Fuel from waste wood – Possibility to produce ethanol on a financially competitive and technically efficient basis

The researchers have also assessed the economic feasibility. “The prices we have calculated are based on assumptions for raw materials and energy. We are not using any current market prices. The calculation basis of our prices for the components in the chemical system is the year 2020,” explains Klüh. The lowest cost for ethanol in the modeling was 0.65 euros per liter, with biomass costs of 20 euros per megawatt hour, electricity costs of 45 euros per megawatt hour, and a production volume of approximately 42 kilotons of ethanol per year.

“With the current lignocellulosic ethanol production options, the costs are therefore competitive. The price of ethanol is very sensitive to the costs of electricity, and fluctuates between 0.56 and 0.74 euros per liter,” explains Assistant Professor Kristian Melin of LUT in Finland. One reason for the high profitability is that the ethanol yield is much higher compared to traditional fermentation based bioethanol process from straw or wood. This process produces 1350 to 1410 liters of ethanol, compared to only 200 to 300 liters of ethanol for the traditional process per dry ton of biomass.

Part of the study is focusing on the variable geographical positioning of production sites, which would enable a degree of independence from suppliers to be achieved. “Countries with a high potential for waste wood and green electricity, such as Finland or even Canada, can serve as producers of acetic acid, which, in the final process step, is hydrogenated to produce ethanol,” explains Prof. Tuomas Koiranen of LUT.

“In the future, countries like Germany will hopefully have a green electricity mix and will be able to carry out the hydrogenation of acetic acid to ethanol at a domestic level. However, Germany does not have the waste wood potential for a large-scale biomass gasification which is required for the synthesis of acetic acid,” adds Prof. Matthias Gaderer, Professor of Renewable Energy Systems at TUM.

With the use of green electricity to power the electrolysis, this process can produce a low CO₂ fuel that has a greenhouse gas reduction potential of 75 percent in comparison with a fossil fuel such as gasoline. Ethanol is established as a fuel. It can be used in the form of both E-10 gasoline, with 10 percent ethanol in the fuel mixture for regular automobiles, as is already the case, or as ED95, which is 95 percent ethanol, as a diesel substitute for heavy goods transportation.

With their process simulation, the scientists have demonstrated the competitiveness of the process. “To commercialize this product, it is necessary to further improve the degree of technological maturity. The next steps could entail further catalyst developments, a reactor design and the construction and operation of a pilot system,” says Prof. Gaderer.