Clean Cookstoves

Clean Cookstoves

Project Drawdown defines clean cookstoves as: solar-powered or fuel-burning household stoves that reduce greenhouse gas emissions by either increasing thermal efficiency, reducing specific emissions, or increasing ventilation. This solution replaces traditional cookstoves that burn wood and/or biomass inefficiently and without ventilation.

Currently, about a third of world’s population depends on solid fuels, including fuelwood and crop residue, for cooking. This is projected to increase by 8 percent by the year 2030. These traditional cooking practices impact not only global carbon dioxide-equivalent emissions from fuel combustion, but also the health of rural populations of the developing world due to household air pollution. Traditional stoves can be improved in three different ways, as named above. The type of cookstove is determined by the International Organization for Standardization tier based on thermal efficiency and emissions. Tiers 0 and 1 constitute the basic, traditional, solid-fuel-based stoves. Tiers 2-4 are considered improved clean cookstoves. [1]

This analysis evaluates the growth of improved clean cookstoves as a replacement for traditional cookstoves around the world. [2]

Methodology

Total Addressable Market [3]

The total addressable market is defined as the total terawatt-hour therms used by traditional cookstoves from 2014-2050. From the literature review, assumptions were derived for population growth, average population per household, average household useful energy use for cooking per capita, a weighted average energy efficiency factor for stove and fuel type mix, and the percentage of the population using solid fuels. From these assumptions, markets for the following regions were calculated: Asia (sans Japan), Latin America, and the Middle East and Africa. These values, along with global data from the International Energy Agency (IEA, 2006 and 2012), were used to develop a composite global market for the period 2014-2050.

Current adoption [4] of clean cookstoves was estimated at 1.46 percent of global terawatt-hour therms of solid wood stove emissions in the regions selected for this analysis. This figure was derived, in part, from data provided by the Global Alliance for Clean Cookstoves, and from prognostications from other adoption data sources (excluding liquid petroleum gas).

Adoption Scenarios [5]

Impacts of increased adoption of clean cookstoves from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels.

Four sources were used to evaluate adoption prognostications (GACC, 2014). The available data in these sources is largely global, describing the number of improved clean cookstoves currently in use or planned for dissemination in the future. Another report, from the Renewable Energy Policy Network for the 21^st Century (REN21, 2015), also provides adoption data for various regions—specifically Africa, Latin America, and parts of Asia (sans Japan).

For clean cookstoves, three scenarios were developed:

• Plausible Scenario: a global adoption of 622 million improved clean cookstoves is calculated over the period 2020-2050, which would result in a mitigation of 15.81 gigatons of carbon dioxide-equivalent compared to the Reference Scenario.
• Drawdown Scenario: Optimal investment from government agencies is assumed, as is a significant increase in financial capacity directed to global NGOs distributing improved clean cookstoves. This results in the adoption of 944 million improved clean cookstoves by the year 2050.
• Optimum Scenario: Adoption plateaus at the same rate as the Drawdown Scenario.

Emissions Model

Emissions mitigation variables were based on 17 peer-reviewed sources and weighting, calculating an emission factor of 1.39 tons of carbon dioxide-equivalent per ton of fuel. These values in the literature already consider the efficiency factor of the stove; hence, there was no need for any conversion calculation.

In addition to carbon dioxide emissions, black carbon is also an important factor to consider for the clean cookstoves solution. There is wide consensus on the impact of black carbon, but its magnitude is still under study—mainly because of the impacts of other components emitted with it during open combustion, such as organic carbon. Organic carbon consists of scattering particles and aerosols that are considered to have a global cooling effect.

Financial Model

Financial variables (the costs of traditional and improved stoves) have largely been obtained from sources such as the World Bank (2010) and US EPA (2015). Weighting based on cooking fuel mix was applied to all the costs. The average first cost of a conventional stove was found to be US$2.05, whereas the average first cost of an improved clean cookstove was found to be US$41. [6] Operating cost data was less available. Most of the fuel wood required for traditional wood-burning stoves is not purchased but collected by women in rural parts of the developing world, so the cost of fuel is modeled as zero.

Integration [7]

Drawdown discounted possible integration interactions with other solutions that might affect clean cookstoves adoption, total addressable market, or emission variables, including methane digesters (small) and electricity grid extension.

Results

The total carbon dioxide-equivalent reductions that can be achieved from 2020-2050 in the Plausible Scenario are 15.81 gigatons at the rate of 860 million tons per year for the year 2050, with a cumulative first cost of US$82 billion to implement 622 million stoves by the year 2050. This translates to approximately $130 per stove disseminated, and net savings of US$184 billion by 2050 for all clean cookstoves. A paper by Bailis recently published in Nature Climate Change estimates that up to 161 million tons of carbon dioxide per year can be saved with the dissemination of 100 million improved clean cookstoves globally. The Plausible Scenario shows the optimistic adoption of 100 million clean cookstoves globally in 2019, with an annual reduction at that time of 121 million tons of carbon dioxide per year.

Both the Drawdown and Optimum Scenarios assume a 20 percent learning rate, which dramatically reduces the cost of adoption as production of clean cookstoves scales. The number of clean cookstoves adopted by 2050 is 944 million, with a mitigation impact of 24.32 gigatons of carbon dioxide-equivalent over the period 2020-2050.

Discussion

Clean cookstoves are an important solution to consider for drawdown. It should be noted that 17 percent of the world’s black carbon comes from biomass-based cooking, and reducing this value to almost zero by replacing solid fuel-burning stoves with renewable fuel stoves is a huge step towards drawdown. The source of solid-wood fuel is not considered in this model, but the nature of clean cookstoves enables solid fuel of size and density that could come from regenerative forest management and not subsistence clear-cutting.

In addition to climate impacts, the health impacts of this solution are significant. In India, it was estimated that the dissemination of 150 million clean cookstoves over 10 years could help avoid 2.2 million premature deaths due to household air pollution in the country, and that the reduction in health burden in 2020 (measured in lost healthy life years) would be equivalent to about half the total national cancer burden projected that year. The potential rebound effects of improved health outcome on fertility rates, consumption rates, and emissions are hard to predict and are not studied in the literature.