Go to Forum Home General Board Biomass – A Burning Issue: 2017

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    • #31990

        This is a valuable older post that you may wish to review first: https://aecb.net/forum/index.php/topic,2866.0.html

        I sent round to a group of AECB peeps a New Scientist Article on the air pollution issues associated with wood stoves. It prompted an email discussion – which is a shame for sharing with a wider audience, so I am copying here and encouraging the debaters to move the debate to the forum.

        1st response: from Phil
        “I do not really have time to respond in full to this article but I find it typical of many scientific papers in that it takes a subject in isolation and makes judgements that look like they make sense while recommending alternatives that, when analysed, make much less sense

        Let’s start with fashion. As with our feckless acquisition and discarding of clothing and gadgets, woodburning stoves have become a fashion statement. Instead of improving insulation levels, air tightness and boiler efficiencies in their leaky homes, the great, uninformed masses are sticking these things in open fireplaces to produce heat in order to compensate for the prodigious energy consumption of their home

        Our award-winning, low energy home/office (it is a passive house but I am not allowed to call it that) has a room-sealed, woodburning boiler stove which is our only source of heat for space heating and hot water. We do not have access to mains gas but I do have access to scrap wood which is a bi-product of the new build and adaptation projects that I design and project manage as part of my business. Site visits for contract supervision are often combined with filling my estate car with scrap wood, broken pallets and offcuts from the skips

        Oil and gas are not renewable sources of energy and their extraction is intensely energy-hungry and very inefficient. Burning anything is going to produce toxins and some of them are going to be unpleasant and probably harmful. Wood is a renewable resource. Chopping down trees to make logs or wood pellets only makes sense if new trees are planted on a like-for-like basis. This is not happening in the UK

        Burning wood, virgin or scrap, will produce toxins and in towns and cities these toxins will present a health hazard if the fashion for burning wood becomes widespread. Given the mess involved in running a proper woodburning stove, the latest fashion is for stylish and expensive, gas-fired, woodburning, look-alike stoves which are incredibly inefficient in turning high-grade energy into low-grade heat

        Burning wood (or coal) in the countryside (off the gas grid) is a way of life. LPG and oil are expensive options for those who don’t make energy efficiency improvements to their home. Wood pellets look like a good option with the generous subsidies available but boiler efficiencies are poor at a domestic scale and most of the wood pellets are being shipped from Scandinavia so watch those pellet prices go up

        If I stop burning scrap wood from building sites and buy kiln-dried logs for my stove, what environmental gains are we making? The scrap wood is transported in diesel lorries to landfill and where is the energy coming from to kiln-dry my logs and deliver them to my house?

        Joined-up thinking is in short supply here. If those pointing out the danger of toxins from burning wood are still eating meat, using aircraft and filling their homes with un-worn clothes and obsolete gadgets made in Chinese sweat-shops, they need an environmental reality check

        I am certain that some of you will see this subject from a different angle so all comments are welcome.”

      • #39246

          2nd response: from Mark (and for the record I feel largely the same way as Mark so succinctly puts it, below)

          “I'm a humanist first and environmentalist second.

          People in airtight homes with filtered air and airtight woodburners may be comfortable and healthy, but the pollutants that drift into lower quality neighbouring houses appear to result in an equivalent to cancer causing passive smoking. …anyone fancy emphysema?

          Whether it is fashion or stupidity, I personally can't justify or endorse activities that impair health and wellbeing or shorten the lives of people – even if it is to the benefit of the environment.


          P.S. The global warming potential of biomass is often overlooked. As is the fact that Biomass is a Finite Resource. At a national/regional level sequestration is another factor that needs to be considered. Some good exploration/discussion of these issues:

        • #39247

          This is reminiscent of the discussion on the forum 9 years ago when the situation was slightly less certain and there hadn’t been a BMJ article. The apparent reality as I now see it is:

          The exhaust emissions from burning gaseous, liquid and solid fuels in various appliances differ, sometimes by many orders of magnitude. See the US Brookhaven National Laboratory research. In particular, particle emissions are usually orders of magnitude lower from gaseous fuel combustion than from use of liquid or solid fuels. Solid fuels are by far the most difficult to control, for obvious reasons, and usually need electrostatic precipitators or similar. These are practicable on a 500 MW steam turbine, less so on a small appliance.

          Not all exhaust emissions are equal. I’d rather breathe in, e.g. CO2 than SO2. I’d prefer normal rural air at say 5 μg/m3 to air containing 50 μg/m3 PM-2.5s.

          As per usual in this area, the US and Canada have set stricter PM-2.5 limits than the EU, https://en.wikipedia.org/wiki/Particulates. That may reflect a smaller number of diesel car interests, although all their lorry and bus diesel engines succeed in meeting stricter emissions limits than EU heavy vehicles.

          The science has since moved on another 9 years, or why would the BMJ publish the article that it did revealing that UK wood emissions considerably exceed diesel emissions?

          Everyone needs to regularly examine or review their own practices and not assume that medical or scientific papers on the health hazards of particle emissions are wrong or that small-scale combustion is 'harmless'. It's a contradiction to construct a relatively green rural building and fit an un-green fuel source.

          The alternative to burning wood is burning something with less toxic emissions. One has or will have quite a long choice, the fossil ones being:

          natural gas
          and even
          kerosene or light fuel oil.

          although bio- or renewable synthetic ones should be produced in future.

          The combustion of the cleaner fuels on the above list doesn’t pose serious direct health risks. Particles do. So don’t emit particles, other factors being equal. Ditto with visible soot, which is a GHG.

          BTW, landfills surrounded by clay and containing any organic waste may eventually produce methane, a clean fuel. I'm sure wood could be dealt with in far better ways but removing trace impurities from biogas and burning the methane in a controlled manner seems less bad than soot, trace CO, some NOx and PM 2.5s now.

        • #39248

            Very much related:

            Subsidies should end for many types of biomass, a new Chatham House report argues, because they are failing to help cut greenhouse gas emissions.


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