Products, Utilisation and Impacts

Theme Leader: Dr Hu Li

This theme applies the fundamental information we gained from research under the Conversion theme to applied systems, in order to gain insights into practical problems, and develop approaches for reducing these problems. For example, ash behaviour in the boiler impacts on boiler performance, efficiency and plant availability.

Utilisation relates to boilers, furnaces, turbines, engines and fuel cells. Biomass has significantly different properties to fossil-fuels when applied to power generation and engine technology. Biofuels have the potential to play an important role in sustainable transportation. Biodiesel is crucial in helping the road transport sector to achieve its carbon reduction target. However, the production of biodiesel involves transesterification processes which consume energy and emit CO2. Direct use of straight vegetable oils can avoid this process and achieve bigger carbon reductions. Sustainable alternative aviation fuels such as biofuels are also explored in this area. The high sulphur content of conventional jet fuels is not only harmful to the environment but it is also bad for the materials in the hot zone of aero gas turbine engines. Replacing conventional jet fuels, with very low sulphur biofuels would largely eliminate or greatly reduce both problems. Some of the research into fuel cells lies at the boundary between biology and engineering, for instance that of biofuel cells and microbial fuel cells. In microbial fuel cells, bacteria are coupled to conducting surfaces and electrical energy is created by the bacteria growing on organic fuel sources, such as those found in waste water. Biofuel cells use a bio-catalyst rather than the complete organism and generally create energy from purer fuel sources such as hydrogen or glucose. There is interest in using biofuel cells for specialised functions e.g. powering medical devices within the human body.

Emissions during conversion are also explored in this theme, looking at the impact on air quality of burning biomass e.g. from domestic wood-burners or large power stations. A range of government initiatives currently aim to tackle climate change through encouraging the uptake of biomass combustion as a source of heat or combined heat and power at the district scale. Half of the world’s population rely on bioenergy, e.g. wood and charcoal, for their basic energy requirements. The combustion of these biofuels in open fires and traditional cookstoves emits smoke into the household, resulting in poor indoor air quality and the premature deaths of 3 million people annually (more than from malaria or unclean water). Installation of fuel efficient and clean burning cookstoves across the developing world has been proposed to reduce smoke emissions and improve indoor air quality. However, public and private sector action is hindered by poor understanding of smoke emissions and air quality impacts. This area also explores atmospherics. Combustion particulates (aerosol) influence cloud properties, but the impact of our changing energy consumption on clouds has not yet been explored and the role particles play in forming ice in clouds needs to be explored further. Aviation and other transport emissions as well as waste water are looked at in this theme. Bioenergy with Carbon Capture and Storage is explored as a means of achieving negative net emissions of CO2 while providing heat and power for human uses. CO2 Capture and Utilisation is an additional challenge.

Bio-products, bio-materials and co-products relates to biomass such as macroalgae (seaweed) which have applications in a wide variety of processes, in many cases offering the opportunity to replace petrochemically-derived products with renewable alternatives, which give comparable if not better performance. Importantly, macroalgae do not compete with land for food, and yet are a valuable crop, can be farmed and harvested throughout most of the year, and can even be grown utilising CO2 from carbon capture processes. Potential applications are very varied, from high value uses such as medical and cosmetic products, to large scale applications more closely related to bioenergy and combustion.