Modifying natural gas generation to produce lime to reverse climate change

Could we cure climate change? Geoengineering researcher Tim Kruger wants to try. He shares one promising possibility: using natural gas to generate electricity in a way that takes carbon dioxide out of the air. Learn more — both the potential and the risks — about this controversial field that seeks creative, deliberate and large-scale intervention to stop the already catastrophic consequences of our warming planet.

The Origen Power Process feeds natural gas into a fuel cell. About half the chemical energy is converted into electricity, and the remainder into heat, which is used to break down limestone into lime and carbon dioxide.

All of the carbon dioxide generated, both from the fuel cell and from the lime kiln, is pure, and that’s really important, because it means you can either use that carbon dioxide or you can store it away deep underground at low cost. And then the lime that you produce can be used in industrial processes, and in being used, it scrubs CO2 out of the air. Overall, the process is carbon negative. It removes carbon dioxide from the air.

If you normally generate electricity from natural gas, you emit about 400 grams of CO2 into the air for every kilowatt-hour. With this process, that figure is minus 600. At the moment, power generation is responsible for about a quarter of all carbon dioxide emissions. Hypothetically, if you replaced all power generation with this process, then you would not only eliminate all of the emissions from power generation but you would start removing emissions from other sectors as well, potentially cutting 60 percent of overall carbon emissions.

You could even use the lime to add it directly to seawater to counteract ocean acidification, one of the other issues that is caused by CO2 in the atmosphere. In fact, you get more bang for your buck. You absorb about twice as much carbon dioxide when you add it to seawater as when you use it industrially.

The process generates four products – electricity, lime, pure carbon dioxide and the ability to remove carbon dioxide from the atmosphere. A detailed techno-economic assessment of the process published in the journal Applied Energy (Hanak et al) indicates that if the electricity and the lime are sold at wholesale market prices, then the costs are covered without a carbon price – even as it removes carbon dioxide from the air.

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