This paper explores the possibilities of sustainable biogas use for hybridisation of Concentrated Solar Power (HCSP) in Europe. The optimal system for the use of biogas from agricultural residues (manure and crop residues) in HCSP involves anaerobic digestion with upgrading of biogas to biomethane and injection into the gas grid for transport and storage. Using biogas from agricultural residues results in efficient reduction of non-renewable energy use and especially GHG emission, due to the avoidance of methane emission from manure storage. The net biomethane production from agricultural residues in EU-27 can potentially reach approximately 29,000 Mm3, sufficient to supply 320 CSP plants with a capacity of 100 MWe with HYSOL technology, producing 55% of the electricity from gas. The uncertainties concerning the production potential are large.

Farm nutrient management has been identified as one of the most important factors determining the economic and environmental performance of dairy cattle (Bos taurus) farming systems. Given the environmental problems associated with dairy farms, such as emissions of greenhouse gases (GHG), and the complex interaction between farm management, environment and genetics, there is a need to develop robust tools which enable scientists and policy makers to study all these interactions. This paper describes the development of a simple model called NUTGRANJA 2.0 to evaluate GHG emissions and nitrogen (N) and phosphorus (P) losses from dairy farms. NUTGRANJA 2.0 is an empirical mass-balance model developed in order to simulate the main transfers and flows of N and P through the different stages of the dairy farm management. A model sensitivity test was carried out to explore some of the sensitivities of the model in relation to the simulation of GHG and N emissions. This test indicated that both management (e.g. milk yield per cow, annual fertiliser N rate) and site-specific factors (e.g. % clover (Trifolium) in the sward, soil type, and % land slope) had a large effect on most of the model state variables studied (e.g. GHG and N losses).

Accounting for co-products of vegetable oil production is essential in reviewing the sustainability of biodiesel production, especially since oil crops produce valuable protein-rich co-products in different quantities and qualities. Two accounting methods, allocation on the basis of energy content and system expansion, are compared. Significant differences in results exist between the methods where system expansion is to be preferred because it can take actual use of co-products into account. Results are very sensitive to the choices made in system expansion. Differences can be large, especially between a system expansion where primarily the use of co-products of the oil crops is taken into account and an expansion that also includes direct oil exchange of the vegetable oil used for biodiesel for the marginal oil in the market.

Urine patches are an important nitrogen input source in managed pasture systems. The objective of this study was to quantify the effect of artificial urine application at different dates on nitrate leaching in a well drained sandy soil. In three subsequent years, we measured nitrate leaching and apparent urine-nitrogen recovery (ANR) in a field experiment and in two lysimeter experiments over a period of 1 year post urine application. Artificial urine patches with 400kgha−1of urine-N were applied at different times of the grazing seasons. For the field experiment, we compared nitrate leaching measurements with NURP model calculations. In the field experiment, greatest ANR was measured for spring and summer applications (averaging 31% of applied urine-N), and significantly declined to 0% for October applications. Nitrate leaching increased under urine patches, with a significant effect of application date. This effect was not, however, consistent over the three years. Total recovery of N in grass and of mineral N in leachate and soil was generally less than the amount of urine-N applied, with a balance deficit of 60-80% (field) or 10-70% (lysimeters). For the field experiment, the total increase in nitrate leaching corresponded reasonably well with NURP model calculations. However, the effect of application date on nitrate leaching was much smaller in the field experiment. Our results suggest that restrictions to grazing in autumn probably will be effective in decreasing the annual amount of nitrate leached, although this decrease remains hard to quantify.

This study focusses on the production of vegetable oil based products. A limited number of aspacts of the sustainability of the full chain (from agriculture to product at the factory gate) was evaluated. Three different vegetable oils were taken into account: palm oil, soy oil and rapeseed oil. Also three different products made from vegetable oil were evaluated: biodiesel, polyol (a raw material for production of PU foams) and resin. In the present study, sustainability of these products was evaluated through the following parameters: Non-Renewable Energy Usage (NREU) (GJ per ton of product); Greenhouse Gas (GHG) emissions (ton CO2-equivalent per ton of product); Land use (ha/ton vegetable oil) and NREU and GHG emission avoided (GJ or ton CO2-equivalent per hectare of land).

In a bio-based economy, chemicals, materials, biofuels, and other forms of energy will be produced from biomass. Pressure on agricultural land will thus increase, calling for highly efficient solutions in terms of land use, with minimal environmental impacts. In order to gain better insight into the available options and their trade-offs, this perspective studies the production of polylactic acid (PLA), bioethanol, and bio-based polyethylene (PE) from wheat, maize, sugarbeet, sugarcane, and Miscanthus. While in current agricultural practice some plants are harvested and used as whole crop (e. g. Miscanthus), for others only part of the plant is used, with the remainder being returned to the field (e. g. wheat straw). In order to obtain an understanding of the unused potential we assume as default case that all agricultural residues and processing co-products are used for energy purposes, thereby replacing non-renewable energy. We conclude that this agricultural practice would allow to substantially reduce non-renewable energy use (NREU). We also find a clear difference in ranking depending on whether we study (i) NREU per (metric) tonne of product or (ii) Avoided NREU per hectare of land. The latter seems a suitable choice in a world where land availability is limited. In this case, we identify PLA as the preferred choice, irrespective of the type of crop. The production of ethanol for the replacement of fuels scores as the worst option for all crops. For each of the products studied, sugarcane offers the highest savings per hectare followed by sugarbeet. (C) 2012 Society of Chemical Industry and John Wiley & Sons, Ltd

In deze studie is onderzocht hoe de duurzaamheid van verschillende biobased producten die uit fermenteerbare suikers kunnen worden gemaakt zich tot elkaar verhoudt. Daarbij is gekeken naar het gebruik van niet-hernieuwbare energie en de uitstoot van broeikasgassen tijdens het gehele productieproces, inclusief het telen van de gewassen. Er zijn vijf verschillende gewassen met elkaar vergeleken. In de studie zijn verschillende invalshoeken gekozen, waarbij in het ene geval er voor wordt gekozen de co-producten te verzamelen en om te zetten in energie, en in het andere geval de huidige landbouwpraktijk wordt aangenomen, waarbij co-producten deels op het land blijven liggen. Verder wordt het effect getoond van verschillende manieren om de data te presenteren. Drie manieren van presenteren leiden schijnbaar tot verschillende conclusies.

Resultaten van berekeningen van de effecten van teelt en verwerking van energiegewassen van vier verschillende ketens. De duurzaamheidsaspecten die aan bod komen zijn: vermindering fossiel energiegebruik en broeikasgas (BKG) emissie, behoud organische stof in de bodem, nitraatuitspoeling uit de bodem en gebruik niet-hernieuwbare fosfaatmeststof. Er is aangenomen dat de gewassen worden geteeld op akkerbouwbedrijven in Zuidoost Nederland, waarbij het energiegewas in de plaats komt van groene braak (=referentie landgebruik) op 10% van het totale bedrijfsareaal.