PROJECT DESCRIPTION
BACKGROUND
Climate change, ground and surface water contamination and population growth have contributed to an increase in the scarcity of water resources. Indeed, water scarcity impacts 40% of the world’s population, with 2 billion people living in countries experiencing high water stress.
It is moreover estimated that a 2°C increase in the global temperature will lead to a decline of the 30% of the rivers in southern Europe. This will have an impact on cooling water intake for industrial and energy production activities, irrigation water availability, critical environmental flow conditions and the potential for hydropower. Spain will be especially affected since almost 74% of its territory is susceptible to desertification.
Natural groundwater provides drinking water to at least 50% of the global population and accounts for 43% of all water used for irrigation. However, groundwater supplies are diminishing, with an estimated 20% of the world’s aquifers suffering from over-exploitation.
Alternative water sources, such as seawater after desalination, can relieve the pressure on the groundwater resources. Desalination separates mineral components from saline water. Reverse osmosis (RO) is the leading desalination technology globally due to its relative high efficiency. RO desalination plants can remove salts and other ions and molecules from the water, making it suitable for drinking and for agricultural/industrial use. However, the process is highly energy consuming, despite recent improvements, compared to the treatment of groundwater resources treatment. The production of a cubic metre of freshwater from seawater requires around 3.5 kWh of electrical energy. The daily energy consumption would therefore be more than 330 000 MWh based on a daily water production of 95 million m3 worldwide. This energy consumption generates 92 000 tonnes/day of CO2 emissions.
OBJECTIVES
LIFE INDESAL aims to demonstrate an innovative and circular desalination process that recovers energy and byproducts. The integrated process, which consists of a high-efficiency reverse osmosis (RO) system based on low-pressure multistage systems (LMS), will produce high-quality water from seawater for human consumption and for use in agriculture and industry. The renewable energy available in the salinity difference between the brines of the first and second pass of the LMS RO is recovered using reverse electrodialysis (RED) and converted to electricity, thus further decreasing the energy requirements of the process. The high-salinity RED effluent is treated by electrodialysis with bipolar membranes (EDBM), generating NaOH and HCl to be reused in the desalination process. The lower salinity effluent exiting the RED process is recirculated to the first pass, first stage RO, diluting the influent seawater and hence lowering the hydraulic pressure needed. In this way, the process further reduces energy requirements and allows high flux RO membranes to be implemented, which also requires less energy.
Specifically, the project aims to:
- Design, construct and operate a pilot unit applying three technologies – LMS RO, RED and EDBM;
- Decrease by 0.2 kWh/m3 the specific RO energy consumption of desalination by LMS (two shorter stages, two passes) compared to a conventional RO (one stage, two passes);
- Obtain up to 0.1 kWh/m3 of renewable energy from the saline gradient by RED, taking advantage of the brine effluents generated, thus reducing external energy consumption;
- Transform desalination brines into acid and alkaline solutions at a sufficient concentration (3.5M), satisfying the whole demand of the desalination pilot unit;
- Improve the RO cleaning strategy, leading to a 20% reduction in chemicals consumption and an extended membrane lifetime, thanks to the LMS configuration and its independent cleaning system per stage;
- Quantify the environmental and economic benefits of the proposed scheme versus the conventional RO desalination process via LCA and LCC analysis.
- Boost the replication and transferability of the project outcomes by developing and scaling up guidelines and market preparatory activities aligned with dissemination activities, considering the forecasts of desalination growth and other markets in which results could be applied;
- Leverage the impact of the project by engaging key stakeholders and improve knowledge and acceptance of desalination processes; and
- Promote a more sustainable approach towards a more environmentally friendly desalination process.
