Powering Fan-Equipped Biomass Cooking Stoves by Small Solar Panels

According to World Health Organization (WHO) suspended particulate matter and other types of air pollution annually cause the premature death of seven million people. Of them, roughly four million people a year die because of the emissions liberated into the kitchens or outside air by the world’s 400 million traditional cooking stoves burning solid fuels, mostly wood and cow dung.
According to some scientists the real figure could be even higher, because for instance in Indian kitchens the amount of particulate matter in the air can reach 56,000 micrograms per cubic meter during the monsoon, when ventilation hatches are not kept open. Pollution produced by the traditional biomass cooking stoves causes emphysema, a very painfully and excruciatingly slowly killing lung-disease caused by too much coughing. The small particles and other pollutants in wood fuel smoke also contribute to the development of cardiovascular disease and increase the risk of pneumonia, chronic bronchitis, severe anemia and tuberculosis.
The highly polluting biomass cooking stoves also contribute to global warming. They may produce up to 40 per cent of the humanity’s soot emissions. This is unfortunately only a learned guess because not enough is known about the relative importance of the different sources of soot. However, if the traditional cooking stoves produce 40 per cent of the world’s soot emissions they make a major contribution to global warming, because according to the latest estimate of IPCC (Intergovernmental Panel on Climate Change) soot heats the planet by 1.1 watt per square meter. This would make soot the second most important factor in global warming, straight after carbon dioxide whose heating impact has been estimated to amount to 1.8 watt per square meter. In any case, soot emissions are the most important factor contributing to the melting of Himalayan glaciers, which is a serious threat for the dry-season flows of Asia’s most important rivers, including Ganga, Indus, Brahmaputra, Huangho, Jangtzi and Mekong.
Traditional cooking stoves typically produce 4,000 – 6,000 milligrams of suspended small particles during one round of cooking. This can be reduced to 500 – 1,000 milligrams by a better design. For example the TLUD or top-lit updraft cooking stoves are very promising. On the other hand many so called advanced or improved cooking stoves which have concentrated on energy saving and sacrificed clean burning for energy efficiency have actually produced much higher or even multiple emissions, compared to the traditional models.
The cleanest burn can be achieved by equipping a well-designed biomass cooking stove (preferably a TLUD stove, but other possibilities exist) with a small electric fan. With the best fan-equipped biomass cooking stove designs the amount of particulate pollution per one round of cooking has been reduced, according to measurements, around 30 milligrams, 100 – 200 times less than the average of the traditional models.
The problem, however, is that fan-equipped cooking stoves need small amounts of electric power, and most of the poor families that now use traditional biomass cooking stoves are too poor to have a grid connection.
Are there solutions to this problem?
Can the fan-equipped biomass stoves be designed so cleverly, that they would only need a tiny amount of electricity, perhaps only 4, 2 or 1 watt-hours for one round of cooking? If the power needs can be reduced to such a tiny level, it would become eminently possible to produce the required power by very small solar panels and related small batteries, costing only a few hundred rupies (or a few euros). Or should the power companies develop ways via which the less well-off families could purchase tiny amounts of electricity for powering the fans of their cooking stoves, even as small as 0.01 kwh, from the grid or from local entrepreneurs, for example by using their cell phones?
Could the large solar power companies subsidize the purchase of fan-equipped, clean-burning stoves and the related solar panels and small batteries?
Without governmental or private subsidies the poorest families will not be able to acquire fan-equipped biomass stoves, because the manufacturing of them costs more than the 5 – 8 euros the poorest families can afford to pay for their cooking stove, according to numerous different field studies. For the solar power companies planning to establish 6,000 gigawatts of solar power within the next 25 years it would probably be a very good investment to subsidize 400 million fan-equipped, clean-burning biomass stoves for the world’s 400 million poorest families.
The soot, fly ash and other pollutants produced by the highly polluting biomass cooking stoves reduce the production of solar power installations, possibly in a rather significant way. In the air they absorb part of the solar radiation and provide some unwanted shading for the photovoltaic panels. When they rain down on the solar panels, they again reduce their production by making their surface less transparent. The dust, ash and soot falling on the panels also increases the cost of cleaning them, especially the soot, because it tends to be sticky and difficult to clean from all kinds of surfaces. Let’s assume, as a thought experiment, that 6,000 gigawatts of solar panels will be established, and each watt of installed capacity will only produce 60 kilowatts of power during its lifetime instead of 70 kilowatts, because of the soot and ash emissions from the world’s 400 million traditional cooking stoves. This, of course, is once again only a thought experiment because there is no proper data on the subject. However, with these parameters the economic value of the 60,000 billion kwh of lost power production might be somewhere around euro 2,000 billion. This is a sobering calculation, keeping in mind that a subsidy amounting to 10 euros per stove or 4 billion euros for 400 million stoves might already be enough to provide all the world’s poorest families with clean burning stoves, assuming large-scale mass production of fan-equipped cooking stoves.
Please join us in saving the Himalayan glaciers and four million human lives, every year!