Is Bioenergy Really Sustainable?

We’re chatting bioenergy today. It’s got to be a good thing, right?
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Bioenergy is a renewable energy, derived from one of various sources of biomass. Biomass is organic material which comes from plants and animals. This material contains stored energy from the sun, so when it’s burned, it releases the energy as heat. Biomass can be burned directly for this heat creation, the heat can be used to then produce electricity, or the biomass could be converted to liquid or gas biofuels. A vast array of materials can be used as biomass, like wood and wood processing wastes, agricultural crops and waste, animal, food or yard waste and algae.
Bioenergy is a big topic with lots of subcategories. So we’re talking specifically about burning biomass for electricity creation today. And we’ll look at biofuels in an upcoming video.
In theory, if managed properly, growing and then burning biomass is circular and keeps the carbon cycle in check. Well, mostly. To make these calculations work the assumption is that the newly planted crops or trees begin absorbing CO2 at the same rate as was burned - instantly. Which, of course, isn’t the case. In fact, it’s been shown that trees absorb more carbon as they grow older because their speed of growth increases over time - so the longer a forest remains intact, the better.
Even putting those assumptions aside, issues arise when land management isn’t sustainable and more biomass is removed than grown. While the original idea might have been to use wood waste as biomass, often new forest timber is now being clear cut for this purpose. Animal agriculture has long been blamed for large scale deforestation and the resultant land erosion, and loss of habitat and biodiversity, but bioenergy is now also a threat. Two reasons for this is the need for increased volume of feedstock - wood waste just isn’t adequate; and the energy density produced not only varies based on type of feedstock but also on the shape and bulk density of it - for example, better energy output is obtained from solid wood than wood chips. BBC4 in the UK recently uncovered that large parts of Estonian forests are being felled specifically for the Drax energy plant in Hull, England. They’ve converted 4 of their 6 generating plants from coal fired to bioenergy. They mostly use pellets from sawmill residues, misshapen and diseased trees which can’t be used in other ways, or small trees removed to maximise forest growth density, but this simply isn’t enough. So biodiverse rich ecologically significant old forests in Estonia are now the second largest wood pellet producer in Europe.
There’s a link between land use, or clearing, and transportation. Moving feedstock which has higher bulk density is more efficient than transporting feedstock which has less - but it’s harder to come by. And the need for increasing volumes of feedstock obviously requires increased freight. The Drax plant takes in shipments of wood feedstock from the US and Canada (and as we know now, Estonia). Each ship will carry about 62,000 tons of wood, which requires 37 freight train journeys from the port to the plant, and will allow the plant to produce energy for just 2.5 days.
Burning biomass feedstocks actually results in the release of carbon dioxide, as well as various other harmful gases such as carbon monoxide, nitrogen oxides, and volatile organic compounds, which all contribute to air pollution. And there’s also pollution created from the use of the end products of biogas and biofuel, like ethanol. If ethanol is used in combustion engines it releases carbon and air pollution, just like petroleum fuels. But we’ll discuss that further in our upcoming video on biofuels.
Bioenergy crops include sugarcane, corn and soybean. The problems with this is that they are seasonal and they are food sources making way for the debate about land use for food Vs energy, because although the theory of using crop waste for energy is a good one, there is simply not enough to produce adequate biomass - farmers now grow crops purely for energy production. The price of crops will rise when they can be purchased to make biofuel for the Global North, making it more difficult for the Global South to feed its population with these staples.
There is never going to be an easy swap out of fossil fuels to an alternative energy source. But bioenergy does seem to be even more fraught, with a diminished return on investment, than most others. So our verdict: If managed well, bioenergy has a small place as part of a renewable energy mix. The key terms are ‘managed well’ and ‘small place’.

[@simondread]

Every day is a school day, another great informative video!

[@swrmTV]

Thanks so much for watching 💚🌎

[@davidonyemachi9254]

This was like a birthday gift to me.... 😁

[@swrmTV]

🎂🎉🥳

[@lianengineer4970]

Do Biogas please.. For me, I would like to promote using biogas, but most people in my country can’t afford or approach it.

[@swrmTV]

Will look into it 👍