Bosch and Siemens introduce biofuel cooking stove for developing world

Almost half of the world's population relies on fuel wood, charcoal, dung, or kerosene as fuels for cooking and heating. Most often, it is women and children who are burdened with the tasks of collecting the fuel and who prepare the food. Indoor smoke pollution from cooking on an open fire is a real killer in the kitchen. A recent analysis by the World Health Organisation shows around 1.5 million women and children die each year because of it (earlier post).

Introducing efficient and non-polluting cooking stoves therefor means a real revolution on the household level (earlier post). Biofuels such as ethanol gelfuel, biogas, biopropane and pure plant oil (PPO) may come to the rescue, and many initiatives are under way to promote their use.

Bosch and Siemens Home Appliances Group (BSH) is now testing a clean biofuel cooking stove called Protos. First experiments in around hundred Philippine households over the past year, were successful, prompting BSH to expand the project to at least ten thousand more homes. BSH has described the rollout as a “small-scale carbon project”, and is emphasizing the ability of the stove to be carbon-neutral, depending on fuel used.

The Protos plant oil cooker works as follows (image, click to enlarge): the tank is filled with PPO after which the burner is pre-heated with a small amount of alcohol or an other available fuel source. Through application of the pump, the tank is pressurized making the oil rise into the vaporizer where the heat of the flame converts the liquid into a gaseous mixture. The gas flux emits from a nozzle into a burning area, where it mixes with surrounding air and burns in a blue flame. The power output can be adjusted with a valve in the fuel line.

The stove's properties look as follows:

• Power range: 1.6–3.8 kW
• Usage: 2 liters oil per week for a family of 4-5 → 100 liters per year
• Fuel: diverse plant oils, plant oil esters
• Efficiency: 40-50%
• Emissions: ten times lower than with high quality kerosene
• CO2-balance: neutral

Protos was designed to work with a wide range of liquid fuel sources including the full range of both edible and inedible oils such as coconut oil, jatropha, sunflower oil, rapeseed oil, cottonseed oil or peanut oil. The fuel can be refined or unrefined. In addition to pure plant-oil it is also possible to burn used frying oil and plant oil esters (biodiesel):
bioenergy :: biofuels :: energy :: sustainability :: plant oil :: biodiesel :: fuel wood :: biomass :: indoor smoke pollution ::

BSHG intends to introduce the stove in areas that can sustainably harvest the fuel it requires. It can also help cut down the use of wood in deforested areas; studies show that a typical family uses up to two tons of wood per year.

Protos is estimated to require about 100 liters of plant oils annually. BSH project leader Dr.-Ing. Elmar Stumpf noted “the plant oil stove is easy to operate and offers a very safe cooking environment since plant oils can neither burn nor explode.”

Vaporization and combustion of plant oils in a simple stove involve more than 10,000 different chemical reactions, which vary for each plant oil, depending on its origin, quality, and means of extraction. The Protos burner utilizes a combustion temperature of up to 1,400°C (2,550ºF) to ensure vaporization and low-emission combustion regardless of feedstock. With plant oil carbon residues forming at more than 100 times the rate of kerosene, the stove’s burner had to be designed to maintain a temperature profile which would minimize soot formation.

Trials with the cooker have been held in the Philippines and in Tanzania, with further projects planned in India, China, Madagascar, and Sri Lanka. The stove was developed and tested with support from the University of Hohenheim, the German Environmental Foundation, Leyte State University in the Philippines, and the European Environmental Heritage Fund, among others.

More information:
BSH: Protos Plant Oil Cooker - FAQ.

BSH: Plant Oil Cooker website.

Biofuel cooking stove mailing list.