Comparative Technoeconomic Analysis of Renewable Generation of Methane Using Sunlight, Water, and Carbon Dioxide

Thirty-one percent of the primary energy consumed in the United States comes from the burning of natural gas, 70–90% of which is composed of methane (CH₄). Natural gas is recovered from onshore and offshore natural gas and oil wells and from coal beds. Currently, the United States has enough supply of dry natural gas to sustain current consumption for 92 years. Meanwhile, California consumes 2.14 MMcf (43.2 million tons) of natural gas per year, over a quarter of which is used to generate electric power and which provides approximately 40% of the electrical energy in the state. Because an extensive nationwide storage and distribution network already exists for natural gas, the development of renewable CH₄ could enable rapid and widespread distribution of zero-carbon energy services. Thus, for California to meet its renewable portfolio standard, that is, 60% renewable energy for electricity generation by 2030, and to conserve a limited resource, it is imperative to assess how to develop and deploy technologies for renewable generation of CH₄ in the next decade.