Fired Up: Wood vs. Natural Gas (vs. Rocket Stoves) for Environmental and Personal Health

Energy and heat are two key physical technologies (to be used on conjunction with social technologies) in moving from our dysfunctional status quo to a future of thriving on one planet’s worth of resources (one planet thriving). Increased resilience during the transition so that we can build that future is critical. Multiple solutions are necessary, including rocket stoves and rocket mass heaters, stirling enginesalcoholbiofuel, and more.

Our community is trying to decide whether to allow wood stoves in addition to the natural gas central HVAC systems our units have (but, if you are interested in heating with wood, you have to consider rocket stoves and/or rocket mass heaters instead of wood stoves. They burn cleaner, use 70-90% less wood, e.g., 1 cord of wood lasting 4 months, and you can watch the flame like a wood stove with particular designs). Of course, any time we spread our eggs to multiple baskets (in food, energy, etc.), we increase our resilience. If the power goes down, where do we get our heat? Not necessarily from our furnaces (although there are ways to run them with power backup solutions). So, having multiple sources of heat in our community increases our resilience.

However, some people in our community are concerned about health and environmental effects. Wood stoves produce fine particulate matter with local health impacts vs. natural gas which contributes to climate change and has health impacts related to the extraction site and methods of extraction (including particulate matter released during frack sand mining). This article by David Holmgren, co-originator of permaculture, covers these considerations quite well, with an emphasis on the issue of wood smoke’s effects on health. Also, see this letter from 2005 published by David Holmgren that discusses wood as a sustainable and appropriate source for heat.

Smoke from burning wood (through wood stoves, fireplaces, outdoor fire pits, etc.) is about 80-90% fine particulate matter (PM 2.5 = 2.5 microns in size or lower). Other activities that produce PM 2.5 are burning candles, using kerosene heaters, and smoking cigarettes. In short, there are health risks associated with fine particulate matter. See Chapter 6 in David Holmgren’s book, RetroSuburbia, for an excellent discussion of heating and cooking with wood that addresses the balance between health and environmental effects (spoiler alert: wood will be needed and can be done in a way that minimizes health effects) and also reviews different stove types and their pros and cons (another hint: for outdoor cooking, consider a metal drum cook stove (p. 116).

However, in our community with central HVAC, the use of filters can remove particles of 1 micron in size. Filters are rated for their efficiency in removing particles of this size, ranging from HEPA filters with a proven record of improving indoor air quality to others with less efficiency. The most effective, non-HEPA filters, are electrostatically charged filters. The filters are disposable and can be installed and removed simply by sliding them in and out of the existing filter slot. Our units also have Breeze RenewAire Energy Recovery Ventilation (ERV) systems and the air is filtered through the furnace (as described here).

How does wood burning compare with natural gas? The Moral Issue is Murky

Secondhand smoke is not a great model. It is tempting to use secondhand smoke as a model for deciding about wood stoves. The moral clarity of secondhand smoke derives from its simplicity: “your smoking causes me harm (and no benefits); If I restrict your smoking, it prevents the harm.” In other words, it’s secondhand smoke vs. no secondhand smoke. It’s also very easy to apply to wood stoves with the understanding that the source of the “smoking”, in this case, is burning in wood stoves. The fact that 25 states + Washington, D.C. are now cigarette smoke-free (source) suggests that millions of people find this moral formula compelling. In our community, such moral clarity might successfully kill a proposal (see this article on consensus decision-making).

However, the formula for wood stoves is different and lacks the moral clarity of secondhand smoke. The argument for wood vs. natural gas looks more like this: Secondhand smoke vs. another harmful practice — “your wood stove causes me harm in some ways (and some benefits) while the alternative also causes me harm in some ways (and some benefits); If I restrict your wood stove, it may or may not prevent net harm.” The table below shows benefits and harms for environmental and health effects in a simplified form (notice that the table is restricted to environmental and health effects but could be expanded to include other relevant topics like resilience or social benefits, etc). The table demonstrates the lack of moral clarity in making a decision between wood smoke and natural gas. The relevance for our community is that a block should have moral clarity and there is no clarity here. The rest of the post discusses many of these issues in further detail.

  Wood Stoves Natural Gas
Local Health Effects Yes No
Local Pollution Air No
State & National Health Effects No Yes
State & National Pollution No Air & water
Contributes to Climate change No Yes
Renewable/Sustainable Yes No

This article concludes that there is more local pollution (through particulate emissions) with wood burning and thus health effects compared to natural gas but that burning wood emits 3-10 times less greenhouse gases than natural gas. However, the article does not take into account the many deleterious health effects of natural gas extraction accomplished through hydraulic fracturing (aka “fracking”), covered here. It is estimated that the percentage of natural gas extracted through fracking will increase from 42% (2007) to 64% (2020), while the National Petroleum Council estimates that fracking will account for 60-80% of new natural gas wells in the United States. In February, 2016, Harvard scientists reported that methane emissions increased more than 30% from 2002 to 2014, emissions that are large enough to nullify the reductions in CO2 during the Obama administration (see “Global Warming’s Terrifying New Chemistry” in The Nation, March, 2016 issue). The same article notes evidence that rates of methane leakage in fracking are between 3.6 and 7.9% and that as little as 3% leakage may impact climate change more negatively than coal.

Beyond climate change concerns, there are concerns related to the chemicals used in fracking (largely an industrial secret), the fine particulates produced to mine sand used in fracking (source), water contamination, and even some evidence that the process causes earthquakes (source). There is also research looking at the entire life cycle of shale natural gas (for which fracking is used), suggesting that it contributes 20% more (and perhaps twice as much) to climate change than coal per unit of energy (NY Times Article, 2011; see this article comparing wood and natural gas; and another from Utah Sierra Club). However, in general, there is more information on wood smoke effects than natural gas health and environmental effects. Thus, there is a data asymmetry present: lots for wood stoves, not much for natural gas.

Furthermore, the type of wood stove one uses is important. Here’s a list of EPA-certified wood stoves and best burning practices can further reduce emissions from wood stoves. Also, pellet stoves are another alternative. They are very clean with many models emitting less than 1 gram of pollutants per hour, compared to 4.5 grams per hour for and EPA-certified wood stove (without a catalytic converter). There are some really bad wood stoves that manage to escape EPA regulation through various technical modifications (Thank you PH for this research!).

None of this takes into account the peripheral benefits a wood stove can provide in a house designed around the wood stove as a central element. These benefits include drying food and clothes, heating hot water, and cooking and baking (see above picture of wood stove and Ben Falk’s excellent book on Homesteading for an inspiring look at this synergistic setup).

Here are some thoughts, though, about using EPA-certified stoves and the issue of local versus non-local pollution (Thank you MK for these thoughts!).

A lot of the EPA approved and high efficiency wood burners have a bit of added electronics to adjust air flow, monitor temp, monitor the oxygen level, etc., the main controllable factors that effect your burning efficiency. Those electronics require energy, oil, and heavy metals to produce. The heavy metals require even more energy and oil to extract from the earth and refine. And those electronics in your stove require electricity to function so you are using electricity while burning your wood, albeit a very small amount of electricity, probably less than 50W. At the point of failure or disposal of the stove, if those electronics are not handled correctly (which most electronics are not), they end up in a land-fill somewhere and leach out those heavy metals into the ground water.

Second point is similar to the first. I strongly suggest NOT having a stove with a catalytic converter on the basis of the extreme amount of energy and oil required to extract and refine the heavy metals needed. Here’s a bit lengthy paper, but it has a few good plots and statistics about how much energy is consumed for the mining and refining of platinum, the main heavy metal used in catalytic converters.

Moving away from the wood burning and taking a tangent on a more generalized philosophy based on fundamental thermodynamics, you can decrease the entropy in a localized part of a system by doing work, but that ALWAYS leads to an increase in the total entropy of that system. You’re probably more familiar with the food chain example. It’s the same thermodynamics. The higher up you go on the food chain, the more energy per mass was used/consumed to grow/sustain that life and is therefore less efficient on an energy basis.

It’s just hard for me to accept an argument of preserving our immediate environment at probably a greater expense and threat to someone else’s environment that is conveniently far enough away from us that we can say we worry about, but not actually feel the need to take actions to stop supporting that destructive practice. There are things we can do locally to increase our efficiency, decrease pollution, etc., but at the end of the day, if those things are reliant upon modern technologies, electronics, heavy metals, plastics, etc., they require way more energy to produce and generally create a lot more pollution during production, than what is gained from them.

But I do understand the perspective of wanting to directly see a localized increase in efficiency and pollution standards in this community. I just hope we’re understanding the broader, indirect impacts of those actions.


(1) The moral issue is murky. Compared to heating with natural gas, burning wood has less of an impact on climate change, no impact on earthquakes, no mention of effects on groundwater contamination, and no creation of particulate matter due to mining sand. In terms of health effects, burning wood has more negative health effects at the burn location than natural gas, but may have fewer health effects overall.

(2) We probably need better methods of heating our homes than what’s obviously and currently available. Ideally, the fuel would be renewable, sequester (rather than contribute) greenhouse gases, burn clean, and not contribute to an oil-centric violent foreign policy. Is there such a thing? David Blume would argue that permaculture-derived alcohol meets all of those requirements as a fuel but may or may not be suitable for home-heating.

(3) Rocket stoves may represent that alternative mentioned in #2. See this post on rocket stoves for an introduction to these technologies.













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Love that technology! Why the heck aren’t we using this stuff more? We know it’s needed, better, more sustainable, but our culture is NOT adopting it. What’s up?! 

If you are one of the few people who care about the physical technologies highlighted here that can save our planet, we need you to start becoming better at the social technology too. Because if people like you can’t start talking to others, we’re going to have a hard time adopting these superior physical technologies or may do so too late. 

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9 thoughts on “Fired Up: Wood vs. Natural Gas (vs. Rocket Stoves) for Environmental and Personal Health”

  1. Pingback: Consensus: Balancing Action and Discernment | One Planet Thriving

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  3. A little too Late! What about wood used to heat water? Dirt Dirty! Indoor and Outdoor wood boilers are not EPA Certified and they affect the lives of millions! There are over a million out there!. Check this link to a PBS Video of 4 families from upstate NY. This is something Gov Cuomo is allowing to hurt families and children! It is Criminal! Where is the Outcry?


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  5. Burning wood for heat and cooking creates carbon dioxide and therefore causes global warming and deforestation
    How you can write orherwiSe shows you have no understanding of chemistry

    1. Yes, burning wood does release carbon dioxide and yes causes global warming. However, as I’m sure you know, trees sequester carbon for their lifetime. When we burn it, we’re burning the carbon sequestered during that lifetime. Thus, net contribution to global warming could be near zero. Of course this depends on planting what we burn and timing it correctly. If we are burning more trees than we plant and the maturation cycle is not honored, we will contribute to climate change. Like so many practices, the details are important. Also, your comment doesn’t address a more basic issue, namely that if we have to heat our homes, there are trade offs against natural gas. The article is attempting to detail some of those trade offs.

      Thanks for engaging in this dialog. If you have some knowledge to contribute regarding the chemistry, I’m sure people would value hearing about it.

  6. Pingback: Thriving on One Planet: The Big Picture | One Planet Thriving

  7. The mention of Rocket stoves is very brief. A Rocket Stove is for cooking and while it can use less fuel than an open fire, it is still not ideal because the pot cools many of the gasses before they are burned. However, as you are talking about heating, I think you mean Rocket Mass Heaters which are a different animal all together. As such I would encourage you to also research high mass masonry heaters in general. Some numbers in general that are helpful. both wood and gas burners have a flue and to make that flue safe the exhaust gas has to be above a certain temperature. In a wood burning appliance this about 16% of the total energy from burning the wood. As gas burns at a lower temperature to begin with, even more of the energy created by the burning of the fuel needs to be used to force the flue gas out. You do mention EPA wood stoves which often have very high efficiency ratings. First those rating are based on 100% being minus the 16% to get the flue gas safely out of the house. Secondly, the testing is done in a lab where the only important measure is efficiency. The temperature in the testing room is far beyond comfort for a human. When the same stove is used in a dwelling, it is normally run at about 10 to 20% and because the low, slow fire does not burn thing completely, any air cleaning mechanism (catalytic converter) is quickly used up and becomes non-effective early in life. At the same time the outside surface of the stove, even at the idle most people use, is quite hot. The higher the temperature a surface radiates at the better it penetrates insulation. Insulation is a heat resister and we know that potential (temperature) divided by resistance gives the flow of heat. A high mass heater, like a masonry or rocket mass heater is designed very differently. First they are designed to burn at maximum speed and for maximum completeness. they use short burns, typically 2 hours in a 24 hours period. The heat is first absorbed by the mass with two effects: A) the combustion chamber is kept very hot which allows a more complete burn and much lower particulate emissions (many of the fine particles are burned or vaporized) B) The surface temperature is much cooler and safer (hot to the touch, but not burning) and so has a decreased flow through the building’s insulating shell. Most high mass heaters include a heated bench which transfers heat directly to the occupants. Of course heating mass rather than air has it’s own benefits.

    Central heating with it’s long ducts and harmful dusty air flow is very difficult measure efficiency with as a total system. Even though natural gas is only 60% the cost of electric power per energy unit, it still costs me less to heat my home with electric baseboards than with gas (which I removed a few years ago)… The wallet knows. Also remember that “Natural Gas” is not only Methane, but but includes a number of other harmful things.

    Heating with anything other than direct solar absorption, is a long study where you or I have just begun to scratch the surface. As with all studies, one has to follow the money to know who is funding that study and as such what is likely to have been left out of any published paper. Research costs money, those who spend that money do so to prove their widget is good and safe, not to find out if it is any good or if there might be something better.

    1. Great points, Len. Thanks for taking the time to share them. I’m not sure if you saw the post linked in this article. The post is about rocket stove and rocket mass heaters and does make that distinction clear, I hope. However, your points are a great addition. Thank you.

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