Renewable Energy Certificate (REC)

A renewable energy certificate (REC) is a tradable instrument representing the environmental attributes of one megawatt-hour of electricity generated from a renewable source, issued separately from the physical power. Buyers retire RECs to substantiate renewable-electricity claims, decoupling the attribute from the grid electron. In maritime decarbonization, RECs and equivalent guarantees of origin underpin the renewable-power claims behind shore power and behind electrolytic hydrogen, ammonia, and e-methanol production, where book-and-claim accounting links green electricity to the fuel. The certificate matters because a fuel’s well-to-wake carbon intensity depends on whether its input electricity is genuinely renewable and not double-counted.