The Economics of a Cookstove

The other day I went to the NWTF branch office in Hinigaran to interview clients that recently purchased an Envirofit cookstove. Cookstoves have received a lot of positive publicity recently as a cheap and effective solution to the problem of indoor air pollution – a problem that claims 1.4 million lives every year. The predominant stove in use by the poor – a basic design with a fire lit beneath a pot resting on three stones (a “three-stone stove”) – burns inefficiently. Much of the heat from the stove is lost due to lack of insulation and the fuel – sticks or charcoal – does not burn completely, requiring more to produce the same amount of heat. What’s more, partially-burnt fuel produces smoke containing particulate matter that is particularly harmful to the lungs when inhaled. The Envirofit cookstove, designed in conjunction with researchers at the University of Colorado, is the product of air-flow modeling and rigorous testing. It is designed for efficiency.

The stove is a cylinder about a foot in diameter, weighing a little more than 10 kilograms. It has 3-inch ceramic interior with a 6-inch chimney-like tube that channels the heat directly to the grill where the pot sits. The stove recirculates the fuels to make sure it burns completely, making it both cost-effective and clean. It uses half as much fuel as the typical stove it is designed to replace, and releases 80% less emissions. And, compared to an LPG (liquid petroleum gas), it is cheap. It is a product that is designed for the poorest, and has the potential to be a major success. But one of the biggest problems with products designed for the poor is that they are not economically-viable. People around the world generally use the same rationale for buying a product – all things considered, is it cheaper than the alternative. We went to interview users of the stove to find out whether this is really the case.

The alternative in the Philippines is a stove called a “kalan.” It is basically a ceramic pot with a hole cut in the bottom for airflow. The charcoal burns on a concave grill, and the pot rests on the top of the pot. It is better than a three-stone stove, but still inefficient compared to alternatives. There is no recirculation of fuel and heat is lost through the edges. But, at only 20-40 pesos per stove (USD $0.50 to $1), it is cheap. In contrast, the Envirofit stove costs 1,500 pesos (USD $30) and is financed through a microfinance loan. Accounting for interest, the true cost is closer to 1,900 pesos (USD $40). The Envirofit stove has a 5-year warranty, so it needs to generate at least $39 in savings over its lifespan to be cost-effective.

This particular Envirofit model – the B-1200 – burns wood (others burn charcoal). On average, to cook a single pot of rice requires three sticks of wood and will take 15-20 minutes. Using a kalan stove, the same pot would require at least six sticks and takes about a half an hour. Some women collect sticks on their own, some buy them at the market. One woman we interviewed cooks three meals per day and used to pay 60 pesos ($1.50) every two weeks for wood. With the Envirofit stove, she uses half as much wood, for an annual savings of 780 pesos. Based purely on fuel savings, the payback period is about two and half years. But the kalan stove is prone to breaking and needs to be replaced more often. So the real break-even for someone using the stove every day is closer to two years.

Some women end up making their money back much sooner than that. One client we interviewed has a business roasting peanuts and selling them door-to-door in her community. She uses her stove every day from 5 AM to midnight. Before, she spent 500 pesos ($10) per week on fuel. With the Envirofit, she cut it down to 250 pesos. For people using the stove in their business, the payback period can be as short as two months.

And then there were some people for whom the stove is not cost-effective at all. One woman only cooks in the morning, making all of the food for the day. Another has three stoves – a kalan, an LPG burner, and an Envirofit – and uses them equally. And another only used the Envirofit on special occasions, opting for a kalan stove the rest of the time.

People had different motivations for buying the stove. Some wanted to save on fuel costs, others thought it looked nice and was easy to clean. Some women liked the fact that it produced less smoke than their stove and that it cooked a pot of rice in less time. Most could quantify exactly how much they were saving, either in monetary terms or by comparing their fuel consumption before an after (a bundle of wood lasts twice as long). And all of the women said that they were proud to own the stove, which is probably one of the main reasons some of the decided to buy one. So owning the stove is not always financially cost-effective, but it seems like, for most of the women, purchasing it was the right decision.

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"Josh Weinstein is a visionary. I read his blog every day." - Bono
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  1. Pingback: Envirofit International | CSTS/Ayllu Energy Map

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