Renewable Energy Sprawl

A new California law mandate that one-third of the state’s electricity come from “renewable” sources by 2020.  What will this mean in practice?  Robert Bryce explored some of the numbers in an NYT op-ed last week.

The state’s peak electricity demand is about 52,000 megawatts. Meeting the one-third target will require (if you oversimplify a bit) about 17,000 megawatts of renewable energy capacity. Let’s assume that California will get half of that capacity from solar and half from wind. Most of its large-scale solar electricity production will presumably come from projects like the $2 billion Ivanpah solar plant, which is now under construction in the Mojave Desert in southern California. When completed, Ivanpah, which aims to provide 370 megawatts of solar generation capacity, will cover 3,600 acres — about five and a half square miles.

The math is simple: to have 8,500 megawatts of solar capacity, California would need at least 23 projects the size of Ivanpah, covering about 129 square miles, an area more than five times as large as Manhattan. While there’s plenty of land in the Mojave, projects as big as Ivanpah raise environmental concerns. In April, the federal Bureau of Land Management ordered a halt to construction on part of the facility out of concern for the desert tortoise, which is protected under the Endangered Species Act.

Wind energy projects require even more land. The Roscoe wind farm in Texas, which has a capacity of 781.5 megawatts, covers about 154 square miles. Again, the math is straightforward: to have 8,500 megawatts of wind generation capacity, California would likely need to set aside an area equivalent to more than 70 Manhattans. Apart from the impact on the environment itself, few if any people could live on the land because of the noise (and the infrasound, which is inaudible to most humans but potentially harmful) produced by the turbines.

In short, while wind and solar power result in lower greenhouse gas emissions, they require large amounts of land — and that’s not even including the need for transmission lines, or the energy and material requirements of facility construction. In the case of wind turbines, it takes approximately 50 tons of steel to build a single megawatt of capacity. Yet a single megawatt of gas turbine capacity can be built with less than one-quarter ton.

Renewable energy sources have their place, but they should not be oversold. Wind and solar may reduce greenhouse gas emissions, but at the expense of other environmental impacts — impacts that should also be considered.