The Europeans are serious about nanotechnology to wean countries off using fossil fuels in the next century. There¬¥s considerable interest in setting up a solar grid that is global because the sun consistently shines on some part of the planet.
The technologies European scientists say are going to dominate the sustainable energy sector include Dye Sensitized solar Cells (DSCs) and biomimetics. These two technologies are popular because they show great promise for capturing or storing solar energy. At the same time, nanocatalysis already has begun to churn out efficient methods for energy-saving industrial processes convincingly.
The ground tone at the recent European Science Foundation conference about Nanotechnology for Sustainable Energy was overly clear about it; Europe is ready to accelerate development of nano technologies. The conference focused on solar rather than other sustainable energy sources such as wind, because that is where nanotechnology is most applicable and also because solar energy conversion holds the greatest promise as a long-term replacement of fossil fuels.
Solar energy can be harvested directly to generate electricity or to yield fuels such as hydrogen for use in engines. Such fuels can also in turn be used indirectly to generate electricity in conventional power stations. “The potential of solar power is much, much larger in absolute numbers than that of wind,” according to Professor Bengt Kasemo, who chaired the conference and who is attached to the Chalmers University of Technology.
A drawback of solar energy is that it -like wind energy- varies greatly across time and geography. That’s because it is confined to the daytime and less suitable for regions in higher latitudes, such as Scandinavia and Siberia. For this reason there is growing interest in the idea of a global electricity grid according to Kasemo.
“If solar energy is harvested where it is most abundant, and distributed on a global net (easy to say – and a hard but not impossible task to do) it will be enough to replace a large fraction of today’s fossil-based electricity generation,” said Kasemo. “It also would solve the day/night problem and therefore reduce storage needs because the sun always shines somewhere.”
Sources at the conference and independent organizations say that in the immediate future, solid state technologies based on silicon are likely to predominate the production (manufacture) of solar cells, but DSC and other “runners ups” are likely to lower costs in the long term, using cheaper semiconductor materials to produce robust flexible sheets strong enough to resist buffeting from hail for example.
Although less efficient than the very best silicon or thin film cells using current technology, their better price/performance has led the European Union to predict that DSCs will be a significant contributor to renewable energy production in Europe by 2020. The DSC was invented by a Swiss professor, Michael Gr√§tzel, from the Swiss Federal Institute of Technology at Lausanne, who was one of the speakers and vice chair at the ESF conference.
One key point to emerge from the ESF conference is that there will be growing choice and competition between emerging nanotechnology-based solar conversion technologies. “I think the important fact is that there is strong competition and that installed solar power is growing very rapidly, albeit from a small base,” said Kasemo.”This will push prices down and make solar electricity more and more competitive.”
Some of the most exciting of these alternatives are biomimetics, which involves mimicking processes that have been perfected in biological organisms through eons of evolution. Plants and a class of bacteria, cyanobacteria, have evolved photosynthesis, involving the harvesting of light and the splitting of water into electrons and protons to provide a stream of energy that in turn produces the key molecules of life.
Photosynthesis can potentially be harnessed either in genetically-engineered organisms, or completely artificial human-made systems that mimic the processes, to produce carbon-free fuels such as hydrogen. Alternatively, photosynthesis could be tweaked to produce fuels such as alcohol or even hydrocarbons that do contain carbon molecules but recycle them from the atmosphere and therefore make no net contribution to carbon dioxide levels above ground.
Biomimetics could also solve the longstanding problem of how to store large amounts of electricity efficiently. This could finally open the floodgates for electrically-powered vehicles by enabling them at last to match the performance and range of their petrol or diesel-based counterparts.
Because in spite of all the excitement, the commercial realisation of biomimetic and other emerging technologies is still quite far off. But meantime nanotechnology has an important contribution to make, improving the efficiency of existing energy-generating systems during the transition from fossil fuels.
The Massachusetts Institute of Technology (MIT) presented a virus based type of solar electricity. The presentation by Angela Belcher showed the details of a type of virus that infects E.coli bacteria (a bacteriophage) capable of coating itself in electrically-conducting materials like gold. This can be used to build compact high capacity batteries, with the added advantage that it can potentially assemble itself, exploiting the natural replicating ability of the virus. The key to the high capacity in small space lies in the microscopic size of the nanowires constructed by the viruses – this means that a greater surface area of charge carrying capacity can be packed into a given volume.