of the annual gross thermal energy supply. Fossil fuels provided the balance of about 85%. Also, as seen in Fig. 10, for the last twenty years, even as wind and ground solar energy have been emphasized, the total contribution of renewables, as a percentage of per capita energy use, has stayed about the same percentage. Thus, a substantial continued reliance on fossil fuels would be expected into the foreseeable future. The United States simply has no other choice at this time.
As estimated earlier, from 2011-2100 the United States will need about 2.23 trillion BOE of gross thermal energy. If 85% of this is to be provided by fossil fuels, the United States will need about 2 trillion BOE of coal, oil, and natural gas through 2100. Does the United States have at least this amount of available domestic resources of these fuels—what the Congressional Research Service calls the “endowment”? The starting point for answering this question is to define some terms particular to non-sustainable natural resources like fossil fuels. These are illustrated in Fig. 11.
The Earth has immense stores of fossil fuels accumulated through some truly amazing geological processes over a period of several hundred million years. These range from coal, formed under tall mountain ranges, to methane hydrates stored in a unique form of water ice generally buried under the seafloor in the deep ocean.
Fossil fuels, of course, are solar energy stored as chemical energy in carbon molecules. In all fossil fuels, releasing the stored solar energy requires combustion with oxygen from the air, yielding carbon dioxide as the primary unavoidable waste product. Eventually, plants use photosynthesis to convert the carbon in carbon dioxide back into new complex carbon molecules, releasing the oxygen back into the air and beginning the natural cycle of fossil fuel formation all over again.
The above illustration is of a series of nested boxes showing the relationship between the terms used to characterize fossil fuels. These terms are defined as:
- Total resources (identified and undiscovered) is really just a mental anchor for these discussions. Geologists can provide a rough ballpark estimate of the total resources of a particular fuel, e.g., coal, but this is really just a guess.
- Identified resources in place is the estimate of the known resources of a particular fuel type within a defined geographic area, generally the land area of a nation and, possibly, its surrounding ocean.
- Available resources is that portion of the identified resources in-place that can be extracted in accordance with political, legal, and regulatory constraints.
- Technically-recoverable resources is that portion of the available resources that can be extracted using available technical means and done per existing safety and environmental regulations. The ability to produce the fuel profitably may or may not be a consideration in making the estimate of the technically-recoverable resources. The size of the technically-recoverable resources is defined by the U.S. Government as the nation’s “endowment” of fossil fuels and is, hence, appropriate to use in energy security planning.
- Economically recoverable resources (proved reserves) is the portion of the technically-recoverable reserves/resources that can be produced profitably at current market, legal, and regulatory conditions. Proved reserves—the terminology typically used— are normally owned or controlled by private industry.
In Fig. 11, the small arrows reflect the fact that these estimates change as more field data is collected and analyzed, as market, legal, and regulatory conditions change, and as new extraction technologies are introduced, e.g., hydraulic fracturing.
The large arrow represents what is referred to as the recovery factor. This is the percentage of the identified resources in place that can be permissibly extracted with available technologies. This percentage ranges from about 55% for coal, to 50-60% for conventional oil (with enhanced recovery methods), and to 80-90% for conventional natural gas. For oil and natural gas located in shale and tight rock formations—accounting for the recent boom in domestic oil and natural gas production and where guided drilling and hydraulic fracturing are required to be used—the recovery factor can be much lower—often less than 20%.
B. The U.S. fossil fuel endowment is about 1.4 Trillion BOE
From a strategic energy security perspective, understanding how much technically-recoverable fossil fuel resources the United States has is critical. Figure 12 shows the summary table from a 2011 study done by the Congressional Research Service. The report estimates that the United States has a remaining “endowment” of 1,366.8 billion BOE of technically recoverable resources. This includes economically recoverable resources (proved reserves) plus that portion of known and undiscovered technically recoverable resources thought by the Government to be profitable to produce. For example, the 261 billion short tons (2000 lbs.) of coal included in this endowment reflects only that portion of 486 billion short tons of available resources—called “demonstrated reserve base” in coal industry terminology—thought by the Government eventually to be profitable to produce.
- Oil shale is not the same as the “shale oil” being recovered from shale and tight rock formations using guided drilling and hydraulic fracturing. Oil shale is actually a primitive form of petroleum called kerogen. This is viscous goo found in some porous rock formations. While the United States is thought to have on the order of 1 trillion BOE of oil shale, the technologies to produce this economically with adequate environmental protections have not yet been developed. This author believes that oil shale is best thought of as a true strategic oil reserve to be tapped only if energy supply circumstances become dire.
- Exploration has determined that the world has immense stores of methane locked in a form of water ice called methane hydrates. When formed under high pressure in the presence of methane in the water, the water ice forms around a methane molecule, locking the methane into the ice. To recover the methane, the ice needs to be melted. The typical deep locations of the methane hydrate under the seafloor, the diffuse distribution of the methane hydrate, and the likely significant environmental impact of methane recovery is thought, by the author, to make this fossil fuel resource uneconomical/socially unacceptable to produce in substantial quantities. Hence, it is not appropriate to include this in U.S. energy security planning.
With these perspectives on oil shale and methane hydrates, the Congressional Research Service’s endowment estimate of 1.4 trillion BOE is a reasonable estimate to use in assessing U.S. fossil fuel energy security.
C. The U.S. fossil fuel endowment is far less than needed to remain energy secure through 2100
Recall that the United States used just shy of 1 trillion BOE of gross thermal energy from 1850-2010. With this in mind, the endowment of nearly 1.4 trillion BOE does sound like the United States has satisfyingly large remaining useable fossil fuel resources. But is this really the case considering that the U.S. population will likely more than double by 2100?
Of the 1.4 trillion BOE endowment, 261 billion short tons or 900 billion BOE comes from coal. The United States is currently producing about 1 billion short tons of coal per year with almost all used for electricity generation. Keeping this rate of coal production constant would consume about 90 billion short tons—about 310 billion BOE—of coal through 2100.
If we assume that all of the endowment’s oil and natural gas—shown in Fig. 12—would be extracted by 2100, the total fossil fuels produced through 2100 would total about 776 billion BOE.
162 billion BOE of oil + 304 billion BOE of natural gas
+ 310 billion BOE of coal = 776 billion BOE
Of the 2.23 trillion BOE needed through 2100, let us assume that nuclear and terrestrial renewables continue to provide 15%. The balance of 85% would need to come from fossil fuels. As shown in the following computation, the United States would have an energy supply shortfall of 1.2 trillion BOE—about 53% of what is needed.
2,230 billion BOE needed through 2100 x 0.85
– 776 billion BOE of fossil fuels extracted through 2100
= 1,179 billion BOE shortfall
Not good enough is it?
Let us assume a crash program—and a substantial relaxation of environmental regulations—to boost coal production so that the entire coal endowment of 900 billion BOE is extracted by 2100. In other words, let us assume the entire fossil fuel endowment of 1,367 billion BOE would be extracted by 2100. This still yields a shortfall of 529 billion BOE or about 24% of the total needed.
2,230 billion BOE needed through 2100 x 0.85
– 1,367 billion BOE of fossil fuels extracted through 2100
= 529 billion BOE shortfall
This “what if” analysis indicates that even with a crash program to mine all of the technically-recoverable coal, the United States would exhaust its useable/affordable fossil fuel supplies well before 2100—within the lifetime of our children and grandchildren. As a result, U.S. annual energy supplies would dramatically fall unless some means of substantially increasing imported energy were possible. But that would also increase U.S. energy insecurity, just as happened with oil in the 1970s, and would force the United States to compete with other nations of growing economic power, e.g., China, for these resources.
Consequently, continuing forward on today’s path of a substantial reliance on fossil fuels with no useful transition strategy to replacement energy sources is folly, is it not? It is a sure path to catastrophe that needs to be avoided. Thus, with the information available—U.S. energy needs through 2100 and the size of the U.S. endowment of fossil fuels—what path forward makes sense?