Plant Biomass as a Substitute for Oil in Transportation

As discussed in Chapter 3, the transportation sector accounts for approximately a third of total emissions of CO2 in the United States, with a smaller fraction but a rapidly growing total in China. Combustion of oil, either as gasoline or diesel, is primarily responsible for the transportation- related emissions of both countries. Strategies to curtail overall emissions of CO2 must include plans for a major reduction in the use of oil in the transportation sector. This could be accomplished (1) by reducing demand for trans¬portation services; (2) by increasing the energy efficiency of the sector; or (3) by transitioning to an energy system less reliant on carbon- emitting sources of energy. Assuming continuing growth in the economies of both countries, option 1 is unlikely, certainly for China. Significant success has been achieved already in the United States under option 2, prompted by the application of increasingly more stringent corporate average fuel economy (CAFE) standards. And the technological advances achieved under this program are likely to find application in China and elsewhere, given the global nature of the automobile/ truck industry. The topic for discussion in this chapter is whether switching from oil to a plant- or animal- based fuel could contribute to a significant reduction in CO2 emissions from the transportation sector of either or both countries, indeed from the globe as a whole. The question is whether plant- based ethanol can substitute for gasoline and whether additional plant- and animal- derived products can cut back on demand for diesel. The related issue is whether this substitution can contribute at acceptable social and economic cost to a net reduction in overall CO2 emissions when account is taken of the entire lifecycle for production of the nonfossil alternatives. There is an extensive history to the use of ethanol as a motor fuel. Nicolas Otto, cred¬ited with the development of the internal combustion engine, used ethanol as the energy source for one of his early vehicle inventions in 1860. Henry Ford designed his first auto¬mobile, the quadricycle, to run on pure ethanol in 1896.

Hydro: Power From Running Water

As discussed in Chapter 4 and illustrated in Figure 4.1, close to 50% of the solar energy intercepted by the Earth is absorbed at the surface. Approximately half of this energy, 78 W m– 2, is used to evaporate water, mainly from the ocean. What this means is that evaporation of water accounts for as much as a third of the total solar energy absorbed by the Earth (atmosphere plus surface). The atmosphere has a limited ability to retain this water. Evaporation is balanced in close to real time by precipitation. A portion of this precipitation reaches the surface in regions elevated with respect to sea level— in mountainous locations, for example. It is endowed in this case with what we refer to as potential energy (Chapter 4). This potential energy can be stored (in lakes or dams, for instance), or it can be released, converted to kinetic energy (directed motion) as the water flows downhill on its return to the ocean. And along the way, energy can be captured and channeled to perform useful work. An early application involved exploiting the power of running water to turn a flat stone, one of two that constituted the apparatus used to grind grain, the other remaining stationary during the grinding process. The Domesday Book records that by AD 1086 as many as 5,624 water mills were operational in England south of the River Trent, deployed not just to grind grain but for a multitude of other tasks, including, but not confined to, sawing wood, crushing ore, and pumping the bellows of industrial furnaces (Derry and Williams 1960). Later, running water would provide the motive force for the textile industry that marked the beginning of the industrial age in North America, specifically in New England (Steinberg 1991; McElroy 2010). The most important contemporary application of water power involves the generation of electricity, the bulk of which is obtained by tapping the potential energy stored in high- altitude dams, a lesser fraction from the kinetic energy supplied by free- flowing streams (what is referred to as run- of- the- river sources).

The Contemporary US Energy System Overview Including A Comparison With China

The discussion in chapter 2 addressed what might be described as a microview of the US energy economy— how we use energy as individuals, how we measure our personal consumption, and how we pay for it. We turn attention now to a more expansive perspective— the use of energy on a national scale, including a discussion of associated economic benefits and costs. We focus specifically on implications for emissions of the greenhouse gas CO2. If we are to take the issue of human- induced climate change seriously— and I do— we will be obliged to adjust our energy system markedly to reduce emissions of this gas, the most important agent for human- induced climate change. And we will need to do it sooner rather than later. This chapter will underscore the magnitude of the challenge we face if we are to successfully chart the course to a more sustainable climate- energy future. We turn later to strategies that might accelerate our progress toward this objective.We elected in this volume to focus on the present and potential future of the energy economy of the United States. It is important to recognize that the fate of the global climate system will depend not just on what happens in the United States but also to an increasing extent on what comes to pass in other large industrial economies. China surpassed the United States as the largest national emitter of CO2 in 2006. The United States and China together were responsible in 2012 for more than 42% of total global emissions. Add Russia, India, Japan, Germany, Canada, United Kingdom, South Korea, and Iran to the mix (the other members of the top 10 emitting countries ordered in terms of their relative contributions), and we can account for more than 60% of the global total. Given the importance of China to the global CO2 economy (more than 26% of the present global total and likely to increase significantly in the near term), I decided that it would be instructive to include here at least some discussion of the situation in China— to elaborate what the energy economies of China and the United States have in common, outlining at the same time the factors and challenges that set them apart.

Introduction

The risk of disruptive climate change is real and immediate. A low- pressure system forming in the tropics develops into a Category hurricane, 1 making its way slowly up the east coast of the United States. Normally a storm such as this would be expected to make a right- hand turn and move off across the Atlantic. Conditions, however, are not normal. This storm is about to encounter an intense low- pressure weather system associated with an unusual configuration of the jet stream, linked potentially to an abnormally warm condition in the Arctic. Forecasts suggest that rather than turning right, the storm is going to turn left and intensify as it moves over unseasonably warm water off the New Jersey coast. It develops into what some would describe as the storm of the century. New York and New Jersey feel the brunt of the damage. The impact extends as far north as Maine and as far south as North Carolina. Lower Manhattan is engulfed by a 14- foot storm surge, flooding the subway, plunging the city south of 39th Street into darkness. Residents of Staten Island fear for their lives as their homes are flooded, as they lose power, and as their community is effectively isolated from the rest of the world. As many as 23 people are drowned as floodwaters engulf much of the borough. Beach communities of New Jersey are devastated. As much as a week after the storm has passed, more than a million homes and businesses in New York and New Jersey are still without power. Estimates of damage range as high as $60 billion. This is the story of the devastation brought about by Hurricane Sandy in late October of 2012.The encounter with Sandy prompted a number of queries concerning a possible link to human- induced global climate change. Andrew Cuomo, governor of New York, commented: “Part of the learning from this is the recognition that climate change is a reality, extreme weather is a reality.”

Earth Heat and Lunar Gravity Geothermal And Tidal Energy

To this point, we have discussed the current status and future prospects of energy from coal, oil, natural gas, nuclear, wind, solar, and hydro. With the exception of the contribution from nuclear, the ultimate origin of the energy for all of these sources is the sun— energy captured millions of years ago by photosynthesis in the case of the fossil fuels (coal, oil, and natural gas), energy harvested from contemporary inputs in the case of wind and solar. We turn now to a discussion of the potential for generation of electricity from geothermal sources and ocean tides. Decay of radioactive elements in the Earth’s interior provides the dominant source for the former; energy extracted from the gravitational interaction of the Earth and moon is the primary source for the latter. There are two main contributions to the energy reaching the surface from the Earth’s interior. The first involves convection and conduction of heat from the mantle and core. The second reflects the contribution from decay of radioactive elements in the crust, notably uranium, thorium, and potassium. The composite geothermal source, averaged over the Earth, amounts to about 8 × 10– 2 W m– 2, approximately 3,000 times less than the energy absorbed from the sun. As a consequence of the presence of the internal source, temperatures increase at an average rate of about 25°C per kilometer as a function of depth below the Earth’s surface. The rate of increase is greater in regions that are tectonically active, notably in the western United States and in the region surrounding the Pacific Ocean (the so- called Ring of Fire) — less in others. Of particular interest in terms of harvesting the internal energy source to produce electricity are hydrothermal reservoirs, subsurface environments characterized by the presence of significant quantities of high- temperature water formed by exposure to lava or through contact with unusually hot crustal material. The water contained in hydrothermal reservoirs is supplied for the most part by percolation from the surface through overlying porous rock. The conditions required for production of these hydrothermal systems are relatively specialized.

Coal: Abundant But Problematic

coal accounted for 30.3% of total global energy consumption in 2011, the highest share since 1969 (BP 2012a). Since coal on a per unit energy basis is the most prolific of the fossil fuels in terms of CO2 emissions, this fact alone underscores the magnitude of the challenge we face in addressing the climate issue. Emissions of CO2 from oil and natural gas, expressed on a per unit energy basis, amount to approximately 78% and 54% of those from coal. In 2010, 43% of global CO2 emissions were derived from coal, 36% from oil, and 20% from natural gas. China was responsible for 49.3% of total coal consumed worldwide in 2011. The United States (13.5%), India (7.9%), and Japan (3.2%) ranked 2 through 4. Consumption in the Asian Pacific region amounted to 71.2% of the global total in 2011, as compared to 14.3% in North America (the United States, Canada, and Mexico) and 13.4% in Europe and Eurasia (including the Russian Federation and Ukraine). Coal accounted for 70% of total energy use in China in 2011 (65.5% in 2013), as compared to 22% in the United States. Use of coal increased in China by 9.7% in 2011 relative to 2010. In contrast, consumption in the United States declined by 0.46% over the same period. BP (2012b) projects that demand for coal in OECD countries will decrease by 0.8% per year between 2011 and 2030. The projected falloff in OECD countries is offset by growth of 1.9% per year over the same time interval in non- OECD countries. China, in the BP projection, remains the world’s largest consumer of coal in 2030 (52% of total global consumption). The growth rate in China is expected to drop, though, from 9% per year over the decade 2000 to 2010, to 3.5% between 2010 and 2020, falling further to 0.4% between 2020 and 2030. The trend, as indicated in the BP analysis, reflects the assumption of a shift to less coal- intensive economic activities, combined with an improvement in overall energy efficiency. India is projected to surpass the United States in terms of total demand for coal by 2024.

Human- Induced Climate Change Arguments Offered By Those Who Dissent

Chapter 4 presented an extensive account of current understanding of climate change. The evidence that humans are having an important impact on the global climate system is scientifically compelling. And yet there are those who disagree and refuse to accept the evidence. Some of the dissent is based on a visceral feeling that the world is too big for humans to have the capacity to change it. Some is grounded, I believe, on ideology, on an instinctive distrust of science combined with a suspicion of govern¬ment, amplified by a feeling that those in authority are trying to use the issue to advance some other agenda, to increase taxes, for example. More insidious are dissenting views expressed by scientists on the opinion pages of influential newspapers such as The Wall Street Journal (WSJ). If scientists disagree, the implication for the public is that there is no urgency: we can afford to wait until the dust settles before deciding to take action— or not, as the case may be. Missing in the discourse triggered by these communications is the fact that, with few exceptions, the authors of these articles are not well informed on climate science. To put it bluntly, their views reflect personal opinion and in some cases explicit prejudice rather than objective analysis. Their communications are influential, nonetheless, and demand a response. I begin by addressing some of the general sentiments expressed by those who are either on the fence as to the significance of human- induced climate change or who may already have made up their minds that the issue is part of an elaborate hoax to mislead the public. There are a number of recurrent themes: The data purporting to show that the world is warming have been manipu-lated by climate scientists to enhance their funding or for other self- serving reasons.Climate science is complicated; scientists cannot predict the weather. Why should we believe that they could tell us what is going to happen a decade or more in the future? The planet has been warmer in the past; we survived and maybe even prospered.

Vision for a Low- Carbon- Energy Future

This chapter discusses steps that could be taken to realize the long- term goal of reducing, if not eliminating, climate- altering emissions associated with the consumption of coal, oil, and natural gas. I choose to focus on initiatives that could be adopted over the next several decades to advance this objective in the United States. The key elements of the vision proposed for the United States should be applicable, however, also to China and to other large emitting countries. As indicated at the outset, the overall focus in this volume has been on the United States and China, the world’s largest emitters of greenhouse gases, recognizing at the same time differences in states of development and national priorities of the two countries. The vision I outline here for a low- carbon-energy future for the United States should apply also to other countries. The time scale for implementation may differ, however, from country to country, depending on details of local conditions and priorities— economic, social, and environmental. The data presented in Chapter 3 (Figs. 3.1 and 3.2) provide a useful starting point— essential background— for discussion of potential future scenarios (US EIA 2015). They define how energy is used in the current US economy and the services responsible for the related emissions, with key data summarized in Table 16.1. Generation of electricity was responsible for emission of 2,050 million tons of CO2 in 2013, 1,580 million tons from combustion of coal, and 442 million tons from natural gas, with a minor contri-bution, 34.7 million tons, from oil. The residential, commercial, and industrial sectors accounted, respectively, for 38%, 36%, and 26% of emissions associated with economy-wide consumption of electricity. The power sector was responsible for 38% of total national emissions. Transportation contributed an additional 1,826 million tons, 34% of the national total. The bulk of the emissions from transportation (98%) was associated with consumption of petroleum products, gasoline, diesel fuel, and jet fuel, with the balance from natural gas

Limiting US And Chinese Emissions: The Beijing Agreement

In a landmark agreement reached in Beijing on November 11, 2014, US President Obama and his Chinese counterpart President Xi Jinping announced plans to limit future emissions of greenhouse gases from their two countries. President Obama’s commitment was for the United States to emit 26% to 28% less carbon in 2025 than it did in 2005, a target more ambitious than one he had announced earlier (in 2009) that would have called for a decrease of 17% by 2020. The prior target would have required a reduc¬tion in emissions at an annual average rate of 1.2% between 2005 and 2020. The more recent agreement dictates a faster pace, at least in the later years, 2.3%– 2.8% per year between 2020 and 2025. The longer term goal for US climate policy, announced at the Climate Change Summit in Copenhagen in 2009, is to reduce emissions by 83% by 2050 relative to 2005. President Xi’s commitment in Beijing was that China’s emissions would peak by 2030, if not earlier, and that nonfossil sources would account for as much as 20% of China’s total primary energy consumption by 2030. As indicated in the fact sheet released by the White House describing the agreement (http:// www.whitehouse.gov/ the- press- office/ 2014/ 11/ 11/ fact- sheet- us- china- joint- announcement- climate- change- and- clean- energy- c), Xi’s pledge would require “China to deploy an additional 800–1,000 GW of nuclear, wind, solar, and other zero emission generation capacity by 2030— more than all of the coal- fired plants that exist in China today and close to total current electricity generat¬ing capacity in the United States.” in a landmark agreement reached in Beijing on November 11, 2014, US President Obama and his Chinese counterpart President Xi Jinping announced plans to limit future emissions of greenhouse gases from their two countries. President Obama’s com¬mitment was for the United States to emit 26% to 28% less carbon in 2025 than it did in 2005, a target more ambitious than one he had announced earlier (in 2009) that would have called for a decrease of 17% by 2020.

Power from the Sun Abundant But Expensive

As discussed in the preceding chapter, wind resources available from nonforested, nonurban, land-based environments in the United States are more than sufficient to meet present and projected future US demand for electricity. Wind resources are comparably abundant elsewhere. As indicated in Table 10.2, a combination of onshore and offshore wind could accommodate prospective demand for electricity for all of the countries classified as top- 10 emitters of CO2. Solar energy reaching the Earth’s surface averages about 200 W m– 2 (Fig. 4.1). If this power source could be converted to electricity with an efficiency of 20%, as little as 0.1% of the land area of the United States (3% of the area of Arizona) could supply the bulk of US demand for electricity. As discussed later in this chapter, the potential source of power from the sun is significant even for sun- deprived countries such as Germany. Wind and solar energy provide potentially complementary sources of electricity in the sense that when the supply from one is low, there is a good chance that it may be offset by a higher contribution from the other. Winds blow strongest typically at night and in winter. The potential supply of energy from the sun, in contrast, is highest during the day and in summer. The source from the sun is better matched thus than wind to respond to the seasonal pattern of demand for electricity, at least for the United States (as indicated in Fig. 10.5).There are two approaches available to convert energy from the sun to electricity. The first involves using photovoltaic (PV) cells, devices in which absorption of radiation results directly in production of electricity. The second is less direct. It requires solar energy to be captured and deployed first to produce heat, with the heat used subsequently to generate steam, the steam applied then to drive a turbine. The sequence in this case is similar to that used to generate electricity in conventional coal, oil, natural gas, and nuclear- powered systems. The difference is that the energy source is light from the sun rather than a carbon- based fossil fuel or fissionable uranium.