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Anyone for Negative-Emissions Hydrogen?


The IPCC has assigned a critical role to negative-CO2-emissions energy in meeting energy and climate goals by the end of the century, with biomass energy plus carbon capture and storage (BECCS) prominently featured. We estimate that methods of combining saline water electrolysis with mineral weathering powered by any source of non-fossil fuel-derived electricity could, on average, increase energy generation and CO2 removal by >50 times relative to BECCS, at equivalent or lower cost. This electrogeochemistry avoids the need to produce and store concentrated CO2, instead converting and sequestering CO2 as already abundant, long-lived forms of ocean alkalinity. Such energy systems could also greatly reduce land and freshwater impacts relative to BECCS, and could also be integrated into conventional energy production to reduce its carbon footprint. Further research is needed to better understand the full range and capacity of the world’s negative-emissions options.

Content Discussion

Bob Meinetz's picture
Bob Meinetz on August 7, 2018

Greg, it would be helpful if you provided energy balance information for the “electrogeochemistry” pictured in your diagram.

Frankly, it’s hard to believe the clean energy required to power your complex process wouldn’t be more efficiently applied by replacing energy generated by fossil fuels, eliminating all the CO2 they would have emitted.

Greg Rau's picture
Greg Rau on August 9, 2018

Bob, happy to send you the published details via Sure you can use renewable energy directly to reduce emissions, but that does not remove legacy CO2 .  If the paleo recod is any guide, at current CO2 levels sealevel will eventually rise by many meters not to mention other climate and ocean chem impacts we are now and will continue to experience under air pCO2 > 300 uatms. The chance to avoid climate impacts via emissions reduction alone has passed and we must now also search for more pro-active ways to manage air CO2 (IPCC 2013). Here's a chance to harness the globe's vast, stranded energy potential in that CO2 removal effort while also producing a valuable, zero-emissions fuel (and while also rebalancing ocean chemistry).  Coupling this with OTEC also allows surface ocean cooling: see Jim Baird's post.