The BTC plant

The BTC plant is a new, high efficiency biopower plant for power and heat generation. Through its integration of pressurized gasification with gas turbine combustion and massive steam injection, radically higher electrical efficiencies are achieved. The waste heat generated at 75 – 78°C is ideal for modern district heating grids and can, with a booster, be used to heat a carbon capture unit to separate carbon dioxide from the flue gases to generate negative emissions.

Key principles for BTC

• High-pressure gasification of biomass

• Combustion in a gas turbine for power generation

• Excess air in gas turbine replaced by steam

• Optimised heat integration

The BTC technology is based on an integrated process with steam as an efficient heat carrier and working media in the entire plant. Steam advantageously recovers energy from both the gas turbine exhaust and the gasification process and channels it back to the gas turbine. This steam, flowing through the combustor and expander, limits and distributes temperatures and removes the need for costly and energy-intensive compression of excess air in the gas turbine. Replacing excess air with steam and reducing need for compression energy represents an efficiency gain of 4-6%-points.

To recover the steam utilised, the water content in the exhaust gas is condensed. In contrast to the vast majority of power plants, this makes the BTC plant water self-sufficient, i.e., without the need for external make-up water. The heat generated while recuperating this condensate can be efficiently used for district heating systems, to drive a carbon capture unit (BECCS) for carbon negative power generation, biomass drying and other heat loads.

The heat from the gasification process is recycled in the gas turbine through the steam working as heat carrier. As the gas exiting from the gasifier at ~900°C, the gas is cooled using water and steam as partial quench cooling. This cooling step not only cools the syngas but also superheats the steam and carries the heat energy from the gasifier to the gas turbine where it is recycled in the high efficiency gas turbine to generate electricity. This integration represents 4-6%-points in electrical efficiency.