Some 2.5 billion people – more than one third of the Earth’s population – prepare their food over an open fire. In other words, they use firewood, charcoal, kerosene or gas – all of them raw materials that are becoming scarcer and more expensive. Moreover, burning these fuels produces the greenhouse gas CO2, which contributes to climate change. Additionally, since the most readily available and cheapest fuel is wood, new problems arise as a result of deforestation: the land loses its natural protection against erosion, which can in turn lead to serious natural disasters. There were therefore good grounds for BSH Bosch und Siemens Hausgeräte GmbH – a joint venture founded by the two big-name German companies in 1967 – to seek an alternative to traditional fire-making: “We had long been investigating the idea of using plant oil to operate simple cookers,” says Samuel N. Shiroff, who is responsible for the project at BSH.
The first product of these efforts was the Protos plant-oil cooker, which was developed between the end of 2004 and April 2006 in collaboration with the Leyte State University in the Philippines and then tested in 100 households on the Philippine islands of Leyte and Samar. The practical trials were so successful that further projects are now running in other regions of the Philippines, India and Indonesia. “More than 1,000 cookers were operating in 2007,” says Shiroff. “Now, however, we have developed an even more powerful and more economical Protos model.” The inventors also have great expectations of Protos II: “We plan to produce several thousand of these next generation cookers in 2009.”
At a time when cars are being powered by biofuels, operating a cooker with plant oil doesn’t really sound particularly spectacular. But it is, nonetheless: “Developing a functional and viable oil cooker was a technological challenge,” says Shiroff. On one hand, the flash point of the viscous plant oil is 188 degrees Celsius, over one hundred degrees higher than that of kerosene, for example. On the other, sooty residues regularly clogged up the jets of the first test cookers. Researchers at the University of Hohenheim spent years trying to crack this “nut” – in vain, it initially seemed. “We were on the point of giving up,” recalls the project leader of the time, Professor Werner Mühlbauer. Yet his assistant Elmar Stumpf carried on experimenting until he found the ideal design. The oil cooker doesn’t produce soot, doesn’t smell, doesn’t explode and, importantly, because it no longer has any complex jets, doesn’t clog up at all either: if the jets get dirty, the 0.3 to 0.5 millimetre openings can easily be cleaned with a simple piece of wire.
The principle on which the new plant-oil cooker works is actually very simple. An air pump is used to build up the pressure in a tank filled with oil. This forces the oil into the stainless steel vaporizer tube where it is vaporized by the heat of the flame. The now gaseous fuel escapes through a jet, mixes with the ambient air in the combustion chamber and burns with a blue flame. The cook can easily adjust the strength of the flame using a valve in the oil pipe. When the cooker was ready, the German household appliances group pondered on who was going to produce the oil it needed to burn: “We had to ensure that the necessary plant oil was available everywhere,” reports Shiroff about the initial phase in the Philippines. “So we looked for a coconut cooperative that was willing to work with us. Now the farmers sell their oil directly and even achieve higher revenues than before.”
The exceptional cooker can operate with unrefined and refined plant oils, such as coconut oil, sunflower oil, rapeseed oil, jatropha oil, castor oil, cottonseed oil and peanut oil – in other words, with replenishable raw materials from the regions in which it is used. “We’ve made it a rule only to sell the cooker in regions where using oils as fuel will not have any detrimental effects on the environment or human nutrition,” clarifies the BSH press office. In addition to that, the German home appliances group is also pursuing the strategy of having the Protos produced locally as far as possible. As part of the three-year test phase, workshops in the Philippines were selected to produce the cookers and train specialists to promote and sell the Protos as well as familiarize roughly 1,000 households with the cooker. Today some 1,500 cookers a year can be manufactured in the Philippines. In addition to the economic and social advantages, the German-developed plant-oil cooker also reduces damage to the environment. Cooking with plant oil is largely carbon neutral. Because the cooker does not run on fossil fuel, each unit saves one tonne of CO2 emissions a year.
