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

For those who like to put things in context, read this short post covering the big picture of One Planet Thriving.

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 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.

Whole Systems Design: Woodstove

Source: http://www.permaculturevoices.com/tag/ben-falk/

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).

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.

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.

Conclusions:

(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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7 thoughts on “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. John Lichak

    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?

    http://video.wcny.org/video/2365195324/

    Reply
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  5. Bill deMis

    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

    Reply
    1. dmac Post author

      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.

      Reply
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