26 March 2024
Lydia Ren
Clean cookstove projects are seen as a key initiative for channelling funding toward addressing a major public health challenge. Today, approximately one-third of the global population, around 2.3 billion people, cook their meals by burning coal, firewood, and animal waste on open fires or traditional stoves (WHO 2022). The smoke from traditional cooking exposes them to respiratory and cardiovascular problems and leads to around 3.7 million premature deaths annually, with women and children disproportionately impacted (IEA 2023). Additionally, and importantly for the voluntary carbon market, this form of cooking releases roughly 2% of global greenhouse gas emissions and exacerbates deforestation and habitat loss due to the demand for timber, charcoal and other wood fuels (Bailis et al. 2015).
people, one third of the global population, cook by burning coal, firewood and animal waste
annual premature deaths are caused by the smoke from traditional cooking
of global greenhouse gas emissions are attributed to traditional cooking practices
The voluntary carbon market provides a means to efficiently finance solutions to household air pollution issues, with great success. A report from the Clean Cookstove Alliance highlights a 45-fold increase in finance secured for cookstove projects on the voluntary carbon market between 2017-2023. Clean cooking is one of the fastest-growing project types in the voluntary carbon market, currently accounting for 1,368 of all 8,777 projects (Berkeley Carbon Trading Project 2023). Carbon credit retirement for cookstove projects has tripled in the past five years, with retirements in 2023 hitting 13.4 million (Trove Research).
Figure 1: Credit retirement for cookstove projects. Source: Trove Research
However, cookstove projects have recently come under public scrutiny over credit quality. The latest wave of scepticism followed a UC Berkeley study published in the peer-reviewed journal Nature Sustainability. The Gill-Wiehl et al. (2024) study estimates that cookstove projects in the voluntary carbon market are on average 9.2 times over-credited. Media outlets have published articles citing the study, with The Guardian posting a headline that cookstove credits are “1,000% overstated”, and the Financial Times claiming cookstove credits are “largely worthless”. However, the study has been met with many counterarguments from major stakeholders in the market. Gold Standard, a major carbon credit registry, stated that the study did not find actual over-estimation. Other stakeholders raised methodological scrutiny, challenging the assumption that literature values are more accurate than data collected through the projects’ monitoring process.
Before making judgements, it is necessary to understand how these projects curb emissions. Clean cookstove projects achieve emissions reduction by tackling two issues: black carbon emissions and deforestation. Black carbon is the most strongly light-absorbing component of fine particulate matter (PM2.5) and has significant climate warming effects in the near-term (GEF 2015). Black carbon emissions are typically generated during the incomplete combustion of carbon-based fuels, such as wood, charcoal, coal, and kerosene. Improved cookstoves facilitate more efficient combustion than traditional cooking methods and therefore emit less black carbon. More efficient combustion or using alternative fuels also means less wood is required for cooking, thereby reducing the demand for timber and mitigating deforestation.
To calculate the emissions reduction of a cookstove project, current methodologies in the voluntary carbon market consider a few key metrics, such as adoption, usage, and stacking rates, fraction of non-renewable biomass (fNRB), fuel consumption, firewood-charcoal conversion rate, emission factors (EFs), and rebound rates. See the figures below for a breakdown of each of the key metrics used in the emissions reduction calculation.
These rates reflect how many new stoves distributed by the project are actually in use, how many meals are cooked in the new stoves, and if the recipients are using the new stoves alongside their traditional stoves.
Cookstove projects can achieve emissions reductions by reducing timber consumption. However, net reductions can only occur when the saved biomass is non-renewable. The fNRB parameter considers how much woody biomass is harvested beyond the regeneration rate of a given area.
This metric compares the usage of cooking fuel before and after the distribution of new stoves, thereby calculating fuel use savings.
This conversion rate quantifies how much firewood is required to yield the same energy content as a given weight of charcoal. In other words, it reflects how efficiently firewood can be converted to charcoal.
This metric is a coefficient that relates the amount of carbon dioxide emitted to the fuel used.
This rate reflects how many of the stoves recipients have increased their overall cooking energy consumption due to access to a new stove.
To assess the accuracy of emissions reductions calculations in cookstoves projects, the recent study by Gill-Wiehl et al. replaced the values used for these key metrics in the sampled projects with conservative values drawn from literature. The study found that the overestimation of the fraction of non-renewable biomass (fNRB) values was the largest source of over-crediting (1.7 times), followed by inaccurate firewood-charcoal conversion efficacy rates (1.5 times), with the adoption (1.4 times) and usage (1.4 times) rates of the cookstoves being jointly the third largest source of over-crediting.
Here is our take:
In short, while there is room for improvement at the methodology level, clean cooking projects are one of the worthiest causes to support with climate finance when done right, and so the best projects ought to continue to receive financing despite mounting media scrutiny surrounding the project type as a whole.
The cookstove debate underscores the necessity for well-rounded assessment, considering academic studies, industry practices, and evolving standards. We hope that as the dialogue continues, the market can engage with this discourse constructively to develop high-quality cookstove projects that can bring positive benefits to the communities and the environment.
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