Economics and greenhouse gas emissions of solar-thermochemical fuels
Within the EU-funded research project SOLAR-JET,1 the worldwide first “solar” kerosene has been produced. Under the leadership of Bauhaus Luftfahrt, which also acted as project co-ordinator, the economic and ecological potential of the fuel production pathway was investigated.2
A suitable location with a high solar irradiation and the enhancement of the thermochemical energy conversion efficiency were identified to have the largest influence on both economics and environmental footprint of solar-thermochemical kerosene production. Furthermore, expenditures for the construction of the production facility and its operation have a large effect on production costs.
For a facility with a daily production of 1,000 bbl. of solar kerosene, and solely using solar energy and CO2 captured from the atmosphere, production costs of 2.2 € per litre kerosene at specific greenhouse gas emissions of 0.5 kg CO2 equivalents are estimated, corresponding to a reduction of 80 % in emissions, compared to conventional kerosene.
If CO2 is captured from a modern natural gas power plant, production costs may be slightly reduced, however, emissions rise to values higher than that of conventional fuel. If the process efficiency can be further enhanced, and at optimal conditions at the chosen location, production costs of 1.3 € per litre at specific emissions near zero seem achievable.
It could, thus, be shown that solar fuels have a large economic and ecological potential. Further development of the process is performed in the EU-funded follow-up project SUN-to-LIQUID.1
1 The project SOLAR-JET (Solar chemical reactor demonstration and Optimization for Long-term Availability of Renewable JET fuel) receives funding from the European Union’s 7th Framework Programme (FP7/2007–2013) under grant agreement no. 285098 and the project SUN-to-LIQUID (Integrated solar-thermochemical synthesis of liquid hydrocarbon fuels) from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 654408.
2 C. Falter, V. Batteiger, A. Sizmann, “Climate Impact and Economic Feasibility of Solar Thermochemical Jet Fuel Production”, Environmental Science and Technology, 50(1), pp 470-477, 2016
- Energy balance of solar fuel production: The energy balance shows the demand for heat and electricity of the single process steps. The major part of the energy is required for concentration of solar energy and thermochemical conversion.
- Distribution of investment costs and CO2 emissions: a) Construction of the solar concentration facility accounts for the largest share of investment costs. b) Atmospheric CO2 compensates for 80 % of the greenhouse gas emissions that originate mainly from combustion of the solar fuel.