Biomass is currently not in good shape as an option to contribute to climate goals. But in terms of CO2 emissions, biomass power plants are sometimes the least bad option for some types of fuel. This is evident from Steef Hanssen's dissertation.
'The debate about biomass has been killed,' says Steef Hanssen of the Environmental Sciences department. 'The consensus now seems to be: biomass is bad.'
And that's a shame, he says on the phone. Biomass can well contribute to achieving the Paris climate goals. And Hanssen should know. In recent years he has been working on a dissertation in which he meticulously compared the benefits of biomass energy with alternatives. Today he receives his PhD.
'Biomass is not just one technology, it is actually extremely diverse,' says Hanssen. 'You can burn pellets of residual wood, or specially grown biomass (such as grasses, ed.). The energy generated can also be used not only for electricity, but also to generate heat or make fuel. Writing it all off in advance is far too simplistic.'
Of course, cutting down trees in the Amazon to fuel power stations would be absurd. But for residual waste, a biomass plant can be more favorable in terms of CO2emissions than alternative processing methods, Hanssen states based on his dissertation.
Planks
To this end, he set up complex calculation models that calculate the CO for each alternative2emissions calculated. That had never been done before. 'Look at wood from a production forest. There are also trunks and branches that are not suitable for planks. The question is, what do you do with this, and what produces the lowest emissions?'
You can leave that residual wood, after which it rots away (a process in which CO2 is released). Alternatively, it is also often processed as paper pulp or in the form of chipboard (OSB) for construction. However, energy is consumed during all the transport and processing processes required for this - and therefore also carbon dioxide is emitted.
The third option, burning the wood in a biomass power plant, ultimately costs the least CO2, Hanssen calculated. This replaces a piece of CO2emissions from a fossil fuel power plant. Don't think that Hanssen is necessarily in favor of biomass, he emphasizes. If all energy were generated sustainably, the balance could turn out differently. 'But that is not yet the case.'
Underground
In another part of his dissertation, he calculated how much sense it makes to actively remove carbon dioxide from the air by planting special crops. After all, growing plants absorb CO2 on. Hanssen: 'You can then harvest and burn them for energy production, after which the released CO2 can be captured and put underground.' This way you kill two birds with one stone: net CO disappears2 from the atmosphere, while also generating electricity.
These types of methods (BECCS in technical jargon) are already being experimented with here and there, such as in the United Kingdom, but how much of a bottom line climate benefit they will deliver has never been precisely determined. Such a calculation can now be made correctly, thanks to a model that Hanssen developed for this purpose.
Coal plant
His conclusion: BECCS can contribute to achieving climate objectives, but you should not use it on a large scale. 'The land you use for this can no longer be used for anything else,' Hanssen explains. Moreover, preparing land for planting also leads to emissions. 'Only after thirty years does it produce a net removal of CO in some places2-from the atmosphere, but it usually takes longer.'
So it could work, that BECCS. But before you actively remove CO2 from the air, says Hanssen, it is better to stop pumping it in first. 'Otherwise you'll have to keep mopping with the tap open.'
Text: Stan van Pelt. This article previously appeared on biobasedeconomy.nl en Voxweb . Photos: Wikimedia Commons.
