(621c) Aviation Fuel from Solar Energy: A Spain Supply Chain Network.

The aviation industry is responsible for approximately 2% of total anthropogenic greenhouse gas emissions. Consuming 350 Mt of jet fuel per year, the sector releases around 910 Mt of life cycle CO₂ (IATA, 2019). Having an expected four to six fold growth in consumption by 2050, increased attention has been placed to reduce its carbon footprint (Sustainable Aviation, 2020; Transport & Environment, 2018). In this context, solar energy is the most abundant type of energy available to mankind and has the potential to be transformed into liquid fuels (Nocera, 2017). This presents an opportunity for the large-scale production of liquid fuels from solar energy to cover future demand at relatively low CO₂ emissions. However, realising such a pathway implies the deployment of a range of technologies at each step along the whole production process. As a result, the identification of the most sustainable production route still remains a challenge. Aiming to address this problem and inform decision making, we present a model-based approach to identify optimal routes for the production of jet fuel from a cost and CO₂ emissions perspective.

The model presented relies on an MILP superstructure that accounts for resources and technologies whose availability is constrained to a particular region. The routes considered for the production of jet fuel include the Fischer-Tropsch (FT) (Klerk, 2011) and Methanol to Fuels (MtF) (Tabak & Yurchak, 1990) processes. The optimization of the network provides the temporal and spatial interconnectivity design of imported resources and intermidiate/final products along with the material transportation network and related process technologies. The methodology presented is applied using Spain as the location of the case study, adjusting the regional demand and solar energy availability according to daily and seasonal time scales.

The results of the network, which could vary for a different location, show current production costs per kg of liquid fuel from 3.5 € (MtF) to 4.4 € (FT) using solar radiation as unique source of energy. From these, ≈90% come from capital costs of solar PV and elecrolysis technologies. These costs are nearly ten-fold current production costs from fossil fuels estimated at 0.47 €/kg fuel. In terms of emissions, both MtF and FT processes cut CO₂ life cycle emissions by ≈25% compared to their fossil-based counterpart, releasing 2.5-2.7 kg CO₂eq/kg liquid fuel on a cradle-to-grave basis. In this case, the CO₂ embodied in the installation of solar PV, and particularly solar panels, is the main contributor to the impact. Projections toward 2050 show potential cost reductions up to 2.5 € for MtF and 3.0 € for FT with lifecycle emissions below 1.00 kg CO₂eq/kg liquid fuel. The performance of the network is also analyzed at different conditions and fuel demand, including the import of electricity and varying costs for electricity and hydrogen storage. Ultimately, the use of solar energy to supply jet fuel would represent an increase of costs in a flying ticket by two- to three-fold for a competitive route at distances ~1,000 miles (London-Madrid).

References

IATA. (2019). IATA Fact Sheet - June 2020. https://www.eesi.org/papers/view/fact-sheet-the-growth-in-greenhouse-gas...

Klerk, A. De. (2011). Fischer-Tropsch fuels refinery design. In Energy and Environmental Science (Vol. 4, Issue 4, pp. 1177–1205). https://doi.org/10.1039/c0ee00692k

Nocera, D. G. (2017). Solar fuels and solar chemicals industry. In Accounts of Chemical Research (Vol. 50, Issue 3, pp. 616–619). https://doi.org/10.1021/acs.accounts.6b00615

Sustainable Aviation. (2020). Decarbonisation Road-Map: A Path to Net Zero.

Tabak, S. A., & Yurchak, S. (1990). Conversion of methanol over ZSM-5 to fuels and chemicals. Catalysis Today, 6(3), 307–327. https://doi.org/10.1016/0920-5861(90)85007-B

Transport & Environment. (2018). Roadmap to decarbonising European aviation. In Transport & Environment. www.transportenvironment.org