Based on the R&D activity that Magtel is developing in the field of hybrid concepts in concentrating solar power plants, a paper with initial results will be integrated in the SolarPACES 2010 Conference that will be held in Perpignan, France, from September 21 to 24, 2010.
Next, you can find the extended abstract of the paper that will be presented:
SOLAR PARABOLIC TROUGH - BIOMASS HYBRID PLANTS:
A COST – EFFICIENT CONCEPT SUITABLE FOR PLACES IN LOW IRRADIATION CONDITIONS
Ángel Moreno Pérez1, Noel MesaTorres2
1 PhD in Industrial Engineering. Major: Energy System Optimization. Director. Magtel R&D
Address: Gabriel Ramos Bejarano, 114 – 14014 Córdoba, Spain. +34 957 429 060.
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2 Chemical Engineer. Major: Energy System Optimization. Senior Research. Magtel R&D
1. Objectives
This paper presents the technical and economical optimization of a 10 MW solar parabolic through - biomass hybrid power plant operating at an area in low average direct normal irradiation conditions but with plenty of biomass available. Solar thermal plants are usually installed in areas where annual accumulated value of normal direct irradiation is higher enough to ensure its profitability; this is the reason why most of the projects under promotion, construction or in operation are to be installed in the South of Spain an the Mediterranean and MENA areas. However, when combining properly a parabolic through with a biomass boiler, a substantial improvement in levelized cost of energy and thermodynamic efficiency could be achieved. As it will be proved by this paper, the generation cost and the thermodynamic efficiency are not independent variables, so that the physical behavior influences the economical behavior.
2. Background
Magtel R&D is currently carrying out an avenue of research aimed to setting up the basis for the optimized design of Solar Thermal Power Plants, and is receiving research fundings from the Spanish Ministry of Innovation and Technology under the so called Torres Quevedo Program (Project Reference PTQ-08-03- 06366), also being co-financed by Magtel R&D.
As a partial result of this research activity, assuming a location at the South of Spain in conditions of direct normal irradiation over 2.000 Wh/m2, the 50 MW solar parabolic through – biomass hybrid power designs achieved higher profitability rates (in terms of internal rates of return, IRR) and higher efficiencies than the conventional 50 MW - solar parabolic through power plants currently being installed in Spain. As a consequence of this, it could be raised the hypothesis that hybrid designs operating at areas in low irradiation conditions could produce at a COEL sufficiently high to meet profitability.
3. Methodology
A comparative analysis among three 10 MW technologies is going to be performed in this paper, under the assumption of being operating at the same location in the Rivera del Duero, a region located at north of Spain with plenty of vineyard areas. Irradiation data have been obtained from the Energy Plus data base for a location with coordinates N41,80º, W4,214º. The production of biomass from the vine production compensates for a moderate annual direct normal irradiation worth 1,961 Wh/m2. The technologies to be compared are parabolic – through solar thermal plant, parabolic – through solar thermal plant provided with thermal storage (in this paper, these technologies are going to be referred to as conventional technologies) and parabolic – through solar thermal biomass hybrid plant.
Thermodynamic and economic models for both the conventional and hybrid power plants have been developed [1, 2], and detailed process simulations of the systems has been carried out. The models have been adjusted, and reference states have been defined for both conventional and hybrid designs. The results of both thermodynamic and economic models have been used for sizing and budgeting the major plant sections. Numerous literature references and previous biomass and solar parabolic through thermal power plants were used to develop and to validate overall plant cost information [3]. The EPRI Revenue Requirement economic analysis has been performed to determine the levelized cost of electricity produced by each design.
4. Results
Given an installed power rate, it has been found out that the higher the thermal storage capacity, the higher the COEL, being the choice without thermal storage the best one. This trend has been graphically depictured in Fig. 1 for 10 MW installed power plants and storage capacities ranging from 1.000 MWht to 125 MWht and without thermal storage. This figure also shows that an optimum collector field size can be selected for any thermal storage capacity to produce electricity at a minimum value of COEL.
Fig. 1. Influence of the thermal storage capacityand hybridization over the COELfor different sizes of collector field
Fig. 2. Relationship between the economic and the physical behavior of the cases analyzed
It has also been found out that the COEL of the different cases analyzed in the optimum is directly linked to the efficiency performance: as shown on Fig.2, the higher the efficiency, the lower the COEL will be. Since the performance of the hybrid case is the most efficient, it has associated the lowest COEL.
Going back on the economic analysis (Fig. 1), the hybrid case has been found to be the best, with a minimum value of COEL=19.48 c€/kWh assuming actual market prices of biomass. This value is significantly lower than the best obtained for the choice without thermal storage, which value is COEL=30.60 c€/kWh. Based upon these results, a detailed financial analysis will be presented in this paper aimed to understand the economic feasibility of the hybrid plant in the selected location in comparison with the standard technologies.
References
[1] Price, H. (2003). A Parabolic Trough Solar Power Plant Simulation Model. National Renewable Energy Laboratory (NREL/CP-550-33209)
[2] Kelly, B; Kearney, D. (2004). Thermal Storage Commercial Plant Design Study for a 2-Tank Indirect Molten Salt System. National Renewable Energy Laboratory (NREL/SR-550-40166)
[3] Montes, M.J. et Al. (2009). Solar Multiple Optimization for a Solar-Only Thermal Power Plant using Oil as Heat Transfer Fluid in the Parabolic Through Collectors. Solar Energy 83 (2009) 2165 -2173. Elsevier.
