In this webpage I address the issue of Green versus Grey or Blue Hydrogen. The process of making hydrogen using electricity with water does not produce any carbon. Alternatively, the process of using a Steam Methane Reactor and making hydrogen from natural gas — CH4 — will produce carbon when the Hydrogen is extracted. Most of the writing on hydrogen presumes that the cost of hydrogen from an SMR has a much lower cost than from an electrolyzer. This page investigates how you can compute the cost of an SMR with alternative natural gas prices and compares the cost of the SMR with the cost of an electrolyzer that may take advantage of very low cost electricity when the prices are very low or produce hydrogen in proximity of a solar and/or a wind project.