Even among those who accept the reality of climate change and the central role of human-produced CO2 emissions, there is a view that renewable energy is not a viable alternative to energy produced by fossil fuels. Among other things, it is felt to be too expensive, unreliable, inadequate and/or impractical.

However, according to a report published in 2012 by the National Renewable Energy Laboratory, "U.S. Renewable Energy Technical Potentials: A GIS-Based Analysis," the U.S. has the technical potential to produce 212 terawatts or TW using renewable energy technologies. This is an enormous amount of energy production, equaling more than 180 times the total amount of electricity produced in the U.S. in 2011 - about 1.1 TW or 1,153 gigawatts or GW.

Among the available technologies, three - utility-scale photovoltaics, large solar arrays and land-based wind turbines - have the potential to meet many times our current electrical requirements. Other technologies such as rooftop solar panels, offshore wind power, biomass, hydrothermal, geothermal and hydropower also have tremendous productive potential, ranging from 0.4 to 4 TW.

Usefully, the report also estimates the amount of land that would be required by wind and solar technologies, as well as the production potential of each state. By reviewing the report, a state (or community) can estimate its potential to meet all of its electrical power requirements with renewable energy. Idaho, for example, would require only about 0.5 percent of its total land area to meet its electrical energy requirement of about 6 GW.

So, the renewable energy challenge can be seen as largely a land-use challenge, that of assembling enough land to build adequate productive capacity. This is a challenge that would best be met at the state or regional level, where land assembly could be coordinated and allocated most efficiently among communities and residents. For example, while the city of Moscow could meet its electricity requirements with a 500-acre utility-scale photovoltaic project, it would need over 4,000 acres for a wind farm, more than six square miles. For a city the size of Boise, multiply those figures by about nine, and the importance of regional or even multi-state coordination becomes obvious.

In addition, all these technologies vary in their cost. However, according to the U.S. Energy Information Administration, the cost difference between renewable energy projects and comparable conventional projects such as coal, natural gas and nuclear is narrowing. For example, the electricity produced by a wind energy farm is less expensive than all fossil fuel systems except natural gas. And, electricity generated by a utility-scale photovoltaic systems costs only about 17 percent more than that generated by advanced coal plant systems.

There is an emerging opportunity to re-direct investment to support renewable energy development. Of the thousand or so existing coal plants, more than 60 percent were built before 1964 and will soon need to be replaced. This presents us with an excellent opportunity to use money that would have been spent replacing aging coal plants to instead build solar and wind projects on a scale large enough to significantly impact CO2 emissions.

Communities can take actions now to begin to build their local renewable energy production using existing technologies. While they may not become energy self-sufficient, they will become more self-reliant and the world will become more sustainable. In addition, the involvement of more communities in applying these technologies will contribute to their improvement, as well as help clarify the advantages of regional collaboration and integration.

All things considered, the challenge of reducing CO2 emissions should be met with a sense of guarded optimism. Because, unlike just a few years ago, renewable energy technologies are now ready for local deployment at scales that can make a big difference. Such deployment can serve as the foundation for a national transformation.

Edward Jepson is a certified planner and adjunct faculty member at the University of Idaho in bioregional planning and community design.

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