CO2 removal can lower costs of climate protection

Potsdam Institute for Climate Impact Research: Directly removing CO2 from the air has the potential to alter the costs of climate change mitigation. It could allow prolonging greenhouse-gas emissions from sectors like transport that are difficult, thus expensive, to turn away from using fossil fuels. And it may help to constrain the financial burden on future generations, a study now published by the Potsdam Institute for Climate Impact Research (PIK) shows. It focuses on the use of biomass for energy generation, combined with carbon capture and storage (CCS). According to the analysis, carbon dioxide removal could be used under certain requirements to alleviate the most costly components of mitigation, but it would not replace the bulk of actual emissions reductions.

 “Carbon dioxide removal from the atmosphere allows to separate emissions control from the time and location of the actual emissions. This flexibility can be important for climate protection,” says lead-author Elmar Kriegler. “You don’t have to prevent emissions in every factory or truck, but could for instance plant grasses that suck CO2 out of the air to grow – and later get processed in bioenergy plants where the CO2 gets stored underground.“

In economic terms, this flexibility allows to lower costs by compensating for emissions which would be most costly to eliminate. “This means that a phase-out of global emissions by the end of the century - that we would need to hold the 2 degree line adopted by the international community - does not necessarily require to eliminate each and every source of emissions,” says Kriegler. “Decisions whether and how to protect future generations from the risks of climate change have to be made today, but the burden of achieving these targets will increase over time. The costs for future generations can be substantially reduced if carbon dioxide removal technologies become available in the long run.”

The study now published is the first to quantify this. If bioenergy plus CCS is available, aggregate mitigation costs over the 21st century might be halved. In the absence of such a carbon dioxide removal strategy, costs for future generations rise significantly, up to a quadrupling of mitigation costs in the period of 2070 to 2090. The calculation was carried out using a computer simulation of the economic system, energy markets, and climate, covering a range of scenarios.

Options for carbon dioxide removal from the atmosphere include afforestation and chemical approaches like direct air capture of CO2 from the atmosphere or reactions of CO2 with minerals to form carbonates. But the use of biomass for energy generation combined with carbon capture and storage is less costly than chemical options, as long as sufficient biomass feedstock is available, the scientists point out...

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