Biomass from agriculture in small-scale combined heat and power plants – A comparative life cycle assessment

• Published in: Biomass & bioenergy 2011-04, Vol.35 (4), p.1572-1581
• Main Authors: Kimming, M., Sundberg, C., Nordberg, Å., Baky, A., Bernesson, S., Norén, O., Hansson, P.-A.
• Format: Article
• Language: English
• Subjects: agricultural land; Agricultural Science; Air pollution caused by fuel industries; Applied sciences; Biogas; Biomass; CHP; combustion; Energy; Energy. Thermal use of fuels; Exact sciences and technology; food production; Fossil fuels; Fuel processing. Carbochemistry and petrochemistry; Fuels; Förnyelsebar bioenergi; Gasification; global warming; Green manure; greenhouse gas emissions; heat; Jordbruksvetenskap; Land; LCA; Life cycle assessment; Life cycle engineering; Metering. Control; Natural energy; Plants (organisms); Power plants; primary energy; Renewable Bioenergy Research; rural areas; Solid fuel processing (coal, coke, brown coal, peat, wood, etc.); straw; Willow; Willows
• ISSN: 0961-9534; 1873-2909; 1873-2909
• DOI: 10.1016/j.biombioe.2010.12.027

Biomass produced on farm land is a renewable fuel that can prove suitable for small-scale combined heat and power (CHP) plants in rural areas. However, it can still be questioned if biomass-based energy generation is a good environmental choice with regards to the impact on greenhouse gas emissions, and if there are negative consequences of using of agricultural land for other purposes than food production. In this study, a simplified life cycle assessment (LCA) was conducted over four scenarios for supply of the entire demand of power and heat of a rural village. Three of the scenarios are based on utilization of biomass in 100 kW (e) combined heat and power (CHP) systems and the fourth is based on fossil fuel in a large-scale plant. The biomass systems analyzed were based on 1) biogas production with ley as substrate and the biogas combusted in a microturbine, 2) gasification of willow chips and the product gas combusted in an IC-engine and 3) combustion of willow chips for a Stirling engine. The two first scenarios also require a straw boiler. The results show that the biomass-based scenarios reduce greenhouse gas emissions considerably compared to the scenario based on fossil fuel, but have higher acidifying emissions. Scenario 1 has by far the best performance with respect to global warming potential and the advantage of utilizing a byproduct and thus not occupying extra land. Scenario 2 and 3 require less primary energy and less fossil energy input than 1, but set-aside land for willow production must be available. The low electric efficiency of scenario 3 makes it an unsuitable option.