Integration of a Geothermal Plant in a System with High Renewable Energy Penetration for Desalination Plant Self-Consumption

Abstract

The scarcity of water resources on the island of Gran Canaria (Canary Islands, Spain) is such that 88% of the water supply for human consumption comes from seawater desalination plants. This type of process has a high specific energy consumption. Gran Canaria has an isolated electrical system of low robustness. In this paper, a geothermal plant is designed and integrated into a system that already has non-dispatchable renewable generation (wind and photovoltaic) in order to meet, based on a self-consumption regime, the energy demand of a high-capacity desalination plant. The aim is for the diversified renewable system to improve the stability and management of renewable electrical energy generation. Geothermal plant production can adapt to the energy balance between demand and non-dispatchable renewable generation. The geothermal plant’s design is based on an organic Rankine cycle and its resulting power is 4.16 MW. Its integration in the renewable generation system significantly improves the contribution of renewables in meeting the desalination plant’s energy demand and therefore reducing its dependency on the island’s electrical system. The mean cost of electrical energy generation with the diversified renewable system is 57.37 EUR/MWh, considerably lower than the mean cost of conventional generation on Gran Canaria of 153.9 EUR/MWh.

Low enthalpy geothermal source for sustainable energy production in small islands: a real case study

“…Among renewables, geothermal has the advantages of being reliable, programmable, independent on climatic conditions and long-lasting and may be frequently available in small islands of volcanic origin [3]. Indeed, many works in the literature propose to employ geothermal resource for energy supply [4,5] and eventually for other processes, i.e. seawater desalination for freshwater production [6][7][8], sewage sludge drying [9].…”

Energy capacity of the geothermal resource and its integration in the electrical energy demand of the island of Tenerife (Spain)

“…In this way, the island's electrical energy system would benefit from the numerous strengths of this renewable and dispatchable energy source. These strengths include the lower levelized cost of energy compared to conventional electrical generation in Canary Islands [12], as well as it being considered a clean energy source in view of its low levels of CO2 emission per unit of energy generated [13]. In addition, geothermal energy has the lowest ratio between unit of occupied area and unit of energy generated of all energy sources [11].…”