Research Scope

The current research focus is in Solar Thermochemistry: an interdisciplinary emerging field that deals with the utilization of concentrated solar energy for the

  • production of chemical energy carriers (e.g. hydrogen, syngas, metals)

  • thermal decarbonization of fossil fuels (e.g. cracking, reforming, gasification)

  • thermal processing and recycling of energy-intensive materials.

Solar Fuels

High-temperature thermochemical processes efficiently convert concentrated solar energy into storable and transportable fuels. In the long run, H2O/CO2-splitting thermochemical cycles based on metal oxide redox reactions are developed to produce H2 and CO (syngas), which can be further processed to synthetic liquid fuels. In a transition period, carbonaceous feedstocks (fossil fuels, biomass, C-containing wastes) are solar-upgraded and transformed into valuable fuels via reforming, gasification and decomposition processes. Thermochemical conversion of solar energy into chemical fuels offers an efficient path for long-term storage and long-range transport of solar energy (Fig. 1). Concentrated solar energy is used as the source of high-temperature process heat for driving endothermic reactions. Concentrating solar technologies – e.g., solar towers and dishes, applied commercially for large-scale power generation – coupled to chemical reactors, have the potential of reaching solar-to-fuel energy conversion efficiencies exceeding 50%, and consequently, producing solar fuels at competitive costs.
Figure 2 illustrates possible solar thermochemical pathways to produce hydrogen or syngas from water and/or fossil fuels. Feedstocks include inorganic compounds such as H2O and CO2, and organic sources such as coal, biomass, and natural gas (NG). The forms of solar fuels are H2, synthesis gas (syngas, with H2 and CO as main constituents), and their derivatives such as methanol, gasoline, diesel, and kerosene.

Solar fuels production technologies are in an earlier stage of development than commercial solar thermal electricity generation plants (CSP), but they will make use of the same solar concentrating infrastructure. Typically, the solar reactor technology is being developed at laboratory scale of 1-10 kW solar thermal power input. Scaling up thermochemical processes for hydrogen production to the 100 kW power level is reported for metal-oxide based cycles. Pilot plants in the power range of 300-500 kW have been built for the carbothermic reduction of ZnO (SOLZINC), the steam methane reforming of methane (SOLREF), and the steam gasification of petcoke (SYNPET) and carbonaceous waste (SOLSYN). Solar produced fuels via thermochemical processes can become competitive with conventional fossil-fuel-based processes at current fuel prices, provided credits for CO2 mitigation and pollution avoidance are applied.

Solar Materials

The conventional extraction of metals from their oxides by carbothermic and electrolytic processes is characterized by its high energy consumption and its concomitant environmental pollution. The extractive metallurgical industry discharges vast amounts of greenhouse gases and other pollutants to the environment, derived mainly from the combustion of fossil fuels for heat and electricity generation. These emissions can be substantially reduced, or even completely eliminated, by using concentrated solar energy as the source of high-temperature process heat. The thermal dissociation and electrothermal reduction of metal oxides proceed without reducing agent, while the carbothermal reduction of metal oxides uses solid carbon C(s) or gaseous hydrocarbons (e.g., CH4) as reducing agents.

  • Solar metals and metal oxides; metallic carbides and nitrides
    (Examples: Solar processing of aluminum, silicon, and zinc)

  • Solar fullerenes and carbon nanotubes

  • Solar thermal recycling of hazardous waste materials
Technical information:
Solar Energy in Thermochemical Processing
Meier A., Steinfeld A.
Encyclopedia of Sustainability Science and Technology, Robert A. Meyers Ed., Springer New York, 978-0-387-89469-0 (Print) 978-1-4419-0851-3 (Online), 9588-9619 (2012)

A Review of High Temperature Solar Driven Reactor Technology: 25 Years of Experience in Research and Development at the Paul Scherrer Institute
Koepf E., Alxneit I., Wieckert C., Meier A.
Applied Energy, 188, 620-651 (2017)