Biomass – a problematic alternative

28 November 2022
How can we solve the problems phosphorus causes, when biomass is used as an alternative to fossil fuels (coal, oil, and gas) at power plants? Phosphorus is on the EU's lists of critical raw materials and it is a vital element for all life on earth. But it is problematic in several ways when it is present in considerable quantities in different biomass.

‘In power plants combusting phosphorus-rich biomass, corrosion caused by ash deposits, clogging of filters and deactivation of flue gas cleaning catalyst has been reported. Such problems can lead to frequent shutdowns, shorter lifetime of the equipment and increased emissions. Of course, the phosphorus emission is also a problem,’ says PhD student Emil Lidman Olsson from the Technical University of Denmark.

From power plant to laboratory
Emil Lidman Olsson has a background as a chemical engineer from Lund University, and he worked for among others Haldor Topsøe and Babcock & Wilcox Vølund before starting his PhD journey. In his research he draws on his experience from the power plants industry.
‘Even though people have burned biomass for 100,000 of years there is still so much research to pursue before we understand exactly what happens in all the chemical processes. That is really fascinating,’ says Emil Lidman Olsson.

His PhD project focuses on the phosphorus chemistry in thermal conversion of biomass. Beside the problems for the power plants and the emissions, an important long time perspective is to focus on how phosphorus can be recovered. Phosphorus is present in plant and animal cells and is vital to life on earth, and unlike oil and gas, which have alternative energy sources, you cannot replace phosphorus with another raw material or chemical.

PhD student Emil Lidman Olsson from the Technical University of Denmark (to the left) with some of the other award winners at the 24th Fluidized Bed Conversion Conference in Sweden.
Won Best Poster award at international conference
Earlier this year Emil Lidman Olsson won a best poster award, when he presented his work on a technology for fuel conversion at the 24th Fluidized Bed Conversion Conference in Sweden. In the technology, ‘oxygen carriers’ are used to transfer oxygen from air to the fuel, instead of exposing the fuel directly to air.

‘The benefit of the specific technology is that the flue gas will contain almost pure CO2. It makes it possible to capture the CO2 much more efficiently compared to capturing the CO2 from conventional power plants. If biomass is used in such a process, net negative CO2 emissions can be achieved, because the biomass takes up CO2 from the atmosphere, which can be captured in the chemical looping process,’ Emil Lidman Olsson says.

In his project he investigates how phosphorus affects a specific oxygen carrier.

‘If the process is to be scaled up, our results may help predict some of the challenges that may arise,’ he says.

Emil Lidman Olsson will defend his thesis in the beginning of 2023 and achieve a double PhD degree from the Technical University of Denmark and the University of the Chinese Academy of Sciences.