The ZECA plant is simple and elegant, recycling nearly all waste products and heat. Coal, water, and lime (calcium oxide) combine in two chemical reactions to produce hydrogen, limestone (calcium carbonate), and waste ash. Hydrogen powers fuel cells, which produce electricity, water, and heat. The water goes back into the coal gasification process, while the heat drives a chemical reaction that separates the limestone into lime and pure CO2. The lime then goes back into the process, and only the CO2 is left. Finally, the CO2 combines with powdered soapstone to produce magnesium carbonate, an inert, stable mineral that can be safely disposed of.