I should warn you that this section is filled with numbers and statistics. If you want the short version, what it basically says is that we use too much fossil fuels
producing energy, and it is going to get worse. As a result, we produce too much CO2, with serious consequences for global warming. Renewable energy sources are not sufficient to make a big dent in our use of fossil fuels, either now or in the future. Now for the numbers (or skip to the next chapter, but really you shouldn’t!).

The total yearly demand for energy in the United States is currently about 95 qua­drillion BTUs (quads),4 according to the US Energy Information Administration (EIA). The vast majority (82%) of this energy comes from three different fossil fuels: petroleum, natural gas, and coal. Nuclear reactors contribute about 8.5%, and renewable energy contributes 9.3% (Figure 2.1) (12). The renewable energy component is a bit misleading, since most people think of renewable energy as wind and solar. Actually, the renewable energy component is derived from several different sources, with biomass (mostly wood and corn-based ethanol) being the largest at 4.6%, followed by hydroelectric (2.8%), wind (1.4%), solar (0.25%), and geothermal (0.24%).

The other big factor to consider is how we use the energy. These various sources of energy are used for transportation, to run industries, to heat and cool residences and commercial buildings, and to generate electricity (Figure 2.2). The largest use of petroleum is for transportation, though about one-quarter is used for industrial processes and 5% for residential and commercial consumption. Only about 1% of petroleum is used for electric power production. Natural gas is used in roughly equal proportions for electric power production, industrial processes, and resi — dential/commercial heating with about 3% used for transportation. Over 90% of coal is used for electric power with about 8% for industrial processes. Nuclear

Nuclear,

8.5%

Renewable Energy, 9.3%

Petroleum,

36.5%

Coal, 18.3%

Natural gas,
27.3%

Figure 2.1 Sources of energy for the United States in 2012. The total amount of energy was about 100 quads, so each percentage is also roughly the amount in quads. source: Data from EIA, Monthly Energy Review May 2013.

reactors are used entirely for electric power generation, while renewable energy is divided among all four uses, with half going to electric power (13).

What insights can we gain from this information about energy sources and uses? One important point is that petroleum accounts for about 36% of US energy and 45% of that is imported, so about 15% of all US energy is imported. This is a dramatic change from just a few years ago, when over 60% of petroleum was imported (14). The decrease in imports is because of both increased production and decreased use of petroleum. Another major point is that 84% of our energy comes from fossil fuels, and all fossil fuels produce CO2. This is an inevitable con­sequence of the fact that, no matter how “clean” or efficient the process, burning any source of hydrocarbon ultimately produces CO2 and water. Natural gas burns more cleanly than petroleum or coal, but it still produces about half as much CO2 as that produced by burning coal because of the difference in energy den­sity; burning petroleum produces an intermediate amount of CO2 for the same amount of energy produced.5 Thus, the idea of “clean” fossil fuels is an oxymoron because you can’t get away from the production of CO2, which will produce global climate change, as described in Chapter 1.

Another obvious but important point is that different sources are important in different applications. Most petroleum products are used for transportation, so reducing the use of petroleum will require much greater efficiency in automobiles. Petroleum is also the only source of energy that is largely imported rather than produced in the United States, which has major geopolitical consequences, so there is more than one good reason to reduce dependence on petroleum. Coal, on the other hand, is used almost exclusively for electric power production, so its use can be reduced by conservation and by producing electricity with nuclear power plants and renewable energy sources. These two factors are not unrelated, though.

Increasing the efficiency of automobiles is expected to be done in part by pro­ducing electric cars that can be plugged into the electrical grid. But where does the power come from to charge the batteries of the electric cars? If it comes from coal, the problem is equally bad or worse, not better. According to a US Department of Energy study, both all-electric vehicles and plug-in hybrids generate more CO2 than a regular hybrid in the Midwest and eastern United States because of the greater dependence on coal for electricity to power the cars (15). Furthermore, if a large fraction of the US automobile fleet were electric cars, it would impose a very large additional electrical energy demand, which would require many more power plants.

Now let’s look more closely at where we get electrical power, since that is the focus of this book. More than 40% of the total energy usage in the United States is devoted to the production of electricity, with the majority coming from fos­sil fuels. Coal provides 41% of the energy to produce that electricity, natural gas provides 24%, and petroleum provides 1%, so 66% of our electricity generation comes from fossil fuels that produce CO2 (Figure 2.3). Nuclear reactors provide 21% of our electric power, and renewable energy provides 12%. Of that 12%, 57% comes from hydropower, with wind and solar contributing only 29% and 0.9%, respectively. Thus, as of the end of 2012, wind provides 3.6% and solar provides 0.11% of the electric power in the United States (12). These renewable energy sources have a very long way to go to make up a significant part of the total energy portfolio for the United States.

What can we expect for the future? Are wind and solar power going to be able to make a big dent in the amount of coal that is used to produce electricity? The

EIA produces a report every year that assesses current energy usage and proj­ects usage and sources into the future. The latest report (Annual Energy Outlook 2013) makes projections into 2040 (14). According to their reference report, which takes into account current laws but does not consider future policies that may change, the total energy consumption will increase 10% from 98 quads in 2011 to 108 quads by 2040. Of that total energy, 78% will be provided by fossil fuels from coal, oil, and natural gas, which represents an actual increase in fossil fuel usage of about 5 quads. Most of this increase comes from increased natural gas produc­tion. Electricity usage goes up even faster than total energy usage, increasing 31% by 2040. You might think that energy conservation and efficiency will prevent this from happening, but these projections already include a 46% reduction in energy intensity6 compared to 2011. Even with substantial increases in renewable energy, going from 10% to 14% of electrical generation for the United States, the use of coal still goes up about 5% from 2011 to 2040. Still, there is some good news. Because of the increased use of natural gas and greater efficiency, energy-related CO2 emissions are expected to be 5% less in 2040 than they were in 2005.

Many states require a large increase in renewable energy for electricity gen­eration through what are known as renewable portfolio standards. My state of Colorado mandates that 30% of electricity must be generated by renewable sources by 2020; California mandates that 33% of its electricity be generated by renewable sources by 2020. Making a law and actually doing it are two very dif­ferent things, though. The difficulties of meeting these targets will be discussed in Chapter 4.