In March, Jesse Klaver (the leader of GroenLinks, the Dutch green party) was heavily criticised during a TV programme on the elections because his party had long supported biomass as a fuel for power plants in municipalities and provinces. “The debate about biomass has been beaten to death”, says Steef Hanssen of the Environmental Sciences department during a telephone interview. “The consensus now seems to be that biomass is bad. And that's a shame”.
In fact, biomass can help contribute to achieving the Paris climate goals. And Hanssen should know. In recent years he has been working on a PhD study in which he meticulously compared the benefits of biomass energy with various alternatives. On 31 March he defended his thesis.
“Biomass is not just a single technology, it is extremely diverse,” explains Hanssen. “For example, you can burn pellets made from residual wood or you can burn specially grown biomass (such as grasses, ed.). The energy can be used not only to generate electricity, but also for heat or to make other types of fuel. To write off all these possibilities in advance is very short-sighted.”
Of course, cutting down trees in the Amazon to fuel power plants would be absurd. Based on his study, Hanssen concluded that a biomass fueled power station – if it is fueled with residual waste – can actually be more favourable in terms of CO2 emissions than alternative waste processing methods.
Planks
For his study, he used complex models that calculated the CO2 emissions for each alternative. That had never been done before. “For example, if you 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 residual material, and which processing approach yields the lowest emissions?”
You can leave that residual wood lying around to decay, but this process generates CO2. Alternatively, it is often processed as paper pulp or made into chipboard (OSB) for construction. However, during all the transport and processing that is required for these alternatives, energy is consumed and CO2 is emitted.
The third option, burning the residual wood in a biomass plant, ultimately results in the lowest net CO2 emissions, Hanssen calculated. This type of biomass could therefore offset some of the CO2 emissions from a fossil fuel power plant. Hanssen emphasises that he is not necessarily a proponent of biomass. If all energy were being generated sustainably, the balance could turn out differently. “But that's not yet the case.”
Sequestered underground
In another part of his study, he calculated how sensible it is to actively remove carbon dioxide from the air by planting special crops. After all, such crops absorb CO2. Hansen: “You can then harvest the crop and burn it for energy production, after which the released CO2 is captured and sequestered underground.” In this this way you kill two birds with one stone: on balance, CO2 is removed from the atmosphere, while you also generate electricity.
Some experiments are already taking place with this approach (known as BECCS), in the UK and elsewhere, but the net climate benefit has never been accurately calculated. Such a calculation can now be made, thanks to a model that Hanssen developed for this purpose.
Coal-generated power
His conclusion: BECCS can contribute to achieving climate targets but should not be deployed on a large scale. “With this approach, you can no longer use the land for anything else,” explains Hanssen. Moreover, preparing the land for planting also leads to greenhouse gas emissions. “At some locations, BECCS provides net removal of CO2 from the atmosphere after 30 years, but it usually takes longer.”
So BECCS could work. But before you start actively removing CO2 from the air, Hanssen says, it's better to stop pumping it into the atmosphere first. “Otherwise, you'll just keep ‘mopping with the tap open’.”
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Text: Stan van Pelt. This article previously appeared on Voxweb. Photo: Wikimedia Commons.
