crop fields

Solar and wind farms are spreading rapidly around the world. Many economists believe that solar power has crossed the threshold where it is generally cheaper than other ways to make electricity and will become the dominant energy source in the next couple of decades. As a result, both solar and wind farms are gobbling up more and more land around the world. Estimates are that they will take up around 30,000 square miles by mid-century.

One concern is whether we are entering an era of trading food for energy. Land conflicts seem inevitable since solar power operates best in unshaded areas with gentle winds and moderate temperatures, which are the same conditions favored by many crops.

China is installing more solar farms than the rest of the world combined. Many of these are in the Gobi Desert, where there is no competing need for the land. But some are in eastern China, in densely populated grain-growing areas.

There are a number of strategies that reduce the impact of solar farms on land use. One approach is to put them on old industrial or brownfield sites that are otherwise unusable. Another is floatovoltaics: putting solar panels on the surface of lakes and reservoirs. And then there is agrivoltaics, where solar panels are installed above crop fields or where livestock graze between or even beneath solar arrays. China has more than 500 agrivoltaic projects that incorporate crops, livestock, aquafarming, greenhouses, and even tea plantations.

Green energy has both environmental and economic benefits to offer, but it must conserve nature and not excessively grab land needed for people, wildlife, and ecosystems.

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‘Green Grab’: Solar and Wind Boom Sparks Conflicts on Land Use

Photo, posted May 25, 2011, courtesy of Michael Mees via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

According to a new study by Cardiff University in the UK, Britain could achieve nearly half of the carbon removal needed to meet its climate goals by adding basalt rock dust to crop fields. The process is known as enhanced weathering and has been the subject of ongoing research in the U.S. at Cornell University and the University of California, as well as in the UK, Canada, and Australia.

Adding rock dust to agricultural lands speeds up the chemical reactions that lock up carbon in soil. Basalt contains magnesium, calcium, and silica, among other components. When basalt is pulverized and applied to soils, magnesium and calcium are released and dissolve in water as it moves through the soil. The minerals in the soil react with the water, and the carbon that would otherwise end up in the atmosphere instead forms bicarbonates, which can hang around in water for thousands of years. It can also eventually make its way to the oceans where it precipitates out as limestone and can stay on the seafloor for millions of years.

Basalt is a waste stream byproduct of mining and manufacturing and is found all over the world. Mining waste is the largest waste stream in the world, so there is no shortage.

According to the U.N. Intergovernmental Panel on Climate Change, applying rock dust to agricultural lands on a global basis could theoretically remove 2 to 4 billion tons of carbon dioxide from the air each year, which is between 34-68% of the global greenhouse gas emissions produced by agriculture annually.

The added rock dust would in fact be good for the soil and for crops. Whether the economics of producing and transporting it make sense remains to be determined.

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Adding Rock Dust to Farmland Could Get UK Almost Halfway to Its Carbon Removal Goal

Photo, posted April 24, 2011, courtesy of the State of Israel via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The green grab for land

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Rock Dust And Carbon | Earth Wise

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