World Insights Bringing You best of world at one placeThe energy captured by leaves on our planet by the process of photosynthesis is about 100 terawatts – about six times the annual power consumption on our planet. Scientists have been trying to learn from nature and develop ‘artificial leaves’ for a long time – devices that could employ sunlight to split water into its elements, hydrogen and oxygen. The hydrogen thus produced can then be stored in fuel cells and used for energy production.
MIT professor Nocera and coworkers have now developed a material which works like a leaf. When the artificial ‘leaves’ are placed in water under sunlight, and connected to a fuel cell, it can supply enough electricity for a day for a small household in a developing country. The artificial leaf is claimed to produce 10 times more energy than a natural leaf.
Beautiful glass windows that can produce electricity have been developed by Sony! Dye-sensitised solar cells (DSSC) are incorporated in the material used to produce the power. In another development a Norwegian company EnSol has invented a film that can be sprayed on window glasses, thereby converting them instantly into solar panels! The film has metal nano particles incorporated into it in a composite matrix.
Another really exciting development in solar technologies is the invention of paints that can generate electricity, since solar cells are embedded within the paint. Swiss scientists have improved the efficiency of the now famous Grätzel solar cells to 12.3 percent. They used porphyrin and cobalt to achieve this high efficiency, thereby mimicking the property of photosynthesis used by plants. The cells have a greenish tint reminding us of how chlorophyll present in leaves converts solar energy.
Advances in solar cell technologies include the production of flexible solar cells. They are cheaper to produce than the standard silicon based solar cells and may alter the way we generate solar energy. Developed by the Swiss Federal Laboratories, they have an efficiency of about 18.5 percent (similar to that of conventional solar cells) and a new start-up company FLISOM has been formed to produce and market them. These cells will be incorporated on roll-out transparent sheets that can be placed on windows and walls, to absorb light and provide electricity.
Based on such technologies, aircraft are now being manufactured that can fly just powered by sunlight! A carbon-fibre ultra-light unmanned aircraft was flown a couple of years ago at a height of 5,000 ft for over 14 days to set a new world record for the longest duration flight powered by solar cells. Manufactured by Qinetiq, it was powered by thin lithium ion batteries which were charged during the day by an array of solar cells installed on the wings. The power thus stored even allowed the aircraft to fly at night, and can thus be flown continuously for months. The Germans too have built a solar-powered aircraft that can fly in the stratosphere at a height of 15 kilometres for years continuously. The aircraft ‘ELHASPA’ made its maiden flight two years ago to demonstrate the viability of the technology used. These High Altitude Long Endurance (HALE) aircrafts are expected to replace satellites as they can be manufactured at only one percent of the cost of manufacturing satellites; they can perform most of the functions of expensive satellites at a small fraction of the cost.
Another source of energy that is undergoing rapid development is from biological sources. Biodiesel can be produced from algae grown in open ponds or fermentation tanks in excellent yields. This avoids the use of precious land for growing oil producing crops. Such land can then be used for growing food crops. Those algae that have high oil content (such as the blue-green algae) can be grown in large vessels, and then harvested for their biofuel content. Since the cost of biofuels from algae remains high, intensive efforts are under way to discover new algae that can produce high quality biofuels at low cost.
One factor that contributes to the cost of biofuels is the process of extraction of the precious oil. Now scientists have developed certain genetically modified blue green algae which produce so much oil that it starts oozing out from the cell spontaneously, and can be readily collected. The process of extraction can hence be avoided.
Another important source of biofuels is cellulose. This is the most common organic material on our planet; cotton is about 90 percent cellulose while wood contains up to 50 percent cellulose. Indeed plant matter, including grass, comprises about 33 percent cellulose. This is the main component of the primary cell wall of green plants.
Certain bacteria have been found to have an appetite for cellulose and degrade it readily to two very desirable biofuels, butanol and isobutanol. This represents a major breakthrough by scientists at the US Department of Energy’s BioEnergy Science Centre (BESC). Isobutanol is a very attractive biofuel because it can be used directly in car engines without any engine modification and has similar heat value as standard petrol. Once the product is successfully developed commercially, you may be driving cars on ‘grassoline’ instead of ‘gasoline’ – a biofuel produced from grass!
Pakistan needs to invest in a major way in the field of biotechnology as it has tremendous industrial potential. The National Commission of Biotechnology was established to promote this important field, and projects of over one billion rupees were funded. However, the previous government systematically destroyed the science and technology programmes initiated by me, and stopped all the programmes of biotechnology and nanotechnology. It is hoped that the new government will re-initiate these programmes with a sense of urgency since five years have already been lost.
Another important source of energy is wind. There is potential to produce at least 20,000MW of electricity in the area in Sindh located between Kati Bander, Gharo and Hyderabad. We should commence large-scale wind turbine production within the country to solve our energy problems, in addition to switching over to coal and hydro-based electricity generating plants.
by Dr Atta-ur-Rahman
