Zero emissions power

Bio-FlexGen: A major breakthrough for green hydrogen

Hydrogen makes up the largest part of our universe. The sun is mainly fueled by hydrogen. It is the first element in the periodic table. And it´s on the way to becoming a shooting star in its gasified form: green hydrogen. The EU-research project Bio-FlexGen generates and utilises green hydrogen from biomass.

Biomass provides firm power and complements renewable sources such as wind and sun when used in combined heat and power plants (CHP). Bio-FlexGen will increase the efficiency and flexibility of renewable CHP plants, playing a major role in energy system integration. This worldwide unique concept is called Biomass-Fired Top Cycle (BTC) and will be used for district heating and the energy system. 


Michael Bartlett, CTO Phoenix Biopower
©Phoenix Biopower

Michael Bartlett is part of this challenging journey towards a carbon-free Europe. An Australian in Sweden, he is Chief Technical Officer (CTO) of Bio-FlexGen’s engineering partner, Stockholm-based company Phoenix Biopower. Within Bio-FlexGen`s three-year lifecycle (until August 2024), it will tackle carbon-free biopower. Thus, it will improve security of supply by decreasing fossil imports from Russia or the Middle East. “Continued extreme events linked to the climate crisis, plus the energy shortages arising from the war in the Ukraine, mean that taking action is imperative. The flexibility of utilising or producing green hydrogen in different time scales is one of the core features of Bio-FlexGen. This helps achieve a stable and sustainable energy supply and is a very important contribution to the Green New Deal”, says Bartlett. Phoenix Biopower is currently commissioning a first prototype of the BTC plant and will be ready to offer commercial plants to the market in three years.

Highly efficient and extremely flexible

The novel BTC Bio-FlexGen technology will generate electricity at significantly higher efficiency – with a strong reliability and robustness. Bio-FlexGen engineers achieve this through a unique combination of a patented gasification and a patented gas turbine technology. Together, this allows the CHP plant to use green hydrogen for fast dispatch and biomass for low operating costs. Due to this high efficiency, nearly twice as much electrical power can be generated from the same amount of biomass. The plant quickly achieves full load by starting and operating on 100 percent hydrogen. It will also be able to mitigate fluctuations in seasonal demand and prices by providing climate-positive hydrogen production during long periods of low electricity prices and/or heat demand.

Different shades of hydrogen

This innovative Bio-FlexGen approach is a pressing matter. That’s because hydrogen accounts for less than two percent of Europe´s present energy consumption.[1] In general, there are various ways to produce hydrogen. They differ in their methods and carbon emission. Although hydrogen is an invisible gas, the industry uses various colours to differentiate between the types of hydrogen. Currently, the most common form of hydrogen production is called “grey”.  Grey hydrogen is produced from natural gas, or methane. It uses steam methane reforming, but does not capture greenhouse gases such as CO2 and methane. On a global level, around 98 percent of the generated hydrogen stems from fossil sources. That means: Almost all the hydrogen used today produces significant CO2 emissions.

Engineers working on the test rig
©Phoenix Biopower


Green hydrogen: Bio-FlexGen!

Bio-FlexGen generates 100 percent green hydrogen. Therefore, it uses a broad range of low value biomass, such as forest residues from sustainable forestry. The residues are pressurised in a sluice system and fed into the hot, pressured gasifier. Here, the solid biomass is converted to a gaseous fuel, some ash and char. Our Bio-FlexGen engineers master this process by pressurising and heating up the solid biomass in the gasifier together with steam and compressed air or oxygen. The outcome is a very diluted synthetic gas, called syngas. It mainly contains carbon monoxide, hydrocarbons, methane and green hydrogen.

It takes two…

The Bio-FlexGen plant currently allows for two modes of operation: In the first mode, the syngas from the biomass is generated with air from a gas turbine. Then it is filtered and combusted with more pressurised air in the same gas turbine. The gas reaches a temperature of over 1400 degrees Celsius at high pressure which drives the gas turbine expander with an enormous power. The second mode of operation generates a more concentrated syngas by using oxygen in the gasifier instead of air. In this mode, the hydrocarbons are also “reformed” and the carbon monoxide is “shifted” into a hydrogen-rich gas with a high content of carbon dioxide. Therefore, the BTC plant is a production unit for green hydrogen, while carbon dioxide can be capture and locked away at the same time. It can also flexibly switch between modes when the demand for electricity and hydrogen changes.

The hotter, the better!

The Bio-FlexGen gas turbine is really hot. It is a worldwide unique, and patented technology developed by the Phoenix Biopower engineers. It is called Biomass-Fired Top Cycle (BTC). Operating at temperatures of over 1400° Celsius, it has a higher efficiency than conventional boiler / steam plants. The hotter it is, the more power it can generate[1]. Thus, the plant can reach an efficiency of over 50 percent. By comparison, traditional CHP plants, which basically consist of a steam turbine cycle and a boiler, can only operate at up to 550° Celsius and have an efficiency usually limited to 25 -35 percent, depending on the size of the plant.

Cleaning the atmosphere

On top of it all, the Bio-FlexGen plant scores twice in terms of working towards a circular economy. With on-demand digital optimisation, it can generate four different products: electricity, heat, hydrogen and CO2 from biomass. As Michael Bartlett explains: “The biogenic CO2 is another key feature of the Bio-FlexGen plant. It can be used in industry applications to replace fossil CO2, like in chemistry and plastics industries. And when stored, it permanently locks away the CO2 that the trees of the biomass absorbed from the atmosphere while growing. This effectively removes carbon dioxide from the atmosphere and moves us back towards acceptable levels of atmospheric greenhouse gases”.

Whether green hydrogen will be a rising star in the energy sector is yet to be decided by European and international policy makers[1]. Within Bio-FlexGen however, green hydrogen from biomass is a star already: Making the Green Deal real!


The Phoenix Biopower facilities at KTH, Stockholm
© Phoenix Biopower 

 The Phoenix Biopower facilities at KTH, Stockholm
© European Science Communication Institute (ESCI)