As part of the European Union Funded MinWater CSP project, Waterleau and Fraunhofer Institute for Solar Energy Systems (ISE) have contributed to sustainable water utilization within Concentrated Solar Power (CSP ) projects , allowing users and constructors of new CSP parks to find even more sustainable and environmentally friendly plant designs. MinWaterCSP’s aim is to reduce cooling water consumption by up to 95% and mirror cleaning water consumption by up to 25 %. To get a clear picture of the needs, facts and figures, Waterleau did several study tours to CSP sites in EU and Morocco.
One of the research sites is the 20 MW Gemasolar Torresol Energy tower CSP plant close to Sevilla in Spain, a park designed and built by Sener Ingenieria and partners and partly subsidized by EU funds and operational since 2011. The research findings have been implemented in the development of the NOOR III project, a 150 MW CSP plant in Ourzazate Morocco, expected to be operational in 2017.
In the Sevilla plant, the 304,750 m³ total reflective area in the form of 2.650 heliostats concentrate the solar power towards a 140 m high tower with central receiver, through which a molten salt heat transfer fluid transfers the solar heat via heat exchangers towards a high pressure steam driving a steam turbine. The molten salt can be stored, extending the electricity production after sun set (24h).
To guarantee maximum power output, Ecilimp Termosalar provides mirror cleaning services using adapted mobile cleaning devices. The spray water however is not being reused and leaking away in the soil below the heliostats. Water is also needed to feed the heat exchanger and the steam turbine. Total daily water consumption is 100m³/h from which 90m³/h is used for cooling purposes. A rainwater storage lagoon containing 300.000m³ is filled up during the winter period provided the needs throughout the year. The rest water production is carried out with Reverse Osmosis (RO) treatment to produce demin water for boiler make-up water, mirror-cleaning water and other smaller demin-water users.
Waterleau has been analyzing water qualities and quantities needed for all critical steps in the CSP plant. With Torresol, Waterleau identified the perfect reference for the MinWater CSP concept (rainwater use, state of the art water treatment). Waterleau also researched solar driven alternative water solutions (membrane and multi-effect distillation). Concentrated Solar Power energy production has increased with an average of 50% during the latest 5 years with Spain and the US as largest energy producers. Morocco has committed to have 42% of installed electricity production from renewable sources by 2020, of which solar power will account for 14%.