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The global potential for converting renewable electricity to negative-CO2-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.

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Fig. 1: Various schemes for electrolytically generating H2 while consuming CO2 and transforming it to dissolved mineral bicarbonate.
Fig. 2: Global energy (H2) generation potential versus global CO2 removal potential for the NE H2 process when powered by each of the electricity sources noted.
Fig. 3: Supply–cost curves of cumulative potential global energy production versus cost of production (in ascending order of cost) for NE H2 and for renewable electricity from the six renewable energy sources listed (Table 1).
Fig. 4: Supply–cost curve of cumulative CO2 removal potential versus cost (in ascending order of cost) for NE H2 employing the six electricity sources listed in Table 1.


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The authors acknowledge (1) the support of Lawrence Livermore National Laboratory and input from R. Aines and S. Carroll (G.H.R.), (2) support by the Office of Naval Research both directly and through the US Naval Research Laboratory (H.D.W.) and (3) funding from the US National Science Foundation (grant no. CBET 1704921 to Z.J.R.). M. MacCracken provided valuable editorial input.

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G.H.R. conceived of and led the project, analysed data and wrote the paper. H.D.W and Z.J.R provided data and helped write the paper.

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Correspondence to Greg H. Rau.

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Rau, G.H., Willauer, H.D. & Ren, Z.J. The global potential for converting renewable electricity to negative-CO2-emissions hydrogen. Nature Clim Change 8, 621–625 (2018).

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