Although renewable energy is a more sustainable energy choice than nonrenewable energy, using any form of energy has an impact on the environment. Biomass, for instance, is a renewable resource only if it is used sustainably. Overharvesting wood leads to deforestation and degradation of the land, as we saw in the description of Haiti in Chapter 3. Wind turbines can kill birds and bats, and hydroelectric turbines kill millions of fish. Manufacturing photovoltaic solar panels requires heavy metals and a great deal of water. Because all energy choices have environmental consequences, minimizing energy use through conservation and efficiency is the best approach to energy use. After we achieve that, we must make energy choices wisely, depending on a variety of environmental, economic, and convenience factors.

Learning Objectives

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After reading this module, you should be able to

Each of the renewable energy resources we have discussed in this chapter has unique advantages. None of these resources, however, is a perfect solution to our energy needs. TABLE 40.1 lists some of the advantages and limitations of each. In short, no single energy resource that we are currently aware of can replace nonrenewable energy resources in a way that is completely renewable, nonpolluting, and free of impacts on the environment. A sustainable energy strategy, therefore, must combine energy efficiency, energy conservation, and the development of renewable and nonrenewable energy resources, taking into account the costs, benefits, and limitations of each. Convenience and reliability are also important factors. Finally, logistical considerations, such as where an energy source is located and how we transport the energy from that source to users, are also important. This is particularly important with the generation of electricity from renewable sources in remote regions, which requires an electrical transmission grid to get it to users.

Energy expert Amory Lovins suggests that innovation and technological advances, not the depletion of a resource, have provided the driving force for moving from one energy technology to the next. Extending this concept to the present, one can argue that we will develop new energy technologies before we run out of the fuels on which we currently depend.

Despite their tremendous potential, however, renewable energy resources are unlikely to replace fossil fuels completely in the immediate future unless nations commit to supporting their development and use through direct funding and financial incentives such as tax cuts and consumer rebates. In fact, the U.S. Department of Energy predicts that fossil fuel consumption will continue to increase in the United States well into the middle of the twenty-first century. In spite of their extremely rapid growth, wind and solar energy still account for far less than 1 percent of all the energy produced in the United States. Government funding or other sources of capital are needed to support research to overcome the current limitations of many renewable energy resources. One limitation that is already evident relates to the transmission of renewable electricity over the electrical distribution network. Other limitations to consider are energy cost and storage.

Improving the Electrical Grid

An increased reliance on renewable energy means that energy will be obtained in many locations and will need to be delivered to other locations. Delivery can be particularly problematic when electricity for an urban area is generated at a remote location. The electrical distribution system—the grid that we described in Chapter 12—was not originally designed for this purpose. So in addition to investing in new energy sources, the United States will have to upgrade its existing electrical infrastructure—its power plants, storage capacity, and distribution networks. Approximately 40 percent of the energy used in the United States is used to generate electricity. The U.S. electricity distribution system is outdated and subject to overloads and outages, which cost the U.S. economy over $100 billion per year. There are regions of the country that cannot supply enough generating capacity to meet local needs, while in other locations the electrical infrastructure cannot accommodate all the electricity that is generated. Furthermore, the current system requires that electricity be moved long distances from power plants to consumers. Approximately 5 to 10 percent of the electricity generated is lost as it is transported along electrical transmission lines, and the greater the distance, the more that is lost. While the storage capacity of batteries improves each year, batteries are not a sustainable solution for this problem of energy loss. Many people are focusing their attention on improving the electrical grid to make it as efficient as possible at moving electricity from one location to another, thereby reducing the need for storage capacity.

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An energy economy based on nondepletable energy sources requires reliable electricity storage and affordable—or at least effective and efficient—distribution networks. U.S. energy scientists maintain that because we currently do not have a cost-effective, reliable means of storing energy, we should not depend on intermittent sources such as wind and solar energy for more than about 20 percent of our total electricity production since it could lead to risky instability in the grid.

One solution currently in development may be the smart grid, an efficient, self-regulating electricity distribution network that accepts any source of electricity and distributes it automatically to end users. A smart grid uses computer programs and the Internet to tell electricity generators when electricity is needed and electricity users when there is excess capacity on the grid. In this way, it coordinates energy use with energy availability. In late 2009, President Obama announced a plan to invest $3.4 billion in smart grid technology. Since that time, industry contributions have brought the total investment to almost $8 billion, which has been used to fund roughly 100 smart grid projects around the country.

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How does a smart grid work? FIGURE 40.1 shows one example. With “smart” appliances plugged into a smart grid, at bedtime a consumer could set an appliance such as a dishwasher to operate before he wakes up the following morning. A computer on the dishwasher would be programmed to run it anytime between midnight and 5:00 AM, depending on when there is a surplus of electricity. The dishwasher’s computer would query the smart grid and determine the optimal time, in terms of electricity availability, to turn on the appliance. The smart grid could also help manage electricity demand so that peak loads do not become too great. We cannot control the timing of all electricity demand, but by improving consumer awareness of electricity abundance and shortages, using smart appliances, and setting variable pricing for electricity, we can make electricity use much more regular, and thus more sustainable.

Our current electrical infrastructure relies on a system of large energy producers—regional electricity generation plants. When one plant goes off-line or shuts down, the reduction in available generating capacity puts greater demands on the rest of the system. Some energy experts maintain that a better system would consist of a large number of small-scale electricity generation “parks” that rely on a mix of fossil fuel and renewable energy sources. These experts maintain that a system of decentralized energy parks would be the least expensive and most reliable electrical infrastructure to meet our future needs. Small, local energy parks would save money and energy by transporting electricity a shorter distance. Such decentralized generators would also be less likely to suffer breakdowns or sabotage. Since each small energy park might serve only a few thousand people, widespread outages would be much less likely.

Addressing Energy Cost and Storage

The major impediments to widespread use of wind, solar, and tidal energy—the forms of renewable energy with the least environmental impact—are cost and the limitations of energy storage technology. Fortunately, the cost of renewable energy has been falling. For example, in some markets wind energy is now cost-competitive with natural gas and coal. Throughout this book we have seen that the efficiency of production improves with technological advances and experience. In general, as we produce more of something, and get experience from making it, we learn to produce it less expensively. Production processes become dramatically more efficient, more companies enter the market, and developing new technologies has a clear payoff. For the consumer, this technological advancement also has the benefit of lowering prices: For electricity generation from solar, wind, and natural gas, we have seen that costs tend to decline in a fairly regular way as installed capacity grows.

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What are the implications of this relationship between experience and efficiency? In general, any technology that has been in widespread use has an advantage over a newer technology because it is familiar and because the less expensive something is, the more people will buy it, leading to further reductions in its price. State and federal subsidies and tax incentives also help to lower the price of a technology. Tax credits and rebates have been instrumental in reducing the cost of solar and wind energy systems for consumers.

Similarly, in time, researchers will develop solutions to the problem of creating efficient energy storage systems, which might reduce the need to transport electricity over long distances. One very simple and effective approach is by using the excess capacity of off-peak hours to pump water uphill to a reservoir. Then, during hours of peak demand, operators can release the water through a turbine to generate the necessary electricity— cleanly and efficiently. Research into battery technology and hydrogen fuel cell technology continues.

Progress on these and other technologies may accelerate with government intervention, taxes on industries that emit carbon dioxide, or a market in which consumers are willing to pay more for technologies with minimal environmental impacts. In the immediate future, we are more likely to move toward a sustainable energy mix if nonrenewable energy becomes more expensive. Consumers have shown more willingness to convert in large numbers to renewable energy sources, or to engage in further energy conservation, when fossil fuel prices increase. We have already seen instances of this shift in behavior. In 2008, energy conservation increased when oil prices rose rapidly to almost $150 per barrel and gasoline in most of the United States cost more than $4 per gallon. People used public transportation more often, drove more fuel-efficient vehicles, and carpooled more than they did before the price spike.

Other ways to spur conservation are initiatives that regulate the energy mix itself—for example, by encouraging that a certain fraction of electricity be generated using renewable energy sources. One such initiative is the Regional Greenhouse Gas Initiative (RGGI), whereby nine eastern states have committed to reducing greenhouse gas emissions from electricity generation plants in this decade.