Macroeconomics

Natural gas

Engineering

Ecology

Biology

Renewable natural gas

Economics

Syngas

Power to gas

Physical chemistry

Paleontology

Biochemical engineering

Waste management

Mechanical engineering

Hydrogen

Fuel gas

Greenhouse gas

Organic chemistry

Renewable energy

Substitute natural gas

Industrial gas

Combustion

Flue gas

Natural (archaeology)

Process engineering

Environmental science

Capital cost

Natural gas prices

Chemistry

Electrode

Gas turbines

Carbon dioxide

Electrolyte

Electrolysis

Production (economics)

Electrical engineering

Applied Energy

The Power-to-Gas strategy has become a mainstream topic for decarbonization and development of renewables and flexibility in energy systems. One of the key arguments for decarbonizing the gas network is to take advantage of existing network infrastructure, gradually transitioning to lower fossil carbon sources of methane from Power-to-Gas. This work proposes the techno-economic investigation of an integrated system considering an advanced CO2 capture process, in terms of solvent and process configuration, to treat about 10% of a cement plant’s flue gas and convert the captured CO2 into synthetic natural gas using renewable hydrogen generated from a large-scale wind powered electrolyzer. An optimized heat recovery system is proposed, drastically decreasing the external hot utility demand of the CO2 capture unit. In addition, it leads to the production of complementary electricity (about 1.06 MW), reducing thus also the electrical demand of the integrated process. The synthetic natural gas produced has a composition (CH4 92.9 mol.%, CO2 3.7 mol.%, and H2 3.4 mol.%) and a Wobbe index (46.72 MJ/m3), corresponding to specification for gas grid injection at 50 bar in Germany. With an overall system efficiency of 72.6%, the process produces 0.40 ton synthetic natural gas per ton of captured CO2. The cost of the synthetic natural gas produced is higher when compared to the present natural gas market price, but cost reductions and possible commercial use of coproducts like oxygen, represent a likely alternative. Costs are mainly driven by high capital investments (the electrolyzer), and the price of renewable electricity, which is expected to decrease in the coming years.

Production of synthetic natural gas from industrial carbon dioxide