Comparison between externally fired gas turbine and gasifier-gas turbine system for the olive oil industry D. Vera a , F. Jurado a, * , B. de Mena b , G. Schories b a Department of Electrical Engineering, EPS Linares, University of Jaén, Spain b Water, Energy and Landscape Management, ttz Bremerhaven, Germany article info Article history: Received 23 June 2011 Received in revised form 5 September 2011 Accepted 23 October 2011 Available online 16 November 2011 Keywords: Biomass gasification Gas turbine Electric efficiency Exergy abstract The olive oil industry generates during the extraction process several solid wastes as olive tree leaves and prunings, exhausted pomace and olive pits. These renewable wastes could be used for power and heat applications. The aim of this paper is to compare the performance of two small-scale CHP systems: a gasification- gas turbine system and an EFGT (externally fired gas turbine system). For this reason, several parameters have been calculated: generated heat and power, electric and overall efficiencies, biomass consumption, exergy efficiency, optimum pressure ratio, etc. These systems provide 30 kW e and about 60kW th . Simulation results show that the electrical and overall efficiencies achieved in EFGT system (19.1% and 59.3%, respectively) are significantly higher than those obtained in the gasification plant (12.3% and 45.4%). The proposed CHP systems have been modeled using Cycle-Tempo Ò software. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Most countries along the Mediterranean Sea produce olive oil in varying quantities. Spain, Italy, and Greece represent more than three-fourths of the total olive oil output in the world. The largest producer, Spain, supplies about one-third of the olive oil globally. The olive oil produced in Spain is exported to nearly 100 countries [1]. Spain’s olive-mills use a process of two phases to eliminate olive grove residues (Fig. 1). The energetic use of biomass wastes offers a cheap and technically feasible option to contribute to reduction of the CO 2 emissions [1,2]. Olive trees and olive oil processing industry produce large amounts of by-products (Fig. 1): wood wastes, pits, pomace, OMWW, etc. Besides, the olive oil industry is defined by the polluting character of its residues, of which about 5.8 million tons are produced annually [2,3]. This poses serious problems to the olive mills, the costs for waste treatment are increased, especially in the case of small and medium ones. Against this situation, the proposing SME- AGs intend to take an integrated and more proactive approach to the problem. The vast amount of wood produced per tree and year and the polluting charge of olive mill waste can be taken as an advantage, it can, for instance, be used in a) gasification, b) anaerobic digestion, or c) directly combustion of by-products. For all these reasons, RESOLIVE aims achieving the following objectives, [2]: - To define the specific conditions for implementation of renewable energy solutions specific to the olive oil industry. To enable the producers and their associations more indepen- dence from centralized energy systems. - To build a prototype FBG-GT (30 kW e ) to demonstrate its performance using different olive industry wastes as fuel (leaves, prunings, pits). The prototype will be built during last year of the project, in an olive mill situated in Úbeda in the province of Jaén (Spain). - To increase the competitiveness of European olive industry: to reduce production costs in the olive oil sector, access to a new market (electricity production), increase employment in the sector by capacity building in state-of-the-art technologies and creation of new jobs in the operation of the proposed system, etc. In this paper, olive tree leaves and prunings have been tested. Proximate and ultimate analyses, HHV (high heating value), LHV (low heating value) are shown in the Table 1 . In the last two decades, gas turbines have experienced a very noticeable performance improvement. Gas turbines allow achieving significant advantages in comparison with steam power plants, in terms of efficiency, plant complexity, capital and oper- ating costs, water consumption, pollutant emissions, noise levels, etc. However, in order to avoid the damage of the main plant components, gas turbines need high quality fuels (natural gas or light liquid fuels). Thus, the use of wood biomass (as olive tree leaves and prunings and olive pits) in gas turbines requires a proper * Corresponding author. Tel.: þ34 953648518. E-mail address: fjurado@ujaen.es (F. Jurado). Contents lists available at SciVerse ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy 0360-5442/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2011.10.036 Energy 36 (2011) 6720e6730