A sustainability assessment of utilising energy crops for heat and electricity generation in Turkey

Abstract

The share of bioenergy is expected to increase in the future, necessitating the use of various bio-based feedstock, including energy crops. This study sets out to determine life cycle environmental impacts and costs of heat and electricity generation from two potential energy crops in Turkey – poplar (Populus spp.) and Miscanthus (Mischantus x giganteus). Different bioenergy conversion pathways, comprising direct combustion (heat-only and combined heat and power (CHP)), gasification (CHP) and co-firing with lignite, are evaluated via life cycle assessment (LCA) and life cycle costing (LCC). LCA results show that CHP-combustion using poplar is a better option than the other conversion pathways considered. All bioenergy plants provide great reductions (>80 %) in global warming potential (GWP), fossil fuel depletion and human toxicity (non-cancer) in comparison with heat from natural gas and electricity from the grid. Furthermore, for both feedstocks, CHP systems have lower impacts in seven of 17 categories than the heat from natural gas and electricity from the grid. Overall, the environmental and economic profiles of poplar-based energy plants are better than those of Miscanthus. However, the latter is better for GWP if land use change is considered. The LCC range between $2.2–$11.2/MWhth and $10.6–$28.3/MWhe and all bioenergy plants (except the Miscanthus boiler) would pay back within their lifetime. Compared to the costs of current heat provision in Turkey bioheat is 64 % cheaper, while only direct combustion plants outperform the grid with a 14 % lower cost. If 20 % of fallow and degraded lands are used for Miscanthus, up to 73 Mt./yr (or 14 %) of GHG emissions could be avoided, in addition to saving $4.7 bn (or 37 %) in the fossil-fuel import costs. These findings can be used by energy companies and policy makers to enable a more sustainable transition to a bioeconomy in Turkey.