Solar photovoltaics & solar fuels
Solar energy could account for 8–15% of global electricity in 2050, depending on factors such as market demand, energy policy, manufacturing costs and technological advances. It looks likely also to play a role in providing power to the roughly 1.6 billion people worldwide without access to the electricity grid.
Today, renewable energy accounts for over 20% of total global electricity generation, with solar ranking fourth after hydro, bioenergy and wind. The majority of solar energy technologies on the market today are based on the ‘photovoltaic effect’, whereby an electric current is produced in a material when exposed to light. Chemistry has an important role to play both in improving current solar photovoltaic technologies and developing new ones.
Another route to harnessing solar energy to produce electricity is using concentrated solar power (CSP) and the world’s first commercial solar thermal power plant came online in Spain in 2007. Projections from the International Energy Agency are that the share of renewable electricity generation from solar energy will increase from 0.3% in 2011 to almost 0.6% in 2018, of which about one-tenth will be from CSP.
Longer term there is also the possibility of using solar energy and abundant raw materials, such as water and carbon dioxide, to produce fuels and other chemicals. The goal is to produce molecules such as hydrogen, methane and methanol, currently produced from fossil fuels, in a renewable way. Solar fuels is an active field of research in the chemical and other sciences, with groups around the world aiming to deliver commercial prototypes to pave the way for a disruptive technology within 10–15 years.
Solar energy and related underpinning research in materials, photochemistry and catalysis were major themes in our 12th International Conference on Materials Chemistry and our Faraday Discussion on Next-Generation Materials for Energy Chemistry.
Bringing everything together, Sir Harry Kroto, Nobel Laureate for Chemistry and our Past President, talks on BBC World News about the future of renewable energy and how advances in harvesting the energy of the sun, such as organic solar cells and artificial photosynthesis, are being inspired by nature.
There have been ups and downs in the story of the photovoltaics industry recently, but there has been overall significant growth in the uptake of this technology. For instance, the amount of new solar photovoltaic capacity installed globally in 2013 was 30% greater than in 2012 with, for the first time, more new installations in Asia than in Europe.
In the UK, solar photovoltaic panels are now installed on over half a million buildings and the Government launched a Solar PV strategy in 2014 in order to maximise benefits for consumers, the national energy mix and the economy. The Scottish Institute for Solar Energy Research released their report on a solar vision for Scotland in 2014.
Our office in Cambridge, UK, joined this list in 2013 when Julian Huppert, our local Member of Parliament at the time, switched on our solar panels. Our installation was done by a small local company called Evogreen which we featured in an article on Panels for Pupils about installing solar panels in schools. It is also one of the many small, medium and large companies that tell a wider story about the economic opportunities associated with solar and other energy research and innovation.
In current wafer and thin-film photovoltaic technologies chemical scientists and engineers are contributing to the development of: lower energy, higher yield and lower cost routes to silicon refining; more efficient or environmentally benign chemical etching processes for silicon wafer processing and; processes to improve the deposition of transparent conducting film onto glass.
Chemical scientists are also working on improving the efficiency and lifetime of organic and dye-sensitised solar photovoltaic technologies. These technologies offer the possibility of lightweight, flexible, coloured and inexpensive solar panels. For more information about organic and dye-sensitised solar cells you might like this article in The Mole, our magazine for young people. One of the authors, Neil Robertson from the University of Edinburgh, heads a UK national Solar Spark outreach project and you can also find their resources, including how to build your own Grätzel solar cell, on Learn Chemistry.
To find out more about the chemistry and materials research underlying organic photovoltaics (OPV) read a case study developed by our Organic Division, or the report on Organic Electronics for a Better Tomorrow from the 4th Chemical Sciences and Society Summit report. Thinking of how the future may look, you can watch our Faces of Chemistry interview with researchers at a BASF laboratory working on organic solar cells for a solar-powered car.
Dye-sensitised solar cells (DSSCs) have been commercialised in niche applications such as solar-powered keyboards for tablet PCs. DSSCs is a tremendously active research area internationally and in the past year there has been a lot of excitement in particular about record efficiencies achieved in the lab for perovskite solar cells.
There are also important wider issues such as developing alternative materials, and materials recovery techniques, to reduce the dependence of solar and other energy technologies on critical raw materials or on high energy manufacturing processes. Recycling of silicon photovoltaic modules makes an interesting case study in our Resources that Don’t Cost the Earth report.
Our Energy Sector Interest Group also provides a forum to access knowledge and express views on matters relating to energy. Their conference last year on Next Generation Materials for Photovoltaics included topics in both current and next generation technologies.
Scientists around the world are also working on technologies to harness energy from the sun to produce fuels and other chemicals for transport, industry and electricity generation.
In his foreword to our 2012 report on Solar Fuels and Artificial Photosynthesis, Nobel Laureate Professor Alan Heeger wrote that, although the idea that we could produce electricity using solar energy may at one time have been considered to be a remote vision, today solar photovoltaic panels are an increasingly common sight. The vision for solar fuels is a technology that uses sunlight to produce molecules such as hydrogen, carbon monoxide and methanol from water and carbon dioxide.
What is new is not these 'fuels' themselves – which are currently produced from coal, oil or natural gas – but the idea of using solar energy directly to produce them from water and carbon dioxide. The word ‘fuel’ is used here in a broad sense, referring not only to fuel for transport and electricity generation, but also chemical feedstocks used in industrial sectors ranging from petrochemicals and fertilisers to plastics and pharmaceuticals.
The infographic demonstrates how producing and using solar fuels might work in practice. This and other solar fuels infographics are available to download in the Global challenges policy page and on Learn Chemistry.