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To achieve cookstove scale we need standards

“Time to come together to make smart decisions about cookstoves.”  — Dean Still, Aprovecho Research Center.


“Rocket stove, make me lunch.”


Of all the improved cookstoves currently in use around the world, the rocket stove is probably the best known and perhaps the most imitated. And with good reason, too. A well-designed and well-built rocket stove can cut fuel consumption and emissions in half, sometimes more, depending on the fuel and combustion type. The stove, which can be modified to burn wood, charcoal, and briquettes, has been adapted to prepare the traditional meals of many cultures: injera bread in Ethiopia, tortillas in Guatemala, and, nan bread in India. You wouldn’t be wrong to think of the rocket stove as the Swiss Army knife of improved cookstoves.

If imitation is indeed the most sincere form of flattery, then you’d think the stove’s creators would be thrilled about its success.

StoveTec’s woodburning rocketstove


It’s been a real eye opener,” Dean Still tells us over the phone.

Still heads the Aprovecho Research Center, a sort of Manhattan Project for stove testing and design in Oregon where the stove was first designed and built back in the 80s.

Clarifying his statement, Still says he doesn’t object to others imitating the stove. In fact, as a humanitarian, he’d like to see the stove deployed everywhere it’s needed across the world. The problem arises when the stove is poorly copied, which happens too often. The technology is not complex but a deviation of one centimeter can have major effects on the stove’s performance. Using inferior quality material can reduce the stoves life expectancy to just a few months.

The result can be a stove that underperforms and falls short of expectations among end users and investors, which, in the case of many stove projects, is usually an international development agency or a non-profit.


The rocket stove principle


“We want stoves that meet minimum standards so that people and donors can be assured that when they invest in a stove solution, they know what they’re getting.”

Lack of standards may also be the reason why less than 10 million stoves were deployed in 2009, according to the Partnership for Clean Indoor Air. The figure is woefully below the 177 million units that the WHO says must be distributed to cut in half the number of people without access to improved stoves worldwide.

Still has devoted the last quarter century to developing stoves for the world’s poor and you can tell he is wading waist deep in the wreckage of bad stove concepts, poor execution, and unfulfilled performance expectations.

Granted, he says, there have been many success along the way. But the downside of failed projects is a donor community that has grown skeptical of stove projects that overpromised and under-delivered solutions to reduce mortality from indoor air pollution-induced, alleviate poverty, and protect the environment.

This time it’s different

Yet despite the collective roller-coaster for the stoving community, Still thinks this time it may be different. One reason the tide may be turning is Climate Change. That’s because a growing number of scientists have identified black carbon (BC), a major byproduct of inefficient biomass combustion, as an important contributor in Climate Change.

Black carbon in soot is the dominant man-made absorber of solar radiation in the atmosphere. It is approximately 1 million times stronger than CO2 per mass unit of mass – and contributes to the warming of the atmosphere at the global level. Black carbon also warms the atmosphere by absorbing thermal infrared radiation from the ground and within clouds. Furthermore, because it directly heats surfaces on which it is deposited and changes surface albedo (surface reflectivity), black carbon is a major contributor to the accelerated melting of Arctic sea and land ice, glaciers and seasonal snow covers.

The upshot is that black carbon has a much shorter average atmospheric life time than CO2 and other GHGs (on the order of days to weeks for black carbon versus years to centuries for most GHGs). Recent studies identify black carbon as the second- or third-largest overall contributor to current human-driven global warming, surpassed only by carbon dioxide and possibly methane. A disproportionate share of the disease burden associated with black carbon sources is borne by women and young children who spend a larger share of their time indoors and are thus subjected to higher exposures.

Beyond the link between cookstoves and Climate Change, a lengthy New Yorker article published last year that prominently featured Aprovecho’s work was the clearest sign yet that the stove movement — and the problems it seeks to address — are finally gaining public attention.

The January earthquake in Haiti has also drawn much attention to the link between energy poverty, unsustainable biomass use, environmental degradation, and humanitarian disasters.


An atmospheric brown cloud (ABC) hangs over Asia, disrupting the monsoon season and creating in food insecurity.


Compared to reducing atmospheric CO2, cutting BC emissions may prove to be a quicker and less expensive solution for reducing climate change.  According to a recent USAID study, of all the intervention methods available to cut BC by heavy emitters like India and China – ranging from retrofitting polluting diesel engines, two-stroke engines, and switching to CNG to power vehicles – swapping inefficient cookstoves and improving biomass fuels provide the highest mitigation cost effectiveness as measured in $/tCO2eq.

The 40,000 feet perspective on standards.

Few institutions outside Aprovecho have the breadth of experience developing and testing cookstove technologies. After more than three decades developing and improving them, one thing is clear, says Still, “there is not one cookstove solution, there are many, depending on their use.” One of the main differences is a stove’s fuel consumption and emissions performance. This is why coming up with benchmarks and standards for fuel consumption and emissions is an urgent mission for the stoving community, says Still, who points to the good work being done in this area by groups like PCIA, the Partnership for Clean Indoor Air.

Standards for cookstoves do exist, nonetheless. Some of them have been developed by Aprovecho as an important measure of a stove’s performance. These benchmarks, like the Water Boiling Test (WBT), are used to evaluate a stove’s performance while completing a basic task. In the case of the WBT, a stove is made to “simulate” meal preparation by boiling five liters of water and simmering it for 45 minutes. The test is designed to measure the stove’s heat transfer and combustion efficiency, which are then measured against a benchmark.

[EDITORIAL NOTE: Aprovecho and Shell Foundation, a longtime player in the indoor air pollution abatement field, have proposed benchmark for fuel use, Carbon Monoxide (CO) and Particulate Matter (PM) emission. These benchmarks are designed to complement the WBT. The PCIA is leading the charge on benchmarks.]

While easy, quick, and inexpensive, the WBT only measures one aspect of the stove’s technical performance, not necessarily what the stove can achieve in real households under real conditions.  A Controlled Cooking Test and a Kitchen Performance Test have been developed to provide more practical testing results.

But before the stoving community can develop the perfect universal test for determining a stove’s performance, it must first answer a fundamental question, which is, what’s more important, reducing fuel consumption or reducing black carbon and other noxious emissions.

The answer is, of course, both, but designing a stove that meets the highest current ratings in emissions reduction and energy consumption at a reasonable cost has so far proven elusive. Coming up with the right standards will be critical to getting cookstove projects to scale, especially since carbon-credit financing will be vital for some projects to make financial sense.

In a way, the future of cookstove adoption worldwide may very well depend on getting the cookstove standards right.

“If you want to reduce fuel use, then you can make a stove that does that for not a whole lot of money, Still says. But if you want to reduce emissions, then the stove is going to cost a bit more. Probably more than individual families can afford to pay, which means it will have to be subsidized one way or another. This also means governments will need to make this a priority because the cost of a low emission stove may be above a market driven price.”

Keeping both eyes on the ball

When I ask Still if he ever tires of the geologic pace at which things move in the development world, the petty infighting within a chronically underfunded movement, and the frustration of laboring in a field that has yet to gain the notoriety of more high-profile causes like the HIV-AIDS, or malaria eradication, he answers simply, “no.”


Maria Luisa Velasquez Cooking. Finca Santa Anita, Guatemala,1998



“This is about real people, women and children, dying for lack of access to a simple fix,” he says.

The real face of this is when you go to Guatemala, like I did last year with Dr. Kirk Smith. You walk into these little villages. It’s beautiful outside. They sky is blue. They have their little plot of corn. You walk into a house and there are six kids, and three of them are coughing their guts out, and one of them has such accute pneumonia that you have to rush the child to the hospital.  The family is too poor. The wife has six kids, and she has to work the farm, and so she is condemned by poverty to watch her kids die. And that’s because of the carbon monoxide and the damn smoke.”

So what will it take to get move this issue higher on the development agenda?

The math and the science have not been there to show how serious the problem is. The donors want to make sure that their money is well spent. They say, “I’ve got malaria, HIV, and you say there’s a problem but you can’t prove it? You say that a stove is going to help, but, you say you can’t prove that either?”

The good news is that big steps are underway that should help solidify the case for energy efficiency cooking technology and improved fuels.

One important step is the imminent publication of a decade-long study that will help make the case for energy efficient and emissions-reducing stoves. The study, by Dr. Kirk Smith of UC Berkeley, is expected to make the definitive case that eliminating indoor air smoke should be an urgent public health priority.

Additionally, India recently launched a national program that is designed to put millions of improved cookstoves in the hands of the energy poor. A project on this scale should yield valuable practical experience.




Finally, several large conservation organizations are exploring the feasibility of launching  national biomass energy efficiency programs across the entire supply chain of countries where biodiversity is under serious threat. The idea is to make stove projects replicable around the globe.

And, on an editorial note, The Charcoal Project is partnering with a university to jointly carry out a global cost-benefit analysis study that would show the true social and environmental cost of continuing to burn biomass under a business-as-usual scenario.

So, what now, Dean?

We have been manufacturing stoves that cut fuel use and emissions in half. But now the health and climate change communities want us to make stoves that have the same fuel use but also reduce emissions by say 90%. This means we have to be very rational now and make good decisions, because the bar has been raised for very good reasons.

And that’s why, my brother, we have a lab. That’s why we have to be understated, not overstated. Most importantly, we have to be together, pull together, and not exaggerate. We have to make a new generation of great stoves that are also loved by cooks, that make great food while protecting both cooks and our fragile planet.


Dean Still


Watch a video of Aprovecho’s rocket stove:


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