Solar Fuels

Background
Solar Energy is the world's largest renewable energy resource; the solar irradiation on the plant in one hour exceeds our current annual global energy demand. Existing solar conversion technologies achieve the conversion of solar energy to electricity (photovoltaics) or heat (solar thermal). Both technologies are making rapid scientific and technical progress, and achieving substantial market growth. For example 6.4 x 10^10 W of photovoltaic (PV) systems had been installed in > 100 countries by December 2011. However these solar conversion technologies have two significant limitations - the lack of a viable, scale-able energy storage strategy to address the intermittency of solar irradiation - and the lack of a viable mechanism to convert sunlight into transportation fuel. Given that transportation currently comprises ~ 1/3 of global energy demand, this latter limitation is of particular concern.

Plant photosynthesis demonstrates the viability of the direct conversion of sunlight to chemical fuels, storing the incident solar irradiation in the form of chemical bonds. However the relatively low solar to biomass energy conversion efficiencies of natural photosynthesis, and the limited availability of suitable cultivatable land, limit the global potential of direct bioenergy conversion. As such, artificial photosynthetic strategies are attracting extensive interest for the development of chemical reactors capable of utilising sunlight to drive the synthesis of molecular fuels.

The production of fuels (H2, HCO2H, CH3OH, CH4 etc.) using solar energy is now a very rapidly developing research field internationally. It is highly inter-disciplinary and multi-disciplinary, encompassing a range of scientifically distinct approaches to solar-driven synthesis of molecular fuels. Whilst the potential role(s) of solar-driven fuel synthesis within the overall parallel challenges of solar energy utilisation and renewable fuel synthesis needs to be clarified, there is increasing appreciation of the importance of meeting these challenges, and recent impressive scientific advances in the solar fuels field, are driving this field very rapidly up the scientific, commercial and policy agendas.

Network Focus
The Solar Fuels Network will focus on direct photo-driven fuel synthesis strategies. These include photoelectrochemical, molecular and photocatalytic strategies. Developing these strategies requires bringing together a range of disciplines including photoelectrochemistry, redox catalysis, molecular and semiconductor photochemistry, materials and particularly nanomaterials design and synthesis, photoreactor design and engineering as well as technology, environmental and lifecycle analyses.

Whilst the Network will focus on direct photo-driven processes, it is important to recognise that advances in this field will most probably be dependent upon advances in wider research fields, including electrocatalysis, biological photosynthetic processes, semiconductor photocatalysis and photovoltaics. Furthermore, assessment of solar fuels technology applications will require interfacing with, and evaluation against, alternative or complementary fuel synthesis strategies including water electrolysis, thermochemical CO2 reduction, CO2 capture, fuel cells, solar cells and alternative energy storage strategies. As such, the Network will plan to work closely with these research communities, including in particular organising joint events with suitable partner programmes and organisations - for example, the CO2 Chemistry and Semiconductor Photocatalysis Networks, the Hydrogen and Fuel Cell, Storage, Bioenergy and Solar Supergen Hubs, the EG&S and Nanotechnology KTN's, the Royal Society of Chemistry etc.

In addition to its impact on the academic artificial photosynthesis research community, Tthe network will also address the wider challenge of developing UK science and technology roadmaps on solar to fuels, and how this technology can contribute to reductions in green house gas emissions both within the UK and globally. In this regard, we will work with other EPSRC funded hubs and networks addressing complimentary science and technology issues, as detailed in the case for support, including the CO2 Chemistry and Semiconductor Photocatalysis Networks, the Hydrogen and Fuel Cell, Storage, Bioenergy and Solar Supergen Hubs. Members of the network are already closely engaged with international initiatives on solar fuels (including for example EuChemS and the US JCAP and Solar Fuels Institute) enabling us to maximise synergies, and the global impact, of network activities. Both the RSC and Foreign and Commenwealth Office's Science and Innovation network have expressed interest in working with network to enable its global engagement, including the sponsoring of international and bilateral meetings (see supporting letters).

Of particular importance in maximising the impact of this network will be engagement with the Royal Society of Chemistry. The applicants already have a strong record of working with the RSC to raise the profile and coherence of solar fuels research in the UK and in initiating discussion of a UK roadmap in this field. The RSC has expressed a strong commitment to working with the solar fuels network to maximising our joint impact in this area, including:
- Continued support to UK community-building, including, for example, partial financial support for meetings.
- Running RSC organised solar fuels meetings, including international conferences, workshops and bilateral meetings.
- Publicity and dissemination activities through RSC journals, magazines and websites.
- Policy focussed events and drafting of policy documents.

The applicant's activities to date in conjunction with the RSC have already had a very strong track record - with the launch of the RSC's policy document on solar fuels, and the associated meeting, receiving extensive interest in both the scientific and popular press (see letter of support from RSC for details).

The application PI, Prof Durrant, has a strong track record of working with the RSC on solar fuels, and also sits on the RSC's Environment and Sustainable Energy Committee. Several advisory board members are closely associated with RSC activities in this area already, including Anthony Harriman (RSC's Solar Champion) and Mercedes Maroto-Valer (Chair of RSC's Energy Sector committee). Beyond the RSC, Professor Durrant already has experience in integrating and co-ordinating activities across the energy sector through his role as Deputy Director of Imperial's Energy Futures Lab. The applicants moreover cover all the main subject disciplines relevant to solar fuels research - comprising Chemistry (Durrant), Materials (Riley), Chemical Engineering (Kelsall) and Biochemistry (Barber), thus enabling the network to maximise its engagement in all of these disciplines.

Outreach and dissemination activities will be a key function of the network. Currently the challenge of renewable fuel synthesis, and solar driven fuel synthesis in particular, is not widely appreciated by the wider scientific community, policy makers and the general public. In this regard, several members of the network already have strong track records in such outreach and dissemination activities including including Professors Parkin and Sella at UCL, Cogdell and Cronin at Glasgow and Rutherford, Riley and Barber at Imperial. Building upon this strength, we will work with our partners organisations (RSC, EG&S and Nano KTN's and FCO's Science and Innovation Network) and facilitate and encourage all network members to engage in outreach and dissemination activities.