Can the U.S. Reach 100 Percent Renewable Electricity in 10 Years?

by Paul Gipe, Wind Expert

Washington, D.C., United States [RenewableEnergyWorld.com]

Q: In Al Gore's speech this week in Washington, he said that the U.S. should strive toward getting 100 percent of its electricity from renewable resources in 10 years. Is it realistic to propose a target like that? -- Terry G., Berkeley, California
A:

Terry, that's a very good question, and one that I'm sure a lot of people who heard his speech will be asking. Ten years is certainly an aggressive target, but many experts who consulted with Gore have said that it is achievable. Some experts would say that it is more likely within a 12-20 year time frame, but whatever the case, the point is that the target is theoretically feasible and we should be doing all we can to try to rise to the challenge.

Below is a portion of my speech that I gave to Gore's Solution Summit in January. In the presentation, I outline the possibility of getting one million megawatts from wind in the U.S. — an important part of this 100 percent target that was just proposed by Gore.

From a January 10th 2008 speech to Al Gore's Solution Summit:

To significantly address the United States' contribution to climate change and to prepare for the diminishing supply of liquid fuels and their increasing volatility, the nation needs to embark on a grand effort to install one million megawatts (MW) of wind generating capacity. Anything less will miss the mark.

North Americans have been dabbling around the edges of energy policy. Until recently, few have acknowledged the seriousness of the challenge facing the continent.

The scale of the task is enormous, but eminently doable. Americans have risen to great challenges in the past and we can do so again. Americans built great public work projects to pull ourselves out of the Great Depression. The hydroelectric projects on the Columbia, the Colorado, and the Tennessee rivers are witness to what we can accomplish when we put our minds to it. We rose to the challenge of fascism in WWII. We belatedly granted civil rights to all our citizens in the 1960s and in the modern era we have pushed cigarette smoking to the fringes of society.

Our next great challenge will be the rapid conversion of American electricity supply from fossil fuels to renewable sources of energy, and the conversion of the bulk of personal transportation to electric vehicles. In doing so we can transform society and re-industrialize the continent's heartland.

Here's a simple summary of targets necessary to make the difference needed:

Currently the U.S. consumes ~4,000 terawatt-hours of electricity per year (TWh/yr) That's 4,000 billion kWh/yr. Americans use more electricity per capita than almost anyone else on the planet. Europeans, for the same level of comfort, services, and industrial production, use one-half the per capita consumption of Americans. The U.S., then, can cut its consumption of electricity by at least 50% for the same standard of living as now. Thus, a rational target for U.S. consumption is ~2,000 TWh/yr.

Wind is only one form of renewable energy. To build a truly sustainable supply we will need all forms of renewable energy, not only wind. Nevertheless, we'll only examine the role that wind can play.

Wind generation is variable. At any single wind turbine the wind is not always blowing. However, when a continent-wide network of wind turbines are connected together, wind can provide a significant portion of total generation. Some studies have suggested that 50% of supply can be provided by wind with modest amounts of backup generation.

Wind could then supply 50% of reduced U.S. consumption or ~1,000 TWh/yr. (This is equivalent to ~25% penetration for the business as usual case, that is, without a massive conservation effort.)

Today most wind turbines in North America are installed on the windiest sites possible. These turbines are highly productive. However, as the industry expands, it will be forced to use increasingly less windy sites. Typically, wind turbines on a regional or national scale, like those in Germany, Denmark, or California, produce ~2 TWh/yr for every 1,000 MW of wind capacity installed.

For the wind to generate ~1,000 TWh/yr, we would need to install ~500,000 MW of wind generating capacity across the breadth of the country.

Now, let's turn to the enormous number of passenger-vehicle miles traveled annually in the United States. Their consumption of liquid fossil fuels contribute substantially to America's carbon emissions.

Americans drive ~5,000 billion kilometers per year. To power this fleet with electric vehicles would require a huge new supply of clean electricity. Current electric vehicles can travel ~0.25 km/kWh of electricity supplied. Thus, converting passenger vehicles to electricity will require the generation of ~1,000 TWh/yr. Using the same assumptions as before, this would demand the installation of ~500,000 MW of new wind generating capacity.

To provide 25%-50% of electricity supply with wind and 100% of passenger-vehicle miles traveled with electricity will require the installation of ~1,000,000 MW of wind generating capacity.

Theoretically, it can be done. There's more than ample land area in the U.S. for such a large number of wind turbines. Even with very open spacing (e.g. turbines placed 8 rotor diameters by 10 rotor diameters apart) ~1 million MW would require little more than 3% of the land area of the lower 48 states. And of this land, the wind turbines would only use about 5% for roads and ancillary facilities.

Moreover, the U.S. has the manufacturing capacity to build such a large number of machines within less than two decades.

Every year American manufacturers of heavy trucks churn out ~300,000 vehicles. Each heavy truck is the equivalent of a ½ MW wind turbine. Thus, heavy truck manufacturers alone build the equivalent of ~150,000 MW/yr.

If two-thirds of truck production were diverted to manufacturing wind turbines, the industry could build ~100,000MW/yr. Thus, it is theoretically possible that the American heavy truck industry could provide 1,000,000 MW in about one decade.

Clearly one million MW of wind capacity in the United States alone is an ambitious target, but it's a target worthy of a great nation.
 

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