MATERIAL MATTERS Ten terawatts plus 14 terawatts does not would need to store it so that much less some people in my home town of add up to even half of the 60 terawatts we than 1%escapes from the ground every Houston,where the favorite unit of ener- will eventually need.Of course,we do not year.We could certainly build such stor- gy is the barrel of oil.By saying "solar currently have the technology to build a age facilities in special locations for small energy,we show that we know nothing fleet of nuclear fission breeder reactors- amounts of CO2,but to solve the problem about how big the energy industry is,or let alone a solar or geothermal plant-that for the planet,we would need to build what the"real"energy people are doing. could produce that amount of energy them all over the world and be able to Solar is not now a major player in cheaply.I believe that if we do not find a verify that they will safely store tens of worldwide energy.To those people with way to build such power plants over the gigatons of carbon per year,and do this wry smiles,however,I would like to next decade,or at most two,this 21st cen- year after year.There is no known way to point out that if they like nuclear reactors tury is going to be very unpleasant. do this.Putting CO2 in the ground does as a big-time,big-boy energy solution, not generate any money;instead,it is they should be impressed by a nuclear Finding Alternatives to Oil more like taking money and throwing it reactor that has been going strong for bil- Where are we going to find new energy? down a hole.I have yet to hear a com- lions of years.Without doing anything The list of possible sources will not pro- pelling business case for sequestration. we enjoy the effect of 165,000 terawatts of duce enough of an energy impact.True, power hitting the earth's disk every early on we could achieve some progress Solar Solutions moment of every day.This vast nuclear with conservation and efficiency.In the I do not believe that our energy prob- reactor has gone through over 4 billion developed world,with its top billion peo- lems can be solved through the burning years of shake-down trials,and it is prob- ple,it is possible that we could effect sub- of fossil fuels.Yet,these fuels currently ably going to continue providing stable stantial energy savings.In the undevel- represent our primary energy resources, performance for at least another couple oped world,however,conservation is the only ones we know how to use to our of billion years.We are bathed in energy. meaningless,because so little energy is economic advantage.The energy sources The truth is that there is plenty of ener- used.Even with high efficiency,then,we that could genuinely respond to our gy hitting the surface of the earth.Nate are still going to need vast new energy future needs are all basically from Lewis of the California Institute of Tech- sources.Hydroelectric,as I mentioned,is nuclear sources,either human-made nology likes to demonstrate that we could mostly tapped out.Biomass could be very nuclear fission or nuclear fusion reactors, cleanly meet the world's entire energy significant were we not confronted with a or the nuclear reactions resulting from needs,two kilowatts per person for 10 bil- global food and water crisis.Essentially, the spontaneous decay of uranium and lion people,by applying the following ele- we are trying to move from a situation thorium in the rocks of the earth (geo- gant solution (shown in Figure 3).On a where we pull our energy out of the thermal energy).Then there is that great global map,identify six rectangular spaces ground in oil and gas to one where we big hydrogen fusion reactor up in the located in areas of high solar radiation must grow energy crops every year at a sky,the sun.That is where the truly big create 10%efficiency,then collect that very high rate in order to produce just one resources can be found. power,which would be about 20 ter- terawatt.This would require a revolution Yet,the mention of "solar energy"in awatts of electrical power,the equivalent in agriculture at a time when we are strug- any kind of conversation about world of 60 terawatts total energy power at a gling just to sustain our current production energy will sometimes elicit a wry smile 30%energy conversion.That would total- levels for food. from certain people-for example,from ly solve humanity's energy problem and There has been a lot of talk about the hydrogen economy,which I believe is U despite its virtues,likely to remain a dis- traction from the real,practical solutions to our energy needs.Hydrogen is not a basic energy source.Rather,hydrogen is a way of storing energy and moving it from here to there.Unfortunately,it does not do either of these tasks very well.For NORTH these tasks,electricity is a much better AMERICA answer.Electrical power transmission is ◇ a superb way to move energy from one place to another,and at least on a small scale,electrical power can be stored. The biggest resources right now are in fossil fuels-oil,gas,and coal.We cer- SOUTH AMERICA tainly have enough coal for another five decades or so,if we expand production But we cannot simply burn all that coal and assume that the CO2 problem is going to go away,or that we can ignore it,or get around it.The only way now imagined to deal with the enormity of this issue is sequestration,finding places where CO,can be securely stored.Given Figure 3.Solar cell land area requirements in which the six boxes(100 km on a side),located in that the average lifetime of CO2 in the areas of high solar radiation,can each provide 3.3 terawatts of electrical power to a total of-20 atmosphere is greater than 100 years,we terawatts of electrical power.Courtesy of Nate Lewis of the Califomia Institute of Technology. MRS BULLETIN·VOLUME30·JUWE20O5 415MATERIAL MATTERS MRS BULLETIN • VOLUME 30 • JUNE 2005 415 Ten terawatts plus 14 terawatts does not add up to even half of the 60 terawatts we will eventually need. Of course, we do not currently have the technology to build a fleet of nuclear fission breeder reactors— let alone a solar or geothermal plant—that could produce that amount of energy cheaply. I believe that if we do not find a way to build such power plants over the next decade, or at most two, this 21st cen￾tury is going to be very unpleasant. Finding Alternatives to Oil Where are we going to find new energy? The list of possible sources will not pro￾duce enough of an energy impact. True, early on we could achieve some progress with conservation and efficiency. In the developed world, with its top billion peo￾ple, it is possible that we could effect sub￾stantial energy savings. In the undevel￾oped world, however, conservation is meaningless, because so little energy is used. Even with high efficiency, then, we are still going to need vast new energy sources. Hydroelectric, as I mentioned, is mostly tapped out. Biomass could be very significant were we not confronted with a global food and water crisis. Essentially, we are trying to move from a situation where we pull our energy out of the ground in oil and gas to one where we must grow energy crops every year at a very high rate in order to produce just one terawatt. This would require a revolution in agriculture at a time when we are strug￾gling just to sustain our current production levels for food. There has been a lot of talk about the hydrogen economy, which I believe is, despite its virtues, likely to remain a dis￾traction from the real, practical solutions to our energy needs. Hydrogen is not a basic energy source. Rather, hydrogen is a way of storing energy and moving it from here to there. Unfortunately, it does not do either of these tasks very well. For these tasks, electricity is a much better answer. Electrical power transmission is a superb way to move energy from one place to another, and at least on a small scale, electrical power can be stored. The biggest resources right now are in fossil fuels—oil, gas, and coal. We cer￾tainly have enough coal for another five decades or so, if we expand production. But we cannot simply burn all that coal and assume that the CO2 problem is going to go away, or that we can ignore it, or get around it. The only way now imagined to deal with the enormity of this issue is sequestration, finding places where CO2 can be securely stored. Given that the average lifetime of CO2 in the atmosphere is greater than 100 years, we would need to store it so that much less than 1% escapes from the ground every year. We could certainly build such stor￾age facilities in special locations for small amounts of CO2, but to solve the problem for the planet, we would need to build them all over the world and be able to verify that they will safely store tens of gigatons of carbon per year, and do this year after year. There is no known way to do this. Putting CO2 in the ground does not generate any money; instead, it is more like taking money and throwing it down a hole. I have yet to hear a com￾pelling business case for sequestration. Solar Solutions I do not believe that our energy prob￾lems can be solved through the burning of fossil fuels. Yet, these fuels currently represent our primary energy resources, the only ones we know how to use to our economic advantage. The energy sources that could genuinely respond to our future needs are all basically from nuclear sources, either human-made nuclear fission or nuclear fusion reactors, or the nuclear reactions resulting from the spontaneous decay of uranium and thorium in the rocks of the earth (geo￾thermal energy). Then there is that great big hydrogen fusion reactor up in the sky, the sun. That is where the truly big resources can be found. Yet, the mention of “solar energy” in any kind of conversation about world energy will sometimes elicit a wry smile from certain people—for example, from some people in my home town of Houston, where the favorite unit of ener￾gy is the barrel of oil. By saying “solar energy,” we show that we know nothing about how big the energy industry is, or what the “real” energy people are doing. Solar is not now a major player in worldwide energy. To those people with wry smiles, however, I would like to point out that if they like nuclear reactors as a big-time, big-boy energy solution, they should be impressed by a nuclear reactor that has been going strong for bil￾lions of years. Without doing anything, we enjoy the effect of 165,000 terawatts of power hitting the earth’s disk every moment of every day. This vast nuclear reactor has gone through over 4 billion years of shake-down trials, and it is prob￾ably going to continue providing stable performance for at least another couple of billion years. We are bathed in energy. The truth is that there is plenty of ener￾gy hitting the surface of the earth. Nate Lewis of the California Institute of Tech￾nology likes to demonstrate that we could cleanly meet the world’s entire energy needs, two kilowatts per person for 10 bil￾lion people, by applying the following ele￾gant solution (shown in Figure 3). On a global map, identify six rectangular spaces located in areas of high solar radiation, create 10% efficiency, then collect that power, which would be about 20 ter￾awatts of electrical power, the equivalent of 60 terawatts total energy power at a 30% energy conversion. That would total￾ly solve humanity’s energy problem and ASIA AND RUSSIA AFRICA SOUTH AMERICA NORTH AMERICA EUROPE AUSTRALIA AND OCEANIA Figure 3. Solar cell land area requirements in which the six boxes (100 km on a side), located in areas of high solar radiation, can each provide 3.3 terawatts of electrical power to a total of ~20 terawatts of electrical power. Courtesy of Nate Lewis of the California Institute of Technology