Biomass tops decentralised energy on emissions cuts

Decentralised generation, the distribution of energy generating sources so that power is closer to where it is needed, for example facilities designed to supply local communities, is likely to play an important part in future energy supply.

Belgian researchers have reviewed the operation and interaction of several different technologies, to assess their environmental impact. Using simulations modelled on generation units currently existing in Belgium, the findings suggest biomass could have the greatest impact on emissions reduction.

Belgium could theoretically reduce its CO2-equivalent emissions from energy generation by as much as 4% if it invests heavily and simultaneously in decentralised electricity generation technologies, according to new research. Researchers from the University of Leuven have used Belgian data to model the environmental impact of changes in the electricity production landscape, and calculated that biomass has the greatest potential to reduce CO2 emissions.

The authors created their energy simulations using PROMIX, a highly accurate model of current and future electricity generation units in Belgium. They considered six decentralised technologies: residential and tertiary (e.g. office buildings) combined heat and power facilities (CHP), biomass installations, wind turbines, photovoltaic units and hydropower installations. Belgium?s current power generation is based on nuclear, coal and gas.

The researchers used PROMIX to generate scenarios for 2012 as a means of assessing the potential impact of the different decentralised generation technologies on CO2 emissions. Within the PROMIX calculations they considered factors such as average hourly energy demand, the likely cost of fuel and the current technologies in place for power generation within Belgium. Large renewable and CHP facilities (over 50 MWe) were incorporated into the central power system for the purposes of this study which focused on the effects of increased use of decentralised technologies at the residential and community level. I

n terms of CO2 emissions, small, local biomass installations, if operated in CHP mode, appear to be the most promising technology for decentralised energy generation. Even the installation of units with a total production of 400MWe leads to a greater reduction in CO2 emissions than could be achieved by any other technology.

Unfortunately, the installation of biomass facilities requires resources, which may be beyond Belgium's reach. Where small, local wind turbine installations are concerned, overall emissions can be reduced when the total output of all installations is between 400 and 2000 MWe. The findings were similar for photovoltaic systems. The question remains as to whether it is technically and economically feasible to install sufficient wind and photovoltaic systems. The theoretical maximum power production for hydropower installations in Belgium is only 25 MWe, which is too little to have an impact on CO2 emissions.

The simulation also suggests that installing residential and tertiary combined heat and power (CHP) facilities will have little effect on the overall CO2-equivalent emissions from all energy generation sources. The study suggests that at the theoretical maximum capacity, residential and tertiary facilities would provide enough energy so that new, more efficient central power facilities would not be needed and less efficient facilities would continue in operation. This eliminates any positive effects of residential and tertiary facilities on CO2 emissions.

Source: Dries Haeseldonckx and William D’haeseleer (2008), “The environmental impact of decentralised generation in an overall system context”. Renewable and Sustainable Energy Reviews 12 (2) 437-454. Contact: [email protected]