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Centre for Integrated Energy Research

Chemical Engineering Improves the Biomass Efficiency

Over the past 10 years there has been a massive expansion in biomass use for power generation. Research has been crucial in addressing the challenges of moving from coal to biomass.

What is the problem?

In the UK, electricity generation through biomass co-firing began in 2002 and grew to approximately 28 MWe by 2005. More recently there have been several strategic investments by the UK’s power generation industry to replace coal with biomass, driven by legal domestic targets in CO2 reduction and government incentives. Employing biomass will result in at least 70% reduction in green-house gas emissions compared to coal. Increasing incentives could “employ up to 18,000 jobs in the UK by 2020 in the biomass electricity sector alone” (Bioeconomy Consultants NNFCC, 2012).

Why do chemical engineers make a difference?

Researchers from the University of Leeds, led by Professor Jenny Jones, have worked with Drax to become the biggest renewable power generator in the UK. Drax now operates three fully biomass-converted units and the company has reduced its carbon emissions by 12M tonnes per year. The research is underpinned by four main areas of chemical engineering: fundamentals of biomass combustion; biomass supply and combustion of energy crops; impact of inorganics on combustion properties and ash behaviour; torrefaction of biomass and impact on biomass handling and combustion.

The research involves the characterisation of fuels used in industry for their thermal conversion behaviour and their predicted performance for different technologies. The work stems from the very fundamental to more applied chemical engineering studies of behaviour, at large scale utilisation. This includes milling behaviour and development and application of computational fluid dynamic (CFD) modelling of large boilers and furnaces. The work is significant because it enables control over the combustion characteristics of a biomass resource. It led to further development of industrially important work which linked this to impacts in efficiency versus deposition in boilers and furnaces.

A Knowledge Transfer Partnership explored global wood fuel markets under strict sustainability criteria and widened the fuel portfolio. This directly contributed to the overall strategy of Drax Group PLC by supporting the establishment of new supplies. It also helped to diversify the business away from the historic total reliance on fossil fuel supplies for power generation

How has this made an impact?

The move to biomass has required changes in policy and practice at nearly every stage in the energy cycle, from fuel procurement and logistics to handling (including milling), burner design, and firing and emission control strategies. Research from the University of Leeds underpins a number of technical challenges the industry has overcome and has also informed policy, in particular the development of energy roadmaps. These impacts occurred as a result of dissemination and direct beneficiary engagement via collaborative R&D, consultancy, CPD and expert advisory roles and capacity building.

One company that has benefitted from technical innovations in the fields of biomass combustion, boiler efficiency, plant operation and emissions is the UK’s largest electricity generator, Drax Power, who generate 7% of the country’s electricity. The conversion and upgrading of Drax Power Station to use biomass instead of coal has resulted in carbon reductions of over 80% compared to coal, making it the UK’s single largest source of renewable power (20% of renewable electricity in the UK in the first half of 2016). The conversion generated in excess of £430 million in GDP (2016 prices) and supported over 7,000 annual jobs. In addition, some £118 million in tax revenue (2016 prices) was generated over the six-year process.