A cookstove production line at SSMNordica MacCarty

Tier 3 Biomass Stoves

/0 Comments/in , ,
Photo of sheet metal machines factory in China
Biomass cookstoves are mass produced at Shengzhou Stove Manufacturer

To reach multiple, interlinked Sustainable Development Goals, the UN advises that “the share of the population mainly using improved cooking solutions like low-emission biomass stoves reaching Tier 3* or better needs to increase to 35 percent by 2030.” (ACHIEVING UNIVERSAL ACCESS AND NET-ZERO EMISSIONS BY 2050: A Global Roadmap for Just and Inclusive Clean Cooking Transition, United Nations, 2023)

Well, that would be a very welcome change. The stove community has been trying to bring improved stoves into use for decades. Luckily, we are starting to know a lot more about how to improve stoves and increase market share: To make Tier 3 stoves successfully compete with traditional stoves. Much better stoves must be as loved by cooks while they make profit for factories, distributors, retailers, and, if lucky, for carbon developer and markets.

It may be that the most important missing link has been that, without carbon revenue, Tier 3 stoves have been too expensive. However, since the prices of avoided tons of CO2 have been fluctuating, a lot of folks have been exploring ways to sell Tier 3 biomass stoves without this subsidy.

Over the years, stakeholders (including the DOE, Shell Foundation, the European Union) have commented that substantial price reductions are possible by using less expensive materials, with design changes, more efficient production at scale, tariff reductions, decreases in the cost of transportation, and distribution with higher volume sales. As 2026 begins, the combination of factors seems to be bringing market driven Tier 3 (or even Tier 4) stoves closer to reality. 

Getting better products in use is occurring on a massive scale globally.

Let’s include good stoves.

*Biomass cookstove Tiers of Performance range from Tier 0 (worst) to Tier 5 (best). They are determined by using a standard test sequence (ISO 19867) that establishes international comparability in measurement of cookstove emissions and efficiency. Tiered Metrics include thermal efficiency, and levels of CO, CO2 and PM2.5.

Increased Air Exchange Rate Protects Health

/0 Comments/in ,

Sunken pot, 50% thermal efficiency cook stove with chimney

When (oh, when!) will PM2.5 be included in carbon offset methodologies? 

Who can blame stove manufacturers for selling high thermal efficiency/low combustion efficiency stoves when protecting health is not financially rewarded? 

Factories can only sell what the market demands even when they manufacture better stoves. Manufacturers, like SSM, already have slightly more expensive, much cleaner burning stoves ready to go. 

Including PM2.5 in carbon revenue might go a long way to help projects pay for higher combustion efficiency stoves.  

PM 2.5 needs to be reduced by ~ 90% to protect health in kitchens with 15 air exchanges per hour. The needed % reduction is halved when air exchange rates are doubled. This may be the most cost effective way to protect health? Cooking outdoors with an estimated 60 air exchange rates per hour is very effective in reducing exposure.When cooking inside, perhaps a durable stove with improved combustion efficiency and a chimney would help the large percentage of cooks who, for many reasons, continue to cook with biomass?

Clean Burning: Increased Carbon Revenue?

/0 Comments/in ,

Using the ISO testing protocols, Champion (2021)* reported energy emission factors (g/MJ) from the Three Stone Fire, a forced draft Pellet Stove, a forced draft Wood Fan stove, a natural draft Rocket stove and a charcoal stove. ARC added results from a Jet-Flame stove. Using the estimates of global warming potential from the Gold Standard 2017 Methodology** we started to develop a feeling for how various stoves might address climate change.

The calculations suggest that the Three Stone Fire could be a lot worse for climate when Black Carbon and short-term climate forcers are included in offset calculations. At the same time, forced draft stoves appear to have the potential to generate increased emissions reductions (and higher carbon revenues). 

*Champion, Wyatt M., et al. “Cookstove Emissions and Performance Evaluation Using a New ISO Protocol and Comparison of Results with Previous Test Protocols.” Environmental Science & Technology, 2021, 55, (22), 15333-15342. DOI: 10.1021/acs.est.1c03390

**https://globalgoals.goldstandard.org/standards/412_V1.1_ICS_SLCP_Black-Carbon-and-Co-emitted-Species-due-to-the-replacement-of-less-efficient-cookstoves-with-improved-efficiency-cookstoves.pdf

Fir trees and blue sky

Black and White Smoke

/0 Comments/in , ,
Fir trees and blue sky

Biomass: Captured sunlight

Wood burning cookstoves make smoke and many different gases that change climate. Carbon dioxide (CO2) is absorbed when the plant grows and the same amount of carbon dioxide can be released when that biomass is burned. So emissions of CO2 can be zero with no effect on global warming (carbon neutral) if the burned biomass is used at the same rate as it grows.

But other emissions from combustion are also bad for climate change. Generally, wood burning cookstoves do not make a lot of methane and carbon monoxide so these gases do not add a lot to their effect on climate change. 

On the other hand, biomass cookstoves without engineered forced draft can make a lot Black Carbon (the soot in smoke) and BC is very bad for climate change. For this reason, when protecting climate, cookstoves should make as little black smoke as possible. 

White smoke can have a cooling effect on climate. ARC has been learning how to make combustion chambers that emit as little smoke as possible and make 95% white smoke and 5% black smoke. We are working with manufacturers to make stoves with health/climate combustion chambers.

Short-lived Climate Forcers and Climate Change

/0 Comments/in ,
It is not difficult to estimate the emissions of Black Carbon from cook stoves.

The emissions that change climate include various gases and the colors of smoke. If the wood used for cooking is 100% renewably harvested, the emissions of CO2 can be carbon neutral. Why? CO2 is absorbed when the plant grows and the same amount of CO2 can be released when biomass is burned. 

100% renewability can help CO2 to become climate neutral. However, the fraction of non-renewability (fNRB) does not change the amounts of other climate forcing emissions. Smoke is smoke. Etc.

What are the most powerful cook stove emissions affecting climate?

In general, adding methane and carbon monoxide to Carbon dioxide (CO2) adds a bit to the total warming influences (CO2e). 

However, adding short-lived climate forcers such as NOx, SOx and Black Carbon to the above has been estimated to more than double the warming potential. 

For this reason, it seems to be important to add the short-lived climate forcers when calculating how to address climate change with cook stoves. 

red sign with white letters reading Wood Burning Prohibited

Clean Burning of Biomass

/0 Comments/in , , ,
red sign with white letters saying Wood Burning Prohibited

Scotland has banned the use of climate polluting home heating systems such as oil and gas boilers, and wood burning stoves (except in cases of need) in new construction. Heating homes creates one fifth of Scotland’s CO2e. The plan is to switch to electric heat pumps, hydrogen and tighter, better-insulated homes in an effort to achieve carbon neutrality by 2045. https://www.bbc.com/news/uk-scotland-68778757

Oil and gas (fossil fuel) burners create too much CO2. Burning renewably harvested biomass can emit close to zero CO2, but old stoves make too much black smoke which is ~2000 times worse for climate change compared to CO2 by weight.

Heating stoves that burn sustainable biomass cleanly enough to protect health and climate are starting to become available. Testing the new generation of stoves in use will show whether biomass can join solar, wind, and hydro as a useful renewable energy resource in the post fossil fuel era.

Maybe those red signs will become green?

Green sign saying Sure, Light Up
thermal image of house juxtaposed with daylight image of same house

COP 28: Near-zero emissions in global building sectors

/0 Comments/in , ,
thermal image of a house juxtaposed with daylight image of same house
Heat can constantly leak out of older homes. Photo: Gina Sanders

Aprovecho is investigating how to design and manufacture biomass-heating stoves that protect health and climate when burning renewably harvested biomass. Of course, staying warm depends on many factors including how much energy is being leaked from the building.

Net-zero buildings are usually tight and well insulated. A net-zero home can have a heating load of 10,000 to 15,000 Btuh (or ~3 to 4 kW) in a cold, northern climate. At COP 28, a minority of nations agreed to move towards net zero homes to reduce climate change by heating the better buildings with renewables. Green Building Advisor: 28 Countries Sign Buildings Breakthrough Agreement at COP28

Since the 1970’s, architects and engineers have learned how to dramatically reduce energy losses in buildings. Many net-zero homes take advantage of solar power to assist heating and create electricity. Solar gain helps a tight, well-insulated home to stay warm.

The United Nations found that buildings and construction account for 39% of total carbon emissions annually. Net Zero Homes: Your Guide to the Greenest Housing Option  If a new generation of very clean burning biomass heating stoves can protect health and climate, might they assist COP* countries to move towards near-zero emissions in global building sectors? *COP is the decision-making body of the UN Framework Convention on Climate Change.

Cleaner Burning Biomass Stoves: In Homes!

/0 Comments/in , , , , ,
https://i.pinimg.com/originals/0c/30/11/0c301121de2b7b0f6c4e07e360228e5e.jpg
The British Petroleum clean burning Oorja FD-TLUD stove from India

If protecting health and climate are important in stove projects, why not monetize the reductions of health/climate pollutants in carbon-offset projects?

Only the reduction in fuel use earns carbon income now!

With equal heat transfer efficiency, dirty burning stoves earn as much as clean burning stoves.

Dirty burning stoves are less expensive. “Market demand” reinforces the use of biomass stoves with low combustion efficiency.

Why not add income from reductions in CO, PM2.5 and Black Carbon, etc. to carbon projects to get cleaner burning stoves into use?

The approved 2017 Gold Standard Methodology already exists to do this! See: www.goldstandard.org/articles/black-carbon-and-other-short-lived-climate-pollutants

Moving Forward: Thanks to Jim Jetter’s EPA Lab!

/0 Comments/in , ,

Champion (2021) average energy emission factors (g/MJ) from ISO high, medium, and low tests. 

Champion, Wyatt M., et al. “Cookstove Emissions and Performance Evaluation Using a New ISO Protocol and Comparison of Results with Previous Test Protocols.” Environmental Science & Technology, 2021, 55, (22), 15333-15342.
DOI: 10.1021/acs.est.1c03390

Lab testing can quickly compare emissions from stoves. The EPA and ARC labs now measure the climate emission factors, not just PM2.5 and CO. It has been proven that only field tests show real world performance. Together, lab and field tests help to move stoves forward as we get closer to market driven stoves that please cooks, successfully cook food, use a lot less fuel, and protect health/climate.

The above chart contains a lot of information. Some takeaways are:

  1. Wow! The Three Stone Fire (TSF) was pretty bad! 943g/MJ for PM2.5, 15.5 g/MJ for CO.
  2. Charcoal made ~90% less PM2.5.
  3. The Carbon Monoxide (CO) from charcoal was only a bit higher than the Three Stone Fire (19.2g/MJ).
  4. LPG did so well! (Too bad that we are entering the end of the fossil fuel era).
  5. The forced draft pellet stove looked great, as well. (PM2.5: 30g/MJ, 2.2g/MJ CO)
  6. Black Carbon (EC) is much worse than CO2 for climate change. Many of the stoves, except the Rocket stove, successfully reduced Black Carbon. 
  7.  In this recent lab test, as in the previous MacCarthy study (2008), the Rocket stove emitted a lot of Black Carbon.  www.sciencedirect.com/science/article/abs/pii/S0973082608604299
  8. R&D has shown that the Rocket stove requires successful forced draft mixing at high temperatures to decrease emissions of Black Carbon and potentially address climate. 

When the emissions factors are summed and converted to global warming potential the forced draft stoves have the potential to generate large amounts of carbon offsets. 

Happy Holidays, 2023!

/0 Comments/in , ,
https://www.imf.org/wp-content/uploads/2018/03/BLOG-1024x600-Hand-holding-Plant-on-Soil-iStock-649090040.jpg

That the days are shorter is easy to attest to here at Blue Mountain. Our campus is wedged between parallel rows of 100-foot tall Fir trees. Yesterday, the rare sun fell down below the celestial horizon at 2PM.  We envy the valley farmers whose day lasts until around five. On the other hand, being surrounded by the forest up here makes the air sweet and clean. But only when the wood burning heating and cooking stoves that we are developing and testing are protecting health and climate.

It can be so terrible when traditional stoves are belching smoke! I have had pneumonia three times and get nervous when my throat gets sore. Clean burning makes me a lot happier. 

HEALTH: Can biomass be burned cleanly enough to protect air quality when warming houses and cooking food? 

CLIMATE: Can the Global Warming Potential of burned biomass meet the Paris Agreements and join solar, hydro and wind as a renewable energy source? 

Sure, we do both every day.  

Celebrating life and scientific endeavor in the forest becomes pleasant and comforting when we are toasty warm, and the smoke disappears. 

Feels downright civilized.