a b s t r a c tRapeseed is widely used to produce biodiesel, especially in Europe. In several studies, it has been shown that there is a good potential for growing this crop across the continent. However there is still little awareness that the energy efficiency of biofuel production from rapeseed is very low. Energy efficiency can be expressed in terms of Energy Return for Energy Invested (EROEI). We mapped EROEI values for all EU countries plus Switzerland based on expected yields derived from rapeseed suitability maps. We find that EU countries produce rapeseed biofuel with EROEI values of 2.2 and lower. We suggest that plans for biofuel cropping have to be supplemented by maps of EROEI. It is not only relevant to show where rapeseed can be grown, but we should also look at where its use for bioenergy can be efficient. In the area theoretically suitable for growing rainfed rapeseed (excluding unsuitable areas and water), 37.6% of the area can produce rape methyl ester (RME) biofuel only with an energy loss. We conclude that the energy efficiency of rapeseed biodiesel is low and spatially heterogeneous, and unless there are major technological improvements in the production process, replacing fossil fuels by biofuels from rapeseed is hardly a feasible option.

a b s t r a c tThe Netherlands, like other European Union countries, is under intense pressure to increase its national share of energy from renewable sources in accordance with 2020 Kyoto Protocol obligations. Bioenergy in this context is especially interesting because it can replace liquid fuels so much in demand for transportation. In Europe, due to high population density, and intensive use of limited land resources, sources of biomass are quite limited. This study examines the potential of road verge for biomass production. In this case there is no conflict with agricultural production e "food for fuel" conflict e and very little problems with natural conservation, since we are focusing on already disturbed and heavily used and polluted areas. The road verge is also easily accessible and in most cases already has to be maintained and cultivated. We use GIS (Geographical information system) to identify the total area of land along the roads in the Netherlands that can potentially be used for bioenergy purposes. We then consider the opportunities and constraints of cultivating various types of biomass, mainly focusing on grasses and willow, short rotation coppice, as biomass sources on the road verge. Based on that, we distinguish between areas that are unavailable due to safety requirements, areas that are conditionally available provided that current regulations are revised and areas that are already unconditionally available. We assess the entire production chain in terms of Energy Return on Energy Invested (EROEI), and consider various combinations of grass and willow operations for bioenergy production. Looking at several roads in Eastern Overijssel, we have estimated that there is approximately 4.24e4.68 ha/km of road verge conditionally available along highways, A-roads, and some 0.80e2.67 ha/km available along local roads, N-roads. However, only 1.02e1.62 ha/km and 0.37e0.80 ha/km of A and N roads respectively are available unconditionally. The EROEI for some scenarios of both grass-based and willow-based production were quite high, 15e42, making such use of road verge quite promising.

The production of bioenergy is dependent on the supply of biomass. Biomass production for bioenergy may cause large land use conversions, impact agricultural production, food prices, forest conservation, etc. The best solution is to use biomass that does not have agricultural or ecological value. Some of such unconventional sources of biomass are found within urban spaces. We employed Geographic Information System (GIS) and quantitative Life Cycle Assessment (LCA) methodologies to identify and estimate bioenergy potential of green roofs and other bioenergy options within urban areas. Net Energy Gain (NEG) and Energy Return on Energy Invested (EROEI) were used as indicators to assess the bioenergy potential of urban spaces within the Overijssel province of the Netherlands as a case study. Data regarding suitable areas were geometrically extracted from available GIS datasets, and used to estimate the biomass/bioenergy potential of different species with different yields per hectare, growing under different environmental conditions. We found that potential net-energy gain from built-up areas can meet 0.6-7.7% of the 2030 renewable energy targets of the province without conflicting with socio-ecological concerns, while also improving human habitat.

Most sources of biomass are located in rural areas, and use of this biomass for bioenergy may be in conflict with agricultural and conservation purposes. This study applied Life Cycle Inventory (LCI) and Geographical Information System (GIS) tools to estimate the Net Energy Gain (NEG) and Energy Return on Energy Invested (EROEI) for different biomass/ bioenergy production activities in rural areas. The focus was on those activities that are least damaging or even socially, environmentally or economically beneficial. We considered bioenergy production from crop residues, manure, and grass in natural grasslands and surplus pasturelands. The feasibility and vulnerability of different sources was assessed within the context of existing policy constraints, and the potential contribution to the EU's bioenergy targets was evaluated. Taking the Overijssel province in the Netherlands as a case study, we showed that 66.01 PJ can be contributed from by-products, with an additional 3.34 TJ coming from more conventional pasturelands. The NEG from biogas can potentially take care of Overijssel's entire renewable energy target for the year 2030. When producing bioenergy from by-products, the EROEI is quite high (7e17), indicating that there is a big potential for by-products to provide energy without compromising the ecological or agricultural functions of the landscapes. However there are still many changes in the practices, technologies and policies associated with bioenergy production that have to be made to harvest this potential energy resource.