INTERNATIONAL research on how to make biomass energy production cleaner and more energy efficient has been led by the University of Hull.
A team of researchers from the University has examined how new pre-treatment methods for biomass wastes will improve the quality of renewable fuels of the future.
The research, which has been released as a scientific publication, found that by processing biomass wastes with low-energy ultrasound will help to optimise their properties, and cut down the harmful emissions being released into the atmosphere.
This is done by removing ash components which cause many operational problems inside reactors when working at the industrial scale.
It will also reduce the risk of corrosion or blockages occurring inside the bioenergy reactor, which often forces bioenergy plants to temporarily go offline while cleaning takes place.
Work of this kind is critical for industry big-hitters such as Drax Power Station in North Yorkshire, which has in recent years turned to biomass waste as an alternative to burning coal.
Dr Vasiliki Skoulou, Director of Research in Chemical Engineering at the University of Hull, the principle investigator on the project, said: “In order not to encounter operational problems when using biomass waste for energy, one method is to pre-treat residues before they are sent for energy production.
“This can be as simple as reducing the size of the grains, drying the waste or removing components all together.
“In this study, we looked at ways of enhancing a classical form of pre-treatment, water washing.
“Here, we used other technologies such as ultrasound and microwave at the same time to improve the process and reduce the energy required.
“Water washing is where the biomass waste is immersed in water and mixed, often at high temperatures.
“As the water enters the biomass, ash components are removed and dissolve into the water.
“This means that the water contains more minerals making it perfect for agricultural use, whereas the biomass waste loses problematic ash.”
Research found microwave and ultrasound are two technologies which can speed up the pre-treatment process.
To achieve the same result, water-washing required 24-hours, whereas microwave only needed four hours. However, ultrasound, using over 100 times less energy than microwave, only needed six minutes.
It makes ultrasound the best-known pre-treatment method of biomass fuels to date.
Dr Skoulou was one of five authors behind the new paper, titled ‘Augmented Leaching Pre-treatments for Forest Wood Waste and Their Effect on Ash Composition and the Lignocellulosic Network.’
Dr Skoulou’s research was kickstarted by a grant from the Engineering and Physical Sciences Research Council (EPSRC), as well as support from Energy Works Hull.
She was joined by Dr Martin Taylor, a Postdoctoral Research Associate and THYME Fellow at the University’s Energy & Environment Institute, and Hassan Alabdrabalameer, from the Department of Chemical Engineering.
Dr Taylor commented: “If ash builds up, the blockages stop fuel gas from getting through the reactor, which results in an operational shutdown to clean it all out.
“In business, time is money, so businesses want to avoid that at all costs. The ash forms colder regions in the reactor which cause tar to condense, this is a domino effect which leads to large expenditure for the company and as a result higher energy cost for the consumer.
“Ultrasound is already used at scale in many industries, whereas microwave technologies are not currently scale-up able. This makes this work readily applicable for the energy from waste sector.”
Other contributors to the paper were Dr Apostolos Michopoulos, of the University of Cyprus, and Dr Roberto Volpe, from Queen Mary University of London.
The project has also received support from THYME, a collaboration between the universities of York, Hull and Teesside, delivered in partnership with the Biorenewables Development Centre (BDC) and BioVale.
Funded by the Connecting Capabilities Fund of Research England, the £5 million project is focused on developing the bioeconomy across Yorkshire, the Humber and the Tees Valley, led by the University of York.
Dr Jenny Spear, THYME Programme Manager at the University of Hull, added: “Hull has a wealth of expertise in the pre-treatment of biomass for energy production.
“Through the THYME CCF project we are bringing together regional partners, to accelerate these technologies to improve the performance of local industry – producing greener energy.”