Humanity is facing a climate crisis, with our fossil fuel consumption driving an unsustainable increase in global temperatures. While electrification can replace many applications of fossil fuels, the chemicals industry requires carbon neutral or even negative feedstocks, and some transport methods such as air travel mean the energy density of a chemical fuel is still required. In the last 30 years electrochemical CO2 reduction has emerged as an approach to make fuels and chemicals, allowing the potential to remove CO2 from the atmosphere or prevent its release at source. Nature however beat humanity by millenia, using the calvin cycle to turn CO2 into biomass.