An example of theoretical carbon credit revenue in Mexico
Carbon credits, also known as carbon offsets, are a way to measure and trade reductions in greenhouse gas emissions. Fuel-efficient cookstove projects reduce greenhouse gas emissions from burning coal, charcoal, fuelwood, dung and other biomass fuels. The amount of reduced greenhouse gas emissions from fuel-efficient stove depends on both its combustion efficiency, and its usage frequency given the common practice of stove stacking, where households use a variety of stoves to accommodate different cooking practices. Furthermore, a fuel-efficient cookstove’s theoretical combustion efficiency, as measured in laboratory settings, can be higher than actual combustion efficiencies seen in development settings, due to imperfect usage of the stove, or wear and tear. This has led in recent years to appearances of project “greenwashing” and has lowered carbon credit values for fuel-efficient cookstove projects. Whereas fuel-efficient stoves generate less smoke and greenhouse gases than traditional three-stone fires, solar cookers are able to cook food without any fuel, generating zero smoke or greenhouse gases, and the risk of lower-than-advertised combustion efficiency is not applicable. Indeed, solar cookers’ ability to reduce greenhouse gases depends solely on their usage frequency.
In addition, solar panel and box cookers can be left unsupervised for hours at a time to solar cook foods slowly and evenly (like a crockpot), freeing women of the burden of chopping wood, tending to the fire, and stirring the pot to prevent burning the food. This allows women to engage in productive activities such as going on errands, attending to their children or gaining employment. These additional social benefits have earned some solar cooking projects “Gold Standard” certification, and higher carbon credit prices. Whereas most cookstove carbon credits typically sell for $5 to $10 per metric tonne of carbon dioxide equivalent, some with social benefits will garner up to $25 per metric tonne of carbon dioxide equivalent .
SHE does not currently manage any solar cooking projects certified for carbon credits, as the certification process is rigorous and expensive, making it cost-effective for projects upwards of 5000 solar cookers. We are in discussions with carbon brokers on the possibility of initiating such large-scale projects.
As an example of how carbon credits could support the spread of solar cooking, we examine the potential net revenue from the distribution of Haines Pop Open solar cookers in rural Mexico, where the predominant cooking method is the traditional wood-fired brasero, similar to a three-stone fire. Our studies show that solar cookers mainly replace the use of this “brasero,” used for cooking large slow-cooking dishes such as beans and rice, soups, and meat stews, dishes that are usually eaten at a late lunch around 2 pm. The gas stove is typically used sparingly for making coffee in the morning and heating up leftovers for dinner. This explains why participants typically report using their solar cookers 2 or 3 times per week but saving up to 50% of their fuelwood.
SHE’s baseline studies of cookstove usage in rural communities in Oaxaca, Mexico showed an average fuelwood consumption of 52 kg per week per household. SHE’s one-year pilot project evaluation showed an average usage of 3 times per week, and 47% of users claiming a dirty stove substitution rate of over 50% during the sunny season. Previous studies showed a usage decrease of less than half during the cloudy season.
SHE’s five-year evaluation of the “Solar Cooking Ambassador Program” in Oaxaca, Mexico, carried out in December 2022, found an average usage of 2.9 times per week for solar cookers that were 4 years old on average.
For this example study , we will use the very conservative estimates for our calculations of 30% savings in fuelwood over the whole year, a carbon credit price of $10, a Haines Pop Open cost (materials and shipping to Mexico) of $35 and lifetime of 4 years. That gives us a net revenue of:
Net revenue per solar cooker = (Annual fuelwood consumption/household (tonnes) x household fuelwood savings (%) x Emissions Factor for C02 for traditional unvented wood stove (IPCC value of 1.644) x carbon credit price (USD/tCo2) x Haines solar cooker lifetime (years)) – solar cooker cost (USD)
Net revenue per solar cooker = ( 2.7 tonnes/household x 30% x 1.644 x $10/tCO2 x 4 years) – 35 USD
Net revenue per solar cooker = 18.34 USD.
In other words, even with conservative estimates, carbon credits would cover the costs of Haines Pop Open solar cookers, and leave over 18 USD per solar cooker for distribution and training costs.
Factoring all project costs including training, monitoring and evaluation amounts to a cost of around 100 USD/solar cooker. A carbon credit price of US$19 t/CO2 would be needed to cover all project costs, or a carbon credit price of US$15 where users purchase the solar cooker for US$20. This does not cover certification costs.
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