American Physics, Climate Change, and Energy
Wallace M. Manheimer
1. Introduction: American Physics Organizations and Climate Change
The issue of climate change is an important and polarizing one. For lack of better terms, I will call the two most extreme camps climate change alarmists and climate change deniers; most people are in-between. The American Physical Society (APS) has come out firmly in the camp of the alarmists. In 2007 it issued a statement that included the phrases "The evidence is incontrovertible: Global warming is occurring", and "We must reduce emissions of greenhouse gases beginning now" (1). It is unusual for a scientific society to offer such unwavering policy advice to society, and several APS members, including a Nobel-prize winner, resigned in protest. Objections included the belief that man-made global warming is not real, that the APS should not put itself in the position of giving unsolicited advice to society and governments, and that while global warming may be a problem, we still need energy (2, 3, 4, www.sepp.org). The APS reconsidered but ultimately reaffirmed its original statement, adding a lengthy explanation.
More recently, the American Institute of Physics published two articles in a single issue of its flagship publication, Physics Today, which made the case that global warming is a scientific certainty and we must take immediate action to prevent catastrophe (5,6). For instance, Ref. 5 dismisses all doubt with statements such as: "Greenhouse warming today faces an even greater array of bogus counterarguments based on the uninformed interpretation of data from ice cores, erroneous views about natural carbon sources, alleged but unobserved alternative drivers of climate change, naive expectations of the time scales over which models and observations should match, and various forms of statistical chicanery and logical fallacy." The alarmism in Ref. 6 is apparent by quotes such as: "The urgency of taking action to limit manmade climate change combines subjective considerations with scientific ones," "Some recent research suggests that severe climate change, including very large sea-level rises, can occur even with a 2 °C ceiling," and "The science tells us that meeting the policy goals requires urgent action." Figure 1 shows Figure 5 of reference (6): the necessary future course of carbon input into the atmosphere if we are to keep the total CO2 emissions to 750 Gt over the period 2010-2050. In all cases, carbon input into the atmosphere must end in about 30 years.
Figure 1: Three scenarios, each of which would limit the total global emission of carbon dioxide from fossil-fuel burning and industrial processes to 750 Gt over the period 2010–50
In the opinion of this author, there is a serious problem with this alarmism and proposed reductions scenario: That they almost certainly condemn the vast majority of the human family to abject poverty. Another inconvenient truth is that civilization and development need energy, and lots of it. As argued below, to bring much of the world to a reasonable level of prosperity would require some 10-30 terawatts (TW) of additional power, preferably carbon free, by around mid-century (7).
In this article, I advance the case that the standard 'renewable' energies, solar and sequestration, are nowhere near ready to provide for societal energy needs, and likely never will be. This leaves efficiency enhancement, nuclear reactors, and fossil fuels as possible sources. In the following sections, I examine the current status of worldwide energy use and carbon emissions (Sect. 2) and the circumstances for various possible carbon-free energy sources and fossil fuels (Sect. 3). Section 4 offers a brief summary and conclusion.
2. Energy and Civilization
To see the relation between energy use and civilization, Figure 2 shows yearly per capita energy use versus yearly per capita GDP in year 2000 for a number of countries. The two are very strongly correlated; there are no rich countries that use little energy per capita. Countries high up on the graph have more educated populations who live more pleasant, longer lives, and who live in cleaner environments than countries lower down on the graph. [Chart compiled by D. Lightfoot from information available from Energy Information Agency (EIA); see also www.mcgill.ca/ gec3/gec3members/lightfoot].
Figure 2: Annual energy consumption versus annual GDP per capita
Total world power use in 2005 was about 13 TW, about 85% of which derived from fossil fuel. The United States, which is home to about 5% of the world's population, uses about 2.5 TW. If we in the U.S. cut our energy use by 40%, our standard of living (going down parallel to the line) would be about like Italy's. Actually, it would be much worse because distances are much greater in the United States, it is colder here, and we have responsibilities as a major world power that Italy does not have. However, the undeniable and overriding goal of world development is presumably to bring all countries up the curve, so let us imagine that all people enjoyed an Italy-level standard of living. This would increase world power use to 30 TW in 2005 and to 50 TW by 2050 when the world population reaches 10 billion. Clearly, conservation, efficiency enhancement, and new sources of energy are essential for development to continue.
As regards carbon emissions, the Kyoto Accord mandates that each signatory reduce its carbon input to the atmosphere by 10% from its 1990 levels. Table 1 shows yearly carbon input to the atmosphere (in million of metric tons) from burning fuels, in both 1990 and 2005 for a number of countries. European countries in bold type are countries that have never been part of the Warsaw Pact.
Table 1, Carbon Emissions, millions of metric tons
|Sum of above||2166||2516||16%|
|Sum of above||2621||2129||-19%|
Source: Data is taken from the DoE web site, www.eia.doe.gov/environment/hmtl ; follow prompts to international emission data.
Several things are clear from this table. First, one way to decrease carbon input is to have a command economy, which has no regard for environmental standards, is uncoupled from a free market, and then suffers some form of collapse (Poland, Bulgaria, Romania, Russia). Second, other than former Warsaw pact countries, the only major country even close to meeting its Kyoto mandate is Britain, which completed a large change from coal to natural gas in the 1990's. Third, France emits less carbon than other European countries its size. The reason for this is that France has embraced nuclear power to a very great extent. Nuclear power really does reduce carbon emission, and is in fact affordable, at least for the French. Fourth, the role of developing countries is crucial as regards future carbon input. The cases of India and China are well known; in 2009 China became the world's largest carbon emitter. But other less well-known places are rapidly increasing their carbon input. Even tiny, impoverished Malawi, the lowest-named country in Figure 2, is unwilling to stay where it is. The poorer parts of the world will do whatever it takes to share in the life style we in the west enjoy, and who can blame them? A more prosperous world will make for a more peaceful one. In any event, despite Kyoto, Cancun, and Durban, the world certainly seems to be doing the carbon-input experiment. We had better hope the fears of the alarmists prove to be unfounded.
3. Possible carbon-free energy sources & fossil fuel
The requirement of 50 TW of carbon free power by mid century is daunting. Anything that can be done to reduce this number will make the task of energy supply much easier. Accordingly in Part A of this section, I look into efficiency enhancement. Part B examines nuclear power. It seems to this author that these are the two tall poles which could support mid-century civilization. In Part C I consider fossil fuel, which would play a lesser but still an important role. Then I examine other options, which likely will play much smaller roles. Solar power (actually direct solar, wind and biofuel) is discussed in Part D. Carbon sequestration is discussed in Part E. Generally, I do not give specific references for numbers given; these can be confirmed by internet searches.
3A. Efficiency and conservation
The APS has long been concerned with energy efficiency, and recently put out a report of a study group, chaired by Burton Richter (8). However, it is also important to realize that improving efficiency is the natural extension of a long-term trend of reducing the energy intensity. This is the power used (worldwide) divided by the world's inflation adjusted gross national product. It has been declining by about 1% per year over a long period (9). Enhanced efficiency and conservation are part of this. Reference 8 is concerned only with transportation and buildings in the United States; the concern of Reference(9) and this paper is worldwide.
As regards transportation, which uses about 20% of American power, Ref. (8) points out that without sacrificing safety or comfort, auto gas mileage could be increased from about 30 to 50 miles per gallon (p12). Part of this increase would come from reduction in weight, advances in materials, batteries, etc. Regarding buildings, which use about 40% of the nation's power, it speaks of improving efficiency up to 35% (p 60). Private buildings used about 45% of their power for space and water heating, mostly from fossil fuels in liquid or gaseous form, and 55% for other uses, mostly powered by electricity. For commercial buildings the fractions are about 25% and 75%. Enhanced efficiency might result from better insulation, windows, heating and cooling systems, and improved appliances. On-site elements of a more efficient building could be voltaic cells or solar water heaters on the roof.
3B. Nuclear Power
There are some 400 reactors in the world today, generating some 400 GWe (GWe is gigawatt electric, GWth is thermal, generally 3GWth~1GWe, due to Carnot efficiency). Many more are in various stages of construction and planning, and nuclear fission will surely play a significant role in meeting energy needs for decades to come. But we cannot ignore the recent Fukushima disaster. What should the response to Fukushima be? One approach is that of Germany, which has decided to decommission its 17 nuclear power plants which provide 23% of that nation's electricity. But then what will they do? Live without them and enormously increase the price of electricity? Build 17 coal fired plants? Install miles of solar collectors in cold, cloudy northern Europe? Install 17 GWe (50-60 GWe nameplate value) wind turbines, which may or may not provide power when it is needed? This would take up about 17,000 km2, about 5% of German land area (Sec. 3D). One possible scenario is that France builds 8-10 nuclear plants near their eastern border, while Poland builds an equal number of coal fired plants near their western border, and they both sell power to Germany. The Germans will then have clear consciences.
Fukushima should be regarded not only as a disaster but also as a learning experience. The lessons to be learned are beyond the expertise of this author, but might include the fact that the danger of a nuclear disaster is much more to land than to people, who have time to get away; do not locate nuclear plants in populated areas; have a second line of defense, such as generators nearby that could be moved in for cooling spent fuel, even in the midst of a chaotic situation; and do research to see if there are ways to decontaminate the land.
Other issues associated with nuclear energy are waste disposal, proliferation, and fuel supply. On the first two, the current science and engineering are ahead of societal acceptance. One method of dealing with actinide waste is to burn it with fast-neutron reactors (10). Until this technology is sufficiently mature (several of these demonstration reactors have been built at various power levels), one could store the waste in a geological repository such as Yucca Mountain, and remove it later for burning. Burning the actinide waste solves both the proliferation problem and a large part of the waste disposal problem. In this author's opinion, this would have to be a part of any sustainable nuclear option. The other part of the waste is the intermediate atomic number radioactive fission products. While highly radioactive, these pose no proliferation risk. Some have commercial value and could be separated out and sold. The rest could be left to decay over several centuries, a time human society can reasonably plan for. After a few centuries they will have decayed so much that they are basically inert.
The other problem with nuclear energy is fuel supply. Light-water reactors use only about 1% of the available fuel, the part of the ore that is 235U. Any sustainable option would have to find a way to use the rest. In this case, not only would all uranium be available for fuel, but all of the world's thorium would be as well; there is three times as much thorium as uranium. To get an idea of the magnitude of this resource, nuclear power has supplied about 400 GWe for about 40 years. Hence, in depleted uranium alone, there is fuel for 4 TWe for 400 years!
There are at least three approaches, in various stages of readiness, to using all the world's uranium and thorium. These are sodium-cooled fast neutron reactors such as the integral fast reactor (IFR) (10), molten salt thorium reactors (11), and breeding fuel via hybrid fusion, which has been advocated by this author (12). Research and development are required before any of these are ready for market. My own opinion is that such research has enormous upside potential. But whatever option or options are chosen, nuclear power does have the potential of supplying the world with carbon free power at 5-10 TWe safely, economically, environmentally soundly, and with negligible proliferation risk, at least as far into the future as the dawn of civilization was in the past.
3C. Fossil fuels
Civilization not only needs energy, it also needs liquid and gaseous fuel. Until manufactured fuel (i.e. hydrogen, ammonium,…) becomes economical and has an infrastructure in place, we are stuck with fossil fuel. There is no real substitute for transportation and space heating. While electricity might be used for space heating, it is inefficient. Fuel is turned to heat at the power plant, then one third of this heat is turned into electricity, two thirds are wasted, and then this electricity is converted back to heat at the building. The key is to minimize liquid fuel use via conservation and efficiency enhancement.
Conventional oil and gas, as well as newly economical supplies from shale and tar sands, are available and amenable to efficiency improvements. It is also important to note that coal can be converted to oil or gasoline via the Fischer- Tropsch or Berguis process. These were perfected by two nations cut off from the world oil market, Nazi Germany and South Africa during the apartheid era. The South African company, Sasol, still exists and China has contracted with it to produce 2 million barrels of oil or gas per day, in China, from Chinese coal (13). Thus fossil fuel, most likely without sequestration, would provide an important part of the energy budget. With enhanced efficiency in the transportation and building sector, and little use of solid coal to generate electricity, fossil fuel would be reduced, but not consigned to history.
3D. Solar-Derived Power: Direct Solar, Wind, and Biofuel
I treat direct solar, wind, and biofuel together here as, directly or indirectly, all have the sun as their source. Many of these approaches have received government subsidies in one way or another. But how does one measure and compare subsidies for various power sources? It is far from simple to do this. For example, a government which favors coal power might give a tax credit of $5 for every ton as a depletion allowance, whereas an environmentally conscious government might offer homeowners a subsidy of $100/year if they hook up to a wind power source. How can we compare these on some sort of level playing field?
One approach is to examine subsidies per kilowatt hour (kWh). Let us imagine, again hypothetically, that the total tax credit for coal is $20 billion and the total subsidy for wind power is $10 billion. Who gets the larger subsidy? Wind delivers about 10 GW in the United States, so its subsidy is about 10 cents per kWh. Coal delivers about 300 GW, so its subsidy is about 2/3 cent per kWh, much less than that for wind.
It is not easy to track down figures for government subsidies in cents per kWh, but some have been published. In 2002, Hydro Quebec subsidized wind power at a rate of 9 Canadian cents per kWh, as opposed to its commercial rate for hydro power of 3 cents per kWh (Hydro Quebec press release, Oct 4, 2002, www.hydroquebec.com). Eon-Netz, the largest wind power provider in Germany, had 7 GW of "nameplate" wind power installed in 2005, but only delivered about 1.3 GW to the grid, due to the intermittent nature of wind (www.eon-netz.com). It received a subsidy of about 9 Euro cents per kWh. The Japanese, in the wake of Fukushima, are understandably wary of nuclear power, and the government plans to subsidize wind power at 25 cents per kWh and solar voltaic power at 60 cents per kWh (14).
If the user were to pay the full cost in these scenarios, our electric bills would at least double, and more likely quadruple. I for one could not afford it. The scale of these subsidies leads one to believe that if they were removed, the most of these industries, would simply collapse, as Solyndra recently did, even with its large subsidy (15).
Any solar-derived power source is limited by two fundamental constraints: the incident solar power, and the efficiency by which that power is converted to electricity (or the desired format). At mid-latitudes at high noon on a sunny day, the solar power incident is about one kW/m2. However, averaging over day and night and over sunny and rainy periods, the average is about 200 W/m2, or about 200 MW/km2. In evaluating any of these schemes it is important to know whether the published power is the peak or the average power. In my own experience, it is almost always the peak, or nameplate power that is given, which makes the particular scheme look about four or five times more attractive than it really is.
Now let us consider the efficiencies of various solar energy sources. The most efficient is probably solar thermal, where a large number of mirrors focus the sun's rays on a small volume of liquid, heat it, and use this heat to run a generator and produce electricity. An advantage of this scheme is that mirrors are cheap compared to the high-tech surfaces needed for solar voltaic systems. The efficiency at which the solar heat is transferred to the liquid is about 70%, and the efficiency of producing electric power thermally is about 30%, so the total efficiency of solar to electricity is roughly 20%. An additional advantage of solar thermal is that the hot liquid can be stored and used to run a generator at night. However, there will almost certainly be at least some thermal losses at night, so the 20% is most likely an upper limit. Hence the potential for solar thermal is about 40 MWe/km2. A 1 GWe power station would occupy about 25 km2, and 1 TWe about 25,000 km2, an area about equal to the floor space of all buildings in the United States, assuming that each individual has 100 m2 in his house and workplace. Such systems would most likely be set up in dry, dusty, desert environments, where keeping the mirrors clean could be a challenge.
Solar voltaic systems use planar semiconductors to convert sunlight into electricity. Their conversion efficiency is about 10%, so they have about half the efficiency, and would take up about twice the land area of solar thermal systems. However, they convert directly to electricity without going through a thermal cycle. Further research might improve the efficiency of solar voltaic systems. The land devoted to large power stations could not be used for anything else, but small rooftop systems could use land more efficiently.
Wind power is more sporadic and less efficient than solar. Since the energy flux in the wind varies as the cube of the velocity, wind mills are only optimal for a narrow range of wind speeds. Too low a wind speed and there is insufficient power; too high and the turbine cannot handle it, and to protect itself goes off-line. Wind power has much more random variation than does solar thermal or solar voltaic. Accordingly, the average power generated is typically only about 1/5 of the nameplate value. It is not easy to determine the efficiency of wind installations, but empirically one can use the size of wind farms as compared to solar thermal farms to estimate how their efficiencies compare. An example is provided by the Elk River Wind farm near Beaumont, KS, a rather windy area of the country. It has a nameplate capacity of 150 MWe, and most likely delivers an average power of about 40 MWe. It covers about 40 km2, so it generates about 1 MWe/km2, indicating an efficiency of solar energy to electrical energy via wind of about 0.5% to 1%. However, land used for wind farms can be used for other purposes as well. But since wind turbines are very noisy, the land near a wind farm is generally not appropriate for humans. Also, the maintenance cost of direct solar and wind installations appears to be very high, as maintenance personnel would have to drive back and forth over many tens of km to service a single 1 GWe facility.
Historically, biofuel from waste products has been used to generate a small portion of American electricity. For instance, paper mills use excess wood chips in this way to generate a few percent of American electricity. More recently, biofuel has meant the growing of plants to provide fuel, for example, deriving ethanol from corn or sugar. For most plants the conversion efficiency of photosynthesis is less than 1%. Right now, at least 25% of America's corn crop goes to manufacture ethanol, and this replaces 1% of our gasoline. This gives an idea of the inefficiency of biofuel as compared to conventional fuel. But it takes nearly as much gasoline to produce ethanol (to drive the tractors, fertilize the land, etc.), so that 1% becomes more like ~ 0.2-0.3%. One result of this is rapidly increasing food prices, causing great hardship in poorer parts of the world. To grow plants for fuel means taking away land that could be used to produce food, lumber, cotton, or which could be conserved. One could describe subsidies for ethaethanol production as taking food from stomachs of the world's poorest in order to add a minute amount of fuel to the cars in the richest parts of the world. This author considers it to be a crime against humanity. There are certainly significant moral issues regarding biofuel. Future research might lead to the production of biofuels from non-food crops and marginal lands, but this remains to be seen. At the end of 2011, two federal ethanol subsidy programs were allowed to expire. However, subsidies still remain for ethanol developed from cellulosic feedstocks, and Department of Energy loan guarantees remain for research and development programs.
Coal for power plants is available on the required scale for quite some time, but unless the CO2 is sequestered, coal burning could have adverse environmental effects. However, sequestration appears to be extremely difficult. One must first economically separate the CO2 from the other much more abundant gases in the waste stream (i.e. nitrogen). If the CO2 is sequestered in gaseous form, there is the real possibility of a catastrophic release, which would be enormously destructive. There are natural precedents. There are several lakes in Africa which are saturated with CO2. One of them, Lake Nyos in Cameroon, abruptly out- gassed in 1986 and released about 1.5 million tons of CO2. About 1700 people and 3500 heads of livestock were killed, basically everyone within 25 kilometers down-wind from the lake. However, as we see from Fig (1), we would have to sequester about 30 billion tons of CO2 every year, assuming it can be done economically at all. There are extremely important safety issues related to sequestration, which have hardly been examined at all. If the CO2 is sequestered as a solid, say calcium carbonate, its weight and volume are much greater than that of the original coal. For every coal train going to a power plant, there would be five or ten times as many going the other way.
How might we achieve the 50 TW needed by mid century to bring the world up to an 'Italian' standard of living? It is difficult to estimate how much energy can be saved by conservation and enhanced efficiency. As a very simple estimate we will use the examples of Sec 3A to estimate that enhanced efficiency and conservation (8) can reduce required power from 50 to 30 TW. This is consistent with a 1% per year decrease in energy intensity (9).
But the world still needs 30 TW. Of this, imagine scaling nuclear power up by a factor of about 15 to about 20 TWth. It would be used to generate all electricity, as well as power trains (electrically) and large ships, which could have their own reactors. Another 6-8 TW would be provided by fossil fuel, mostly in liquid or gaseous form. This would be used for other means of transportation such as cars, buses, small ships and airplanes, as well as for space heating. Until nuclear is fully poised to take over, natural gas could also be used instead of coal to generate electricity. Finally a small amount, perhaps 3-4 TW would be provided by renewable sources, mostly hydroelectricity and biofuel from waste products (not food!), as well as direct solar and wind. One advantage of such an energy budget is that each major element is a proven supplier of energy, i.e. it takes maximum advantage of today's existing infrastructure. This neither ignores the threat of CO2- induced global warming and climate change, nor regards it as an extreme planetary emergency.
It could do a world of good if the APS and AIP advocated a moderate, balanced approach to climate and energy, one that recognizes that global warming is not the only threat to civilization, and perhaps not even the most serious. There are, after all, competing priorities. But instead, American physics organizations have unfortunately taken a one-sided stand on the contentious and extremely complicated issue of climate change. The climate and energy dilemmas are inextricably linked; one cannot talk about climate and ignore energy supply. Yet, these organizations have done just that. Blindly following this advice would end any hope that less-developed parts of the world would have of achieving a western standard of living, and would also greatly reduce living standards in the west. To focus exclusively on climate change (where physicists have limited expertise) and to ignore completely the crucial role of energy for civilization (where physicists are the world's experts) is the height of irresponsibility. A more balanced and even-handed approach is needed. If we do not do so, this APS life-member Fellow fears that we will be on the wrong side of history, and posterity will judge our physics societies harshly.
The goal of world development should be to raise the nations low on Figure 2 upward. But without additional energy sources, preferably carbon-free, this will not only be impossible, but the nations high up will begin to slide down. This is the real threat to civilization.
1. APS statements on climate change, 2007 and 2010.
2. Robert Levine, "Advocacy Threatens Scientific Integrity," Physics & Society 38(1), 6-7 (January 2009).
3. Wallace Manheimer, Letter to the Editor, Physics & Society 38(3), 3 (July 2009).
4. R. Brusca, Daily Princetonian, January 12, 2009, "Professor denies global warming theory"
5. Steven Sherwood, "Science controversies past and present," Physics Today 64(10), 39-44 (October, 2011)
6. Richard C. J. Somerville and Susan Joy Hassol, "Communicating the science of climate change," Physics Today 64(10), 48-53 (October, 2011).
7. M. Hoffert et al., "Advanced Technology Paths to Global Climate Stability: Energy for a Greenhouse Planet," Science 298(5595), 981- 987 (2002).
8. "How American can look within to achieve energy security and reduce global warming", APS study panel, Burton Richter, Chair, September 2008
10. Y. Chang, "Advanced Fast Reactor: A Next-Generation Nuclear Energy Concept," Physics & Society 31(2), 3-6 (April, 2002).
11. R. Hargraves and R. Moir, "Liquid Fuel Nuclear Reactors," Physics and Society 40(1), 6-10 (January, 2011).
12. W. Manheimer, "The case for Fission-Suppressed Hybrid Fusion," Physics & Society 40(2), 10-13 (April, 2011).
13. W. Manheiemr (name misspelled), "Can fusion and fission breeding help civilization survive?" J. Fusion Energy 25(3/4), 121-139 (2006).
14. Peter Fairley, "Japan Faces Post-Fukushima Power Struggle", IEEE Spectrum, August, 2011.
These contributions have not been peer-refereed. They represent solely the view(s) of the author(s) and not necessarily the view of APS.