NO MATTER HOW THE NATION’S ENERGY PORTFOLIO CHANGES, an increasing share of future needs will be met by technologies now in the research or development stages.
Some will require substantial improvements—or even research breakthroughs—to have a major impact on our energy budget. The following are some of the options.
Although nuclear power plants account for 20% of U.S. electricity generation, no new reactors have come on line since 1996. Designs conceived in the 1990s (so-called Generation III+) may provide significant improvements in economics and safety. Consortia of companies are working with the Nuclear Regulatory Commission to secure federal approval for these types of nuclear power plants, and several utilities recently requested approval of a combined construction and operating license. Generation III+ plants are also under construction in Europe and Asia, with the first scheduled to come on line in 2009 in Finland.
Longer term advances could broaden the desirability and future use of nuclear energy. The U.S. Department of Energy (DOE) has engaged other governments, international and domestic industry, and the research community to develop “Generation IV” systems. The goals of these efforts are to improve the economics, safety, fuel-cycle waste management,
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NO MATTER HOW THE NATION’S ENERGY PORTFOLIO CHANGES, an increasing share of future needs will be met by technologies now in the research or development stages. Some will require substantial improvements—or even research breakthroughs—to have a major impact on our energy budget. The following are some of the options. ADVANCED NUCLEAR FISSION Although nuclear power plants account for 20% of U.S. electricity generation, no new reactors have come on line since 1996. Designs conceived in the 1990s (so-called Generation III+) may provide signiﬁcant improvements in economics and safety. Consortia of companies are working with the Nuclear Regulatory Commission to secure federal approval for these types of nuclear power plants, and several utilities recently requested approval of a combined construction and operating license. Generation III+ plants are also under construction in Europe and Asia, with the ﬁrst scheduled to come on line in 2009 in Finland. Longer term advances could broaden the desirability and future use of nuclear energy. The U.S. Department of Energy (DOE) has engaged other governments, international and domestic industry, and the research community to develop “Generation IV” systems. The goals of these efforts are to improve the economics, safety, fuel-cycle waste management, 24
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and proliferation resistance of nuclear reactors, as certain materials, the energy of incoming light kicks well as widen their applications. DOE is pursuing electrons into motion, creating a current. Sheets of the demonstration of one such design, a very-high- these materials are routinely employed to power temperature reactor, through its Next Generation a host of devices from orbiting satellites to pocket Nuclear Plant program, and the facility is scheduled calculators, and many companies make roof-sized to begin operations by 2021. units for homes and ofﬁce buildings. At the present time, however, the best commercial SOLAR POWER PV systems produce electricity at ﬁve to six times Sunlight is Earth’s most abundant energy source the cost of other generation methods. In addition, and is delivered everywhere free of charge. Yet PV is an intermittent source, meaning that it’s only direct use of solar energy—that is, harnessing light’s available when the sun is shining. Furthermore, energy content immediately rather than indirectly unless PV energy is consumed immediately, it must in fossil fuels or wind power—makes only a small be stored in batteries or by some other method. contribution to humanity’s energy supply. In theory, Adequate and cost-effective storage solutions await it could be much more. In practice, it will require development. One factor favoring PV systems is that considerable scientiﬁc and engineering progress in they produce maximum power close to the time of the two ways of converting the energy of sunlight peak loads, which are driven by air-conditioning. into usable forms. Peak power is much more expensive than average power. With the advent of time-of-day pricing for Photovoltaic (PV) systems exploit the photoelectric power, which is technologically feasible, PV power effect discovered more than a century ago. In would be much closer to being economical. 25
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Sunlight can also be focused and concentrated by recent advances in nanotechnology, applied to the mirrors and the resulting energy employed to heat lithium ion battery, may permit signiﬁcantly more liquids that drive turbines to create electricity—a energy to be stored in a smaller, lighter package. technique called solar thermal generation. Existing systems produce electricity at about twice the cost of A compromise—plug-in hybrid electric vehicles fossil-fuel sources. Engineering advances will reduce (PHEVs)—may secure a signiﬁcant place in the the cost, but solar thermal generation is unlikely to market sooner. PHEVs have conventional gasoline be feasible outside regions such as the southwestern engines as well as batteries that can supply enough United States that receive substantial sunlight over energy to travel 10 to 40 miles, depending on the long time periods. kind of batteries used. They run on electric power until the batteries are discharged, then switch to gasoline for additional range. As of January 2008, no ELECTRIC VEHICLES PHEVs were in production. But several major motor Many new vehicle technologies have the goal of companies—including Toyota, General Motors, and steering automobiles away from a dependence on Ford—have plans to introduce PHEVs within the next fossil fuels. One vision is an all-electric vehicle (EV) few years. that uses no gasoline or diesel fuel and does not emit any CO2. But affordable and reliable EVs will require EV and PHEV batteries are recharged by plugging advances in energy storage. At present, batteries that them into an electricity source while the vehicle store enough electricity to give a vehicle acceptable is parked. This provides the immediate beneﬁt of driving range are expensive, large, and heavy. Yet shifting some transportation energy demand from technology may provide new options. For example, onboard petroleum-based fuels to the electrical grid. However, CO2 emissions would not decline proportionally because about half of the electricity used to recharge the vehicle’s batteries is produced at coal-based plants. WIND ENERGY This renewable technology, already widely deployed in 36 states and producing almost 1% of America’s electricity, uses the wind-induced motion of huge multiblade rotors—sweeping circles in the air 100 yards in diameter—to drive emission-free turbines. Tesla Motors’ Roadster EV has enough battery But like solar energy, the source is intermittent and power to travel 220 miles. That’s still not currently lacks an economically practical way to enough for a long road trip, but it represents store its energy output. In addition, the huge wind signiﬁcant improvement. 26
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turbines (sometimes grouped into “wind farms” They also substantially increase the cost of the containing hundreds of turbines) can prompt electricity produced. complaints on aesthetic grounds from communities whose sight lines are altered. Current designs can Once CO2 has been captured, it must be sequestered, also be a hazard to birds and bats. Wind energy’s or permanently stored. Current options focus on potential contribution is large, though, and with such geological formations as oil and gas reservoirs, developments in storage technologies and an unmineable coal seams, and deep saline aquifers, all expanded and upgraded electrical grid, it could of which are geologically sealed and unlikely to allow provide a substantial portion of our electricity, injected CO2 to escape. While these technologies especially in some regions. are very promising, it still must be proven that large quantities of CO2 can be stored effectively underground and monitored for long periods of time. ADVANCED COAL TECHNOLOGIES The methods also must be acceptable to the public In the endeavor to reduce—or even eliminate—the and regulatory agencies. Large-scale ﬁeld trials of emission of CO2 when fossil fuels are burned, coal prototypes of coal-fueled, near-zero-emissions power is a prime target: It accounts for about one-third of plants are needed to test the viability of several of the nation’s CO2 emissions. New technologies focus these new clean coal technologies. on separating, capturing, and safely storing the CO2 before it is discharged from the smokestack. Several FUEL CELLS approaches are possible. One is coal gasiﬁcation, a process in which coal is converted to a gas (called For more than 150 years, scientists syngas) before it is burned, making it easier to have known that when hydrogen separate the CO2 as a relatively pure gas before power and oxygen combine to form water is generated. Such Integrated Gasiﬁcation Combined (H2O), the chemical reaction releases Cycle, or IGCC, plants are projected to be up to 48% electrical energy. (It’s exactly the efﬁcient, a signiﬁcant improvement over current coal- reverse of electrolysis, in which power plants, which are about 38% efﬁcient. running a current through water separates H2O into its constituent Another option is to burn coal in oxygen instead elements.) Devices that use a of air (as is currently done), to reduce the amount controlled combination of the two gases to generate of ﬂue gas—essentially exhaust—that must be current are called fuel cells. This developing processed to isolate CO2. These techniques show technology underlies the vision of a nationwide promise but require more research and development. “hydrogen economy,” in which the only exhaust 27
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from fuel-cell-powered vehicles would be water development and successful introduction into vapor, and America would drastically reduce its the marketplace. And hydrogen-fuel-cell cars are dependence on foreign fuel supplies. receiving considerable attention in the press. Some car manufacturers, including General Motors and There are several signiﬁcant obstacles to achieving Honda, are putting a very limited number of these that vision. Present fuel cells are too expensive and vehicles on the road. There are hydrogen fueling unreliable for the mass market. And hydrogen is very stations in about 16 states, the greatest number being difﬁcult to store and transport in a vehicle unless it is in California. Most of these, though, are small, private compressed to thousands of pounds per square inch facilities intended to support a few experimental (psi). Automotive companies are using containers vehicles. It will take decades of research and in their demo vehicles that can store hydrogen at development, as well as changes in the energy 5,000 to 10,000 psi, but a cost-effective and safe infrastructure, before a hydrogen economy on a distribution system would have to be put in place broad scale can be achieved. before these vehicles could become widely available. ALTERNATIVES TO Furthermore, hydrogen (like electricity) is not a CONVENTIONAL OIL primary source of energy but rather an energy carrier. There are several “unconventional” petroleum There are no natural reservoirs of pure hydrogen; it sources, materials from which oil can be extracted— must be extracted from compounds such as natural at a cost. Resources are abundant and could greatly gas or water. And the processes for separating it from impact the U.S. oil supply in the future. The three these principal sources pose their own challenges. largest are oil shale (rock that releases petroleum-like When natural gas (basically methane, a lightweight liquids when heated in a special chemical process); molecule made of carbon and hydrogen) is exposed tar sands (heavy, thick, black oil mixed with sand, to steam under high temperatures in the presence of clay, and water); and heavy crude oil (thicker and a catalyst, it frees the hydrogen. However, the process slower ﬂowing than conventional oil). itself also produces substantial amounts of CO2. Widespread use would require a carbon sequestration The most extensive deposits of all three are in North scheme. And, of course, hydrogen can be extracted and South America. A region covering parts of from water by electrolysis. But that takes a lot of Colorado, Utah, and Wyoming contains oil shale electric power. So unless the electricity is generated by nuclear or renewable sources, the environmental advantage of hydrogen is substantially negated. The federal government, particularly the U.S. Department of Energy, is conducting signiﬁcant research on fuel cells to accelerate their 28
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totaling about three times the proven oil reserves doubtful. Typically, those oils are of Saudi Arabia. About two-thirds of the world’s already expensive compared to supply of tar sands (estimated at 5 trillion barrels, fossil-fuel sources, and there does though not all of it is recoverable) is found in not appear to be a way to bring the Canada and Venezuela. Venezuela also has the cost down. largest known reserves of heavy crude oil, estimated at 235 billion barrels. As mentioned previously, corn- based ethanol is already offsetting However, extracting these resources is much more a small amount of fossil-fuel use in costly, energy intensive, and environmentally vehicles. However, many experts damaging than drilling for conventional oil. The believe that ethanol-based biofuels processes by which we mine and reﬁne oil shale and will not provide much beneﬁt tar sands to produce usable oil, for example, involve until the conversion technology is fully developed signiﬁcant disturbance of the land, extensive use to use cellulose (as found in trees and grasses) for of water (a particular concern in dry regions where the raw material instead of corn or sugar cane. In oil shale is often found), and potential emissions of fact, the Energy Independence and Security Act of pollutants to the air and groundwater. In addition, 2007 stipulates that by 2022 the United States must more energy goes into these processes than into produce 21 billion gallons of advanced biofuels, such extracting and reﬁning conventional oil, and more as cellulosic ethanol. Research is under way in this CO2 is emitted. But as conventional oil costs rise, ﬁeld, which could provide a ubiquitous sustainable more attention is being focused on alternative sources resource and perhaps take advantage of the existing and on overcoming the challenges associated with nationwide infrastructure created for petroleum-based their use. Canada already produces more than a fuel distribution. million barrels per day of oil from tar sands, and some companies are interested in pursuing oil shale Even with this increased focus on biofuels, however, in the United States, probably using below-ground it is uncertain how much projected gasoline techniques to extract the oil without mining the shale. consumption can be replaced in the next few decades. Furthermore, biofuels contain carbon, and although they may burn “cleaner” than oil-derived fuels, they BIOFUELS would not completely eliminate CO2 emissions. Fuel derived from plant material, or biofuel, is an appealing renewable alternative to fossil fuels. It is Many of these technologies will likely contribute in uncertain, though, whether biofuels are ultimately some way to America’s energy sources in the 21st viable in the absence of subsidies. In particular, the century. But it is impossible to predict how much prospects for “biodiesel” fuel—a relatively heavy impact these and other technologies will have on our liquid derived from soybean, vegetable, rapeseed, energy future. or safﬂower oils, among others—are considered 29