Overview of BURN stoves
BURN Manufacturing designs, manufactures, and distributes a line of fuel-efficient cookstoves in East Africa, with plans to expand to other parts of the continent. With a manufacturing facility in Kenya, BURN describes itself as “the only vertically integrated modern cookstove company in Sub-Saharan Africa”. It has sold over 950,000 stoves, which it distributes through a number of channels.
Giving Green recommends BURN stoves on the weight of strong randomized controlled trial (RCT)
evidence in support of the causality of emissions reductions, as well as demonstrated co-benefits.
Theory of Change
The following theory of change maps the link between BURN stoves and reduced GHG emissions. While BURN primarily sells its stoves in the market, its offsets fund projects that provide stoves to households at heavily reduced prices (or for free.) Offsets contribute to all facets of these projects, including production, consumer engagement, to stove distribution. Increased stove usage over time leads to reduced GHGs over time as consumers switch from their traditional cookstove to BURN’s fuel-efficient cookstoves.
We also lay out key parameters we use to model the cost-effectiveness of purchasing offsets from BURN.
The use of BURN’s cookstoves avoids emissions that would have been released by less fuel-efficient methods of cooking.
As mentioned in our overview of cookstove offsets, the academic literature on the link between efficient cookstoves and reduced emissions is mixed. Recently, a rigorous RCT was conducted on the impact of BURN stoves. Berkouwer and Dean (2020, referred to as BD) conducted a trial of BURN stoves, and found that charcoal fuel usage, as measured by weighing of ashes and by self-reported use, declined by around 39%. This is close to BURN’s claims of a 50% reduction in fuel usage. Additionally, a smaller experiment involving 154 stove users confirmed that these reductions in fuel use persisted 18 months later. We would have liked to see long-term usage data from their larger RCT sample to verify the persistence of fuel use reduction, but we view these results as encouraging. BURN has confirmed that the offsets sold on their website are generated from the same stove model studied in this RCT.
Overall, we view the evidence on the causality of BURN stoves in reducing GHG emissions to be quite strong.
Project-level additionality seeks to answer the following question: would BURN exist and sell stoves in the absence of offsets? The answer is clearly yes - BURN has a thriving business where a majority of its revenues are from the sale of its stoves. Offsets are just a small part of its income, estimated at roughly 2-3% of total revenues. Representatives from BURN claim that offsets are an unreliable source of income, and therefore they cannot rely on income from offsets to fund their core business.
However, offset money is generally tied to specific projects that distribute stoves among populations that normally would not have access to them. These stoves are delivered at reduced prices (or sometimes given away for free), and the projects would likely not exist without donor money.
Overall, our assessment is that BURN offsets have a medium level of project-level additionality, as it’s difficult to verify whether offset money is directly going to projects that distribute stoves for free or reduced prices. However, it seems quite likely that the offset market is necessary to make these special projects feasible.
Marginal additionality is achieved when each offset purchased directly leads to additional emission reductions. For BURN, there is certainly potential for each additional offset sold to lead to more stoves being sold or used. While offsets are generated from previous projects, showing a market for offsets allows BURN to continue developing and marketing new projects with subsidized stoves.
However, money is fungible. BURN could book money from offset sales as profits or raise salaries. They could also invest in marketing strategies that do not work. BURN, however, is a social enterprise with multiple impact investors on its board. They claim that their mission is to improve and distribute cookstoves, rather than to make money. They also claim that all of their offset projects are “break-even”, and do not contribute to other parts of BURN’s business. While we cannot verify their claim of using offset revenues to increase stove distribution, we find the claim consistent with BURN’s expansion strategy so far, and believe that additional revenue earned will be put toward putting more stoves in the hands of families.
Overall, it is not possible to verify with certainty that an additional offset purchased leads directly to additional stoves being purchased, and therefore to reduction of GHGs in the atmosphere. However, BURN is a social enterprise, and we believe that it is likely that with more revenue, they will increase stove distribution.
Fuel use reduction from clean cookstoves represents permanent decreases in emissions.
Beyond reducing GHG emissions, BD (2020) also found clear economic benefits for households using BURN stoves. BD estimate that purchasing a BURN stove results in fuel savings of $199/year, which is equivalent to one month of their study respondents’ income. BURN stoves can make a real difference in a family’s spending power.
Lowered fuel usage could also lead to improved health, as better indoor air quality could decrease incidence and severity of respiratory diseases. BD find that BURN stove users self-report better respiratory health than those who did not use BURN stoves.
Giving Green independently conducted an analysis using external data to estimate the cost per ton of CO2 removed from the use of BURN’s fuel-efficient cookstoves. Our goal is to validate our recommendation of BURN as a highly effective agent in reducing GHG emissions. The data we use comes primarily project-level data from BURN, as well as impact estimates from from Berkouwer and Dean (2020). Our model can be viewed here.
The RCT conducted by Berkouwer and Dean (2020) concluded that study households annually spent 39% less on charcoal, which translated to a reduction of 331 kg in charcoal per household per year, given local charcoal prices at the time of the study. The Food and Agriculture Organization (2017) estimates that for each kg of charcoal, between 7.2–9.0 kg of CO2e are emitted from the production process alone. Combustion adds an additional 2.36 kg of CO2e (Bhattacharya et al. 2002). Taking the midpoint of the former range, we estimate that each stove avoids 3.46 metric tons CO2e per household per year.
Current lifetime analyses based on testing data and field data from BURN show that the predicted lifetime of their basic stove is 4.4 years. Adding a 3% future carbon discount, our final estimate of GHGs avoided per household is 14.08 tCO2e over the lifetime of the stove. To then obtain the offset dollars required per tCO2e avoided, we incorporate BURN’s production-to-delivery cost of $50.85 USD, which is their estimate for offset-funded projects. Dividing this quantity by 14.08 tCO2e, we estimate that $3.61 USD in offsets avoids 1 ton of CO2e.
Table 1: Key model parameters.
This number is less than the price at which BURN sells an offset for a ton of CO2 on their website, and shows that offsets from BURN are highly cost-effective. (This price varies over time but was set at $20/ton in October 2021.) There are multiple reasons why our final estimate is not equal to the costs stated on BURN’s website:
Despite the stove’s estimated lifetime of 4.4 years, the crediting period for BURN is shorter because not all stoves will last 4.4 years, and as a result, it does not make financial sense to conduct the validation exercises needed to issue credits once a non-negligible proportion of stoves have failed.
There may be differences in which parts of the charcoal life cycle are accounted for in the estimation of GHG averted—combustion, or combustion plus production. According to BURN, they were conservative in their submissions to offset certifiers, and once these parameters have been submitted to a crediting body, they are difficult to change.
It’s important to realize that the price of offsets on the market is determined by supply and demand, rather than the program cost. BURN sells its carbon credits to different buyers at different prices, providing lower prices to corporate purchasers who buy in bulk. To ensure that it recoups the total cost of its offset-funded projects, this means that prices are higher on the website. However, the marketed price of the credit in this case is really not meaningful: what matters is the total amount of money spent. A buyer who spends $100 on low-priced credits vs one who spends $100 on high-priced credits are both contributing the same amount to the project.
As a result, our calculations show a discrepancy between BURN’s sale price and the actual cost per CO2e averted, meaning that per Giving Green’s analysis, each offset sold by BURN actually avoids more than 1 ton of CO2e.
We believe that BURN stoves are strongly linked to reduced GHG emissions and also improve the well-being of their owners. As with almost all offsets, we do not believe that an offset purchase can be viably linked to removing a specific amount of CO2, but we do believe that purchasing an offset enables BURN to distribute more stoves and directionally leads to fewer emissions.
You can purchase offsets directly from BURN here.
We thank Chris McKinney, Chief Commerce Officer of Burn Manufacturing, for a series of conversations that informed this document.
Berkouwer, Susanna B., and Joshua T. Dean. "Credit and attention in the adoption of profitable energy efficient technologies in Kenya." (2020).
Bhattacharya, Sribas, Albina, D.O. and Abdul Salam, P. “Emission factors of wood and charcoal-fired cookstoves.” (2002) Biomass and Bioenergy. 23. 453-469. 10.1016/S0961-9534(02)00072-7.