Power plants!
Toby Ferenczi reports on the latest attempt to find a clean energy source
For years scientists have been looking hard for a clean, sustainable energy source without ever noticing the great big one sitting in their back garden. Seriously.
All the time we've been raping our planet's natural resources and pumping billions of tonnes of waste into the air, plants have been happily using the sun to get their energy. Perhaps we should pause momentarily and see what we can learn from our green co-habitants?
This was the premise of a talk given last Wednesday by Daniel Nocera, the W.M. Keck Professor of Energy at MIT. Nocera's work involves modelling and testing biological processes related to photosynthesis. By understanding the underlying chemistry we might then be able to design reactions which utilise the sun's energy. Nocera's idea is to separate the hydrogen and oxygen found in water through photocatalysis, so that these two ingredients can be recombined in a fuel cell to deliver power on demand.
The trouble is that these chemical processes are extremely complex and far beyond current understanding. Nocera predicts that it may take up to 50 years before we have the required knowledge to develop this technology.
During his introduction, Nocera set out the case for attempting such a gargantuan undertaking. Careful to distance himself and his opinions from his statements, he presented a torrent of charts and figures which added a convincing air of legitimacy to the arguments.
According to the UN World Energy Assessment, we were using 12.8 terawatts of power in the year 2000. According to a study by Hoffert et. al (Nature 1998), by 2050 that figure will be somewhere between 28 and 35 terawatts. This phenomenal rate of energy consumption may be met by fossil fuels for sometime yet, says Prof. Nocera, who believes that fears of imminent shortages are overplayed in the media and by industry.
So with this safety net, why should we care? Why don't we just carry on as we are? "I'll tell you why we should care," Nocera says, "It's a fact that CO2 levels are rising." Currently the concentration of carbon dioxide in the atmosphere is at 380 parts per million (ppm), the highest it has been for 400,000 years, and by 2050 will be at 550 ppm. "The people who say Global Warming isn't a problem are the biggest risk takers and gamblers you'll ever meet. We are doing an experiment with the Earth." His point is that as we have no way of predicting the effects of this increase, to dismiss all concern may be perhaps somewhat foolhardy.
So what can be done? According to him, solar energy is the only sustainable form of energy that can be scaled up in the long term to meet our future requirements. Using all remaining cultivatable land on Earth for biomass energy might deliver 712 TW of power. Building wind farms at all suitable locations would give you a maximum of 2.1 TW worldwide and in order to deliver 8 TW from nuclear energy by 2050 we would need, on average, to open one new nuclear power plant every two days between now and then.
In contrast, the sun deposits around 800 TW of power on the Earth's land masses. More sunlight hits the land in one hour than the energy we use globally in a year. Nocera is quick to point out that this is not to say other technologies are not worth investing in, we will need every drop of clean energy we can get to stop emissions rising catastrophically, but that to maintain the lifestyle to which we have become accustomed, society will eventually be forced to look to the sun.
Speaking in 1912, the Italian chemist Giacomo Ciamician envisioned "industrial colonies without smoke and without smokestacks" and a world where energy is derived through sunlight and photochemistry. Unfortunately today, this scenario is disappointingly distant. Renewable energy sources make up only a small fraction of our total consumption and petro-chemical organisations do not appear to be hesitating in developing new oil fields.
Scientists involved in alternative energies such as Prof. Nocera also complain of a lack of political will in dealing with this issue. Apparently, if everyone in the US stopped driving for ten minutes, the amount of money saved in fuel is equivalent to the total US investment in renewable energies.
Because global warming and the depletion of fossil fuel reserves operate on different timescales, market forces alone will not bring the required change soon enough. If we want to make significant inroads into limiting carbon emissions, it appears that a conscience effort is required on the part of society to act above the individual. Whether humans are capable of doing this or not is perhaps a matter for debate. However, it might be advisable that we try, given that the Earth's habitability is at stake. In closing, I point to how Nocera began his lecture with Ciamician's idea that, "If our black and nervous civilization, based on coal, shall be followed by a quieter civilization based on the utilization of solar energy, that will not be harmful to progress and to human happiness."
Professor Nocera's lecture was given as part of the Energy Futures Lab initiative at Imperial. A recording of the lecture may be found at www.imperial.ac.uk/P7395.htm.
