Biomass and Bioenergy 21 (2001) 335–349 The energy crop growth model SILVA: description and application to eucalyptus plantations in Nicaragua Richard van den Broek a ; ∗ , Leo Vleeshouwers b , Monique Hoogwijk a , Ad van Wijk c , Wim Turkenburg a a Department of Science, Technology and Society, Utrecht University, Padualaan 14, 3584 CH Utrecht, The Netherlands b Department of Theoretical Production Ecology, Wageningen University, P.O. Box 430, 6700 AK Wageningen, The Netherlands c ECOFYS, P.O. Box 8404, 3503 RK, Utrecht, The Netherlands Received 17 April 2000; received in revised form 8 May 2001; accepted 12 June 2001 Abstract Energy crop yield is an important parameter for the performance of a biomass energy system, both from a nancial and an environmental point of view. A crop growth model is a tool that can be used to estimate yields of energy crops in regions without present experience with these types of crops. This study describes the crop growth model SILVicultural Actual yield model (SILVA), which estimates potential and water-limited yield for a certain region on the basis of solar radiation and daily data for precipitation and pan-evaporation. With the help of already available commercial yields of the same energy crop at a reference location, it makes an estimate for the actual yield that can be expected. The model was applied on plantations of Eucalyptus camaldulensis established for electricity generation at the San Antonio sugar mill in Nicaragua. On the basis of the harvest results of about 10 tonne dm ha -1 yr -1 at the reference location, the Nicaraguan sugar mill Victoria de Julio, it was estimated that the E. camaldulensis plantation at San Antonio could produce about 13 tonne dm ha -1 yr -1 , mainly because precipitation was higher. The data requirement of the model matched well with data availability in Nicaragua. c  2001 Elsevier Science Ltd. All rights reserved. Keywords: Biomass; Eucalyptus; Nicaragua; Crop growth modelling; Sugar mill; Electricity generation; Energy crops; Yield 1. Introduction According to various long term energy scenario’s, dedicated energy crops may play an important role in the future energy supply [1–5]. This can be the case ∗ Corresponding author. ECOFYS, P.O. Box 8408, 3503 RK Utrecht, The Netherlands. Tel.: +31-30-2808-337; fax: +31-30-2808-301. E-mail address: r.vandenbroek@Ecofys.nl (R. van den Broek). especially in tropical countries, where land prices are often low and climatic growing conditions good. A parameter that can play a decisive role in cost assessments of biomass energy generation from en- ergy crops, is the yield of the crop [6–13]. Beside this, the yield also aects the environmental per- formance of the biomass energy system. This inu- ence can be both positive and negative. A higher yield will generally lead to lower fossil energy input and water and nutrient use per tonne of dry matter 0961-9534/01/$-see front matter c  2001 Elsevier Science Ltd. All rights reserved. PII:S0961-9534(01)00032-0