Evaluating CO2 sources for power-to-gas applications – A case study for Austria

• Information on CO2 penalty and capture costs of several CO2 sources.
• Evaluation of different CO2 sources for power-to-gas in Austria.
• CO2 from bioethanol and biogas upgrading is best suited as input for power-to-gas.
• CO2 demand for power-to-gas can be met in Austria from existing point sources.

The intermittent nature of wind and solar power requires long-term energy storage options such as power-to-gas. This technology utilizes (surplus) electricity from renewable power sources to produce hydrogen in an electrolyzer. The produced hydrogen can be either directly utilized as an energy carrier or combined with CO2 and further converted to methane. This article evaluates different CO2 sources concerning their potential utilization within the power-to-gas energy storage technology with regard to capture costs, specific energy requirement and CO2 penalties. The results of a case study for Austria indicate that there is enough CO2 available from point sources to store all of the electricity produced from fluctuating renewable power sources (wind power plants and photovoltaics) via power-to-gas. Due to low capture costs, low CO2 penalties, biogenic origins, and short distances to wind power plants, biogas upgrading facilities and a bioethanol plant were determined to be the CO2 sources best suited for utilization in novel power-to-gas plants. However, as the total amount of CO2 produced from these facilities is relatively low in Austria, other CO2 sources would also be required. With moderate capture costs and CO2 penalties, power plants and an existing refinery could also provide CO2 for power-to-gas. Although large amounts of CO2 are available from iron, steel, and cement production facilities, these sources are not recommended for CO2 utilization in power-to-gas, as the CO2 penalty is relatively high and the facilities are rarely located near wind power plants in Austria.