The two best solutions
The analyses show that the most climate and eco-friendly ways to exploit residual biomass are to use it either for the production of green fuels or for materials such as fertiliser or feed or building materials as insulation.
“Utilizing residual biomass for materials and green fuels looks promising. Material utilization also seems to be the cheapest option,” says Sara Shapiro-Bengtsen.
However, she stresses that this scenario has a certain degree of uncertainty, as it is based on fewer cases than the other scenarios because utilizing residual biomass for materials is not yet a very widespread solution.
“In the energy business, we often assume that residual biomass can be used for energy purposes, but the material scenario is so interesting that, based on this research, we recommend looking at new ways of utilizing residual biomass,” says Marie Münster.
However, it turns out that the most common way of handling residual biomass today, which is to incinerate it—either directly or after converting it to biogas—to produce heat and electricity, is a poor solution for both climate and the environment.
Professor Marie Münster elaborates on the results:
“The project indicates that it’s better if we try to utilize residual biomass for materials and green fuels first, before we use it for energy production such as electricity and heat. This confirms our theory that a waste hierarchy also applies to biomass, where it’s important to utilize the residual biomass repeatedly until we’re left with a final substance that can only be used for either energy production or in landfills.”
Surprising life cycle analysis
In the study, Sara Shapiro-Bengtsen has combined energy system analysis with life cycle assessments and resource assessments.
This sets the study apart from conventional studies of energy systems because it not only examines the harmful effects on the climate due to fossil carbon emissions, but also includes the effects of methane and nitrous oxide emissions. Furthermore, the study also examines other hazardous effects due to the release of microparticles and discharge of the nutrients phosphorus and nitrogen.
Microparticles can cause health problems, and nutrient discharge can lead to environmental and biodiversity problems due to oxygen depletion in lakes and marine areas.
By including other harmful effects and comparing the socio-economic costs they entail with the costs of the harmful effects on the climate, the researcher and her colleagues arrived at a surprising result:
“We can see that the way we handle residual biomass may have a greater negative impact on the environment than on the climate when we calculate the financial aspect of the damage. We expected the effects on the climate would be more dominant. This tells us that it’s extremely important that we in our analyses not only focus on the harmful effects on the climate—such as carbon emissions—but that we also look at other possible problematic effects. It’s necessary in order to be able to make the right decisions on how to handle residual biomass. Otherwise we risk choosing a climate-friendly approach that actually creates more expensive problems elsewhere,” says Marie Münster.
