DesertBlog

Solar worse for habitat than coal?

A fascinating new peer-reviewed study of energy development indicates that centralized solar electric generation may destroy more habitat per kilowatt-hour produced than coal, even taking mining into account.

The study, Energy Sprawl or Energy Efficiency: Climate Policy Impacts on Natural Habitat for the United States of America by McDonald, Fargione, Kiesecker, Miller and Powell, sponsored by the Nature Conservancy and published in the Public Library of Science, examined a range of energy sources and delivery modes, from biodiesel and ethanol to nuclear and geothermal.

The authors calculated the land area within the US required to meet our energy consumption levels based on assumptions in current cap and trade laws, then ranked each source of energy by its power output divided by the total land area that energy source would disrupt. The authors refer to this area used as “energy sprawl”: you’ll likely be hearing this useful coinage a lot in years to come.

Unsurprisingly, biofuels have the highest energy sprawl numbers of any of the energy sources studied. Ethanol, biomass-fueled electrical generation and biodiesel combined would require more than 2,500 square kilometers — about 960 mi² — per Terawatt-hour of energy generated per year. Nuclear and geothermal sit at the bottom of the list.

What is more surprising are the relative positions of coal-fired and solar electrical generation. Coal consumes almost 10 square kilometers per TW-hr/year, taking into account the devastating effect of surface mining, slag heap “storage,” and the infrastructure needed to transport and burn the stuff. But concentrating solar would use even more: 15.3 km² per TW-hr/year, and less-efficient photovoltaic generation would take a staggering four times the amount of land to generate the same amount of electricity as coal.

In other words: for every square mile of Appalachian mountain destroyed in coal mining, we’re faced with the prospect of paving somewhere between one-and-a-half and four square miles of desert instead to replace that coal-fired power with industrial solar.

Of course given the CO₂-driven ecological and social catastrophes that loom if we don’t stop burning coal, switching to solar power is imperative. And fortunately — sort of — we already have a staggering amount of land area that is permanently destroyed from a wildlife habitat perspective, that is thus suitable for photovoltaic power generation, and even some concentrating solar. It’s called “cities.”

Least surprising of all, the study found that conserving energy is by far the best choice from a land-use perspective. So turn off that AC.