Project Overview

AQUASOL Project was approved by the European Commission in 2001 and the activities have been initiated in March 2002. The project is divided in two phases: a research phase with a duration of 30 months and a demonstration phase with a duration of 18 months.

Main project objective is the development of an environmentally-friendly improved cost- and energy-efficient seawater desalination technology based on the Multi-Effect Distillation process.

Although everybody recognizes the strong potential of solar thermal energy to seawater desalination in arid and semi-arid regions due to the usual coincidence of water shortage, good solar radiation level and seawater availability, the process is not yet developed at commercial level. Main reason for this is that the existing technology although already demonstrated as technically feasible, can not presently compete, on produced water cost basis, with reverse osmosis technology. Nevertheless, there is still important room for improvement of MED systems based on solar thermal energy.

AQUASOL project is focused in the technological development of three main specific technological aspects that will significantly improve the present techno-economic efficiency of MED systems and therefore, reduce the cost of water production:

• Development of an improved Double Effect Absorption Heat Pump (DEAHP) optimized to the MED process to reduce the overall energy input needed. This device, if properly designed to recover part of the energy from the brine, can improve up to 100% the overall energy efficiency of the process and, therefore, to significantly increase the PR (Performance Ratio: kg. of distillate produced by 2,300 J heat input) of the system as consequence of the reduction of energy requirements.
• Reduce to zero any discharge from the process by recuperating the salt from the brine. This process will be accelerated by using advanced solar dryer systems specifically developed and designed to this issue. The elimination of the brine as wastewater will provide an important additional enhancement to the process economic figures, as the salt that can be obtained from each m3 of seawater is even more valuable than the water itself.
• Incorporation of solar energy to the process. Desalination is a clear example of process to which solar energy can be applied to cover its energy demand, due to the coupling of the disperse nature and availability of solar radiation with water demand supply requirements in many places around the world.

• Optimization of the thermodynamic cycle of a Double Effect Absorption Heat Pump (DEAHP) to reduce energy consumption in Multi-Effect Desalination plants (temperatures and pressures must be different from those used internationally in air conditioning).
• Determination of performance map for salt extraction from concentrated brine (brine air-drying): correlation between salt concentration, water, ambient temperature and air humidity.
• Assessment of exergy of solar radiation to the specific application of seawater desalination.

• Development of an optimized 200 kW DEAHP system to be coupled with MED plants to improve 100% the overall process efficiency.
• Development of a low-medium temperature static solar collector to drive the seawater desalination process. This system will be complemented with a gas fired backup system to guaranty to guaranty necessary operating conditions and permit 24-hours MED desalination plant operation.
• Development of an advanced solar dryer to accelerate the salt recuperation from concentrated brine, optimized to the output brine conditions.
• Development of a control system to the effective management of the overall process.

• Elimination of any brine discharge from MED plants.
• Effective incorporation of solar energy to the process, avoiding the use of other energy sources. It is expected that solar energy will provide a 30-50% of the total energy requirements.
• To increase the use of seawater, thus preserving scarce natural resources.