Can anything be done to avoid such a drastic increase in CO2? The World Energy Outlook 2009 report presents an alternative scenario to the reference scenario described above; this alternative is intended to reduce CO2 emissions to 26.4 Gt, which would give an atmospheric concentration of 450 ppm by 2030. This ambi­tious scenario involves reducing coal usage below 2008 levels, a slight rise in oil,

and a substantial increase in natural gas. This is made up by large increases in biomass, nuclear, and other renewable energy sources (Figure 2.5). The largest reduction in CO2, though, comes from increased efficiency in how energy is pro­duced and used (17). This scenario is expected to cost many trillions of dollars, and keep in mind that 450 ppm CO2 may well be too high a target. As described in Chapter 1, Jim Hansen and others are convinced that we should be aiming for 350 ppm CO2.

I n March 2008 the US National Academy of Sciences held a summit on America’s energy future that involved wide-ranging discussions on the problem of global warming and what can be done to reduce our emissions of CO2 (4). One approach to reduce CO2 emissions to pre-1990 levels by the year 2030 is based on an analysis done by the Electric Power Research Institute (EPRI), an independent, nonprofit organization that conducts research on the generation, delivery, and use of electricity. Greater efficiency would limit the increase in electricity con­sumption to 0.75% per year instead of the 1% increase projected by the EIA 2008 reference scenario (Figure 2.6). Renewable energy would increase to 100 GWe, while nuclear power would increase by an additional 64 GWe from its current 100 GWe. Coal continues to be a dominant source, but efficiency improvements of coal power plants, both existing and new, reduce demand for coal, and carbon capture and storage technology would be widely deployed. There would be a shift to plug-in hybrid electric vehicles (one-third of new cars by 2030) and distributed energy resources, such as solar panels on houses, would contribute 5% of the base electricity load (23).

An alternative analysis of abatement of greenhouse gas (GHG) emissions worldwide was done by McKinsey & Company, a business consultancy firm that provides critical analyses of a variety of issues. Their 2009 report highlights a large number of steps that can be taken to reduce GHGs and estimates the cost of pro­viding each part of that reduction (24). An updated report to account for the reduction in energy demand due to the global recession was published in 2010 (25). The authors examined more than 200 different options in 10 sectors and

3500

21 world regions for reducing GHGs and then calculated the potential GHG abatement and the cost for each category. The result is a widely reproduced chart that illustrates the different options and their cost-effectiveness per ton of GHG abated (Figure 2.7). This analysis shows the potential to reduce GHGs by 35% below 1990 levels by 2030, or 70% below the expected levels in 2030, with business as usual. Capturing the full abatement potential should hold the expected global temperature increase to 2°C, which may be a critical threshold temperature (see Chapter 1).

What are the categories that provide the biggest bang for the buck? The total world annual GHG emissions are projected to be 66 Gt CO2e (carbon diox­ide equivalents) by 2030 with business as usual. This is larger than the num­bers given above because it includes other greenhouse gases, such as methane and nitrous oxide, and it also includes emissions from agriculture and loss of forests and grasslands. Efficiency steps are relatively cheap but provide rela­tively small reductions individually. In aggregate they provide a 14 Gt reduc­tion in GHG emissions. Energy production accounts for about one-quarter of the world total of GHGs, almost entirely as CO2. Changing energy production from carbon-intensive sources to renewable and nuclear provides a reduc­tion of 12 Gt CO2e. Nuclear power is more cost-effective in reducing CO2 than either wind or solar power, though both play an important role. The report assumes that carbon capture and storage technology will exist and will make a big impact in reducing CO2 from coal. Other reductions in the report are

Global GHG abatement cost curve beyond business-as-usual (v2.1) — 2030

Note: The curve presents an estimate of the maximum potential of all technical GHG abatement measures below €80 per tCO2e if each lever was pursued aggressively. It is not a forecast of what role different abatement measures and technologies will play.

Source: McKinsey & Company: The impact of the financial crisis on carbon economics — Version 2.1 of the Global Greenhouse Gas Abatement Cost Curve

F igure 2.7 Strategies to reduce greenhouse gases and the relative cost for each strategy. The width of each bar represents the amount of GHG abatement, and the vertical height is the cost per ton of CO2 equivalent.

source: Reproduced by permission from McKinsey & Company 2010 (Impact ofthe Financial Crisis on Carbon Economics:Version 2.1 ofthe Global Greenhouse Gas Abatement Cost Curve).

associated with agricultural practices and deforestation and will not be dis­cussed further in this book.

In my view, the biggest problem with the scenario for electric power genera­tion is with the carbon capture and storage technology, which will be discussed in the next chapter. This contributes the largest single factor in reducing CO2 in the EPRI analysis. If that does not occur, there would have to be very large reductions in demand for electricity with essentially no increase for 40 years, and natural gas would have to be used to replace the coal that would be phased out. An alternative to this would be to increase the use of nuclear power to an even greater degree so that coal can be phased out. Is this feasible for an industrialized country? France gets 75% of its electricity from nuclear power and has the third lowest per capita CO2 emissions of any Western European country (after Sweden and Switzerland) (16). Both Sweden and Switzerland are slightly lower because they get 40% of their electricity from nuclear power and nearly all the rest from hydropower (26, 27). All three countries emit about the same amount of CO2 per capita as China and about one-third as much as the United States.

Our discussion thus far has provided some background: where our energy comes from, what it is used for, future projections if we don’t make major changes in energy production and usage, and the major possibilities for reducing the pro­duction of CO2 to minimize global climate change. In the following chapters we will explore the various issues associated with each major source of energy, espe­cially coal, natural gas, wind, solar, and nuclear.

NOTES

1. Remarkably, recent events seem to follow history. On April 20, 2010, a mile-deep oil well in the Gulf of Mexico suffered a gas explosion and fire that killed eleven men and led to an environmental disaster.

2 . Power is given in units of watts, kilowatts (kW), megawatts (MW) and gigawatts (GW). Energy is the amount of power produced multiplied by the time over which it is produced. For example, power is in kW and energy is in kilowatt hours (kWh). A given amount of coal or other energy source has a given amount of energy that can be converted into power. Only about one-third of the energy in coal can be converted into electrical power, with the rest going into heat. Power plants are usu­ally rated by the amount of electric power they produce, given in MWe or GWe (for electric). See Appendix B for more details.

3. Nuclear fusion has the potential of even greater energy density, but is not available and is unlikely to be a source of usable energy for the next 50-100 years, if ever (11).

4. BTU (British thermal units) is a unit of energy. 1 quad (quadrillion BTU) equals 1015 BTU, which equals 2.93 x 108 (293 million) MWh. See Appendix B for more information about energy units.

5. The amount of CO2 produced is 3.7 times as much as the carbon burned because of the addition of two oxygen atoms for each carbon atom. Since the coal used in power plants (bituminous and sub-bituminous) is only 35-85% carbon, the amount of CO2 produced by burning a ton of coal ranges from 1.3 to 3.1 tons.

6. Energy intensity is the primary energy use per dollar of GDP (gross domestic prod­uct). It is essentially a measure of energy efficiency. As energy is used more effi­ciently, the energy intensity becomes smaller.

7. The Organisation for Economic Co-operation and Development consists of 34 countries devoted to democracy and the free market and includes mostly western European countries but also the United States, Canada, Australia, New Zealand, Japan, South Korea, Chile, and Mexico.