By EuroScientist Editor
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07 Sep, 2023
Hydrogen fuel can be made from wood waste in a clean and cost-efficient way at heat and power plants – and its developers hope it could change the narrative around this sometimes-controversial solution. By Steve Gillman & Fintan Burke The costs of scaling up hydrogen power, along with the potential amount of energy and natural resources to produce it, have seen this fuel source face increased scrutiny as a solution against climate change. “The majority of our electricity and hydrogen is produced from fossil fuels. This, of course, is not sustainable as it contributes to climate change,” said Michael Bartlett, a founder of Phoenix Biopower, a company that turns natural waste into combustible gas, like hydrogen. As part of a research project called Bio-FlexGen, Bartlett is developing ‘green hydrogen’ from biomass waste from the forestry sector. “Our ultimate goal is to provide a secure, renewable and low-cost energy for society and industry,” he adds. Bio-FlexGen, and its multidisciplinary team of 14 partners from five EU countries, aim to provide the technology for combined heat and power plants (CHP) that can also generate a supply of green hydrogen in addition to usual outputs of electricity and heat. To make green hydrogen, Bio-FlexGen will use a combination of two main technologies – a gas turbine and a gasifier. First, waste biomass is added in a gasifier at pressure and heated up to 850 Celsius – a temperature so hot that it releases other gases, mainly hydrogen, methane, and carbon monoxide. The next step sees water and steam added to cool before it passes through a cleaning filter. “Once we have cleaned up the gases from the gasifier, we can either send it to the gas turbine for combustion and electricity generation or to a hydrogen production unit,” said Bartlett, adding that this process gives “enormous power” and efficiency to the CHP plant. The high temperatures of this process, over 1400 Celsius in the gas turbine combustor, also result in greater power generation. To ensure a high efficiency, the system is designed to gather waste heat and recycle it back into the gas turbine in the form of hot steam. This, Bartlett says, can result in double the electricity output that is typical for a given amount of biomass. The new approach means the CHP plant then has three modes of operation; 1/ produce heat and electricity efficiently from biomass in the winter 2/, produce green hydrogen and biogenic CO2 from biomass in the summer 3/ utilise hydrogen in the gas turbine for peak power. This flexibility means it can help keep costs low and stable and complements the hourly, weekly and seasonal variability of solar and wind power. Converting critics and pushing EU hydrogen plans ahead Bio-FlexGen’s systematic approach to incorporating green hydrogen could go a long way in negating the main arguments against this renewable energy, primarily the amount of natural resources it requires for its production. According to Rystad Energy, 620 million cubic meters of water are needed to produce 85% of the green hydrogen capacity planned for 2040. However, environmental groups like Greenpeace argue that renewable power alone is not enough to produce the needed amount of green hydrogen. If anything, they claim this may end up increasing fossil fuel demand. But Bio-FlexGen’s green hydrogen production utilises oxygen to drive the gasification process, itself a by-product of green hydrogen production from wind and solar power. “The main advantage of getting hydrogen from biomass compared to wind or solar is that it has less variability and is not dependent on electricity price,” said Bartlett. “It also requires less H2 storage (you store biomass instead) for when the wind doesn't blow.” When producing electricity from biomass in the CHP plant, a lot of steam is needed in the gas turbine for the best effect. In fact, 50% of the exhaust is just water vapour. This water is recovered, treated and recycled back to this process, and an excess of clean water can even be produced for other consumers. When this water is recovered, it also generates large amounts of heat, which the project can use further in district heating networks or other processes. In this way all the energy in the biomass is efficiently used. “We are working very hard to ensure that we are part of a circular biomass utilisation and that we are using hydrogen in the safest possible way,” explains Bartlett, adding that the project will make a “significant contribution to the decarbonisation of the energy system”. The first commercial plant using Bio-FlexGen’s approach is planned for 2030, in which the power plant will operate on biomass in the winter months and use 100% green hydrogen in the summer months, therefore displacing demand for fossil fuels in peak periods – a goal increasingly shared by EU policymakers. Following the war in Ukraine, and the embargo on Russian oil imports into the EU, the European Commission outlined a ‘Hydrogen Accelerator' concept to scale up renewable hydrogen deployment. This ‘REPowerEU Plan’ wants the EU to produce 10 million tonnes of renewable hydrogen by 2030, with the Commission recently proposing criteria that Member States can follow to ensure they produce green hydrogen, including that it only be produced when and where sufficient renewable energy is available. As BioFlexGen’s power plant will operate with up to 100% green hydrogen from solar and wind, with an optimised combination of bioenergy, it is already on course to meet these criteria. Bartlett also believes that the project has brought together “amazing, competent people” that can play a key role in developing green hydrogen further.