Drought, Italy also tries its hand at desalination.But there is no shortage of problems

More and more countries are at risk of extreme drought, including Italy.Desalination of sea water could be one of the solutions.

• Desalination is becoming more and more widespread around the world.Meanwhile, prices are falling.
• The technology must address two critical issues:energy consumption from fossil fuels and the environmental impacts of toxic brine.
• In Italy, a watermaker has been installed in Veneto, but the Salvamare law slows down the development of the technology.

Transforming seawater into drinking water.No, it's not magic.But, given the severity of the drought that is affecting northern Italy in recent months, the desalination (or desalination) could represent a small life jacket for those countries that are certainly not swimming in fresh water.The technology is now consolidated and widespread in different parts of the world but, between implementation costs, energy consumption and the production of toxic brine, some question marks remain.

Salt wedge emergency:a watermaker installed in Veneto

Reduction of soil fertility, damage to infrastructure and loss of fish crops.These are the devastating effects of the rise of salt wedge, which has now reached 30 kilometers from the Po river delta.The phenomenon occurs when salty sea water manages to make its way into the inland aquifer due to a reduced river flow.To buffer the drought emergency and the negative impacts of the salt wedge that are affecting the Polesine, a watermaker from Spain was installed in Taglio di Po (province of Rovigo).For a cost of around 150 thousand euros for two months' rent, it has the capacity to desalinate 100 thousand liters per hour, guaranteeing drinking water for five thousand people in the areas of Cutting of the Po and Ariano in the Polesine.

The watermaker is included in the solutions announced during a press conference by the water manager Acquevenete, the mayors of the Polesine municipalities, the Prefecture, the Arpav, the Ulss 5, the basin Council and the Province.Furthermore, some municipalities in the Lower Polesine have issued aorder for a rational, prudent and sustainable use of water.The provision prohibits the use of drinking water for domestic washing of cars and vehicles, courtyards and yards, filling of garden basins and ornamental fountains.

Desalination in the world:a growing trend

Desalination is based on a process called reverse osmosis, thanks to which water is forced through polymeric membranes that allow its molecules to pass while blocking salts and other inorganic impurities.With almost 16 thousand systems active or under construction, desalination is used in 183 countries;almost half of the total capacity is installed in the Middle East.In Europe, especially the Mediterranean countries are interested in technology which, in fact, has seen considerable development especially in Spain (as of 2021, approximately 765 systems have been installed).Among these, also large installations serving important urban areas, as in the case of Barcelona which, thanks to a hybrid system made up of two purification plants and two watermakers, manages to guarantee drinking water to 5 million inhabitants and more than 8 million tourists a year.

Bahamas, Maldives and Malta these are some of the countries that satisfy all of their water needs through the desalination process.THE'Saudi Arabia (34 million inhabitants) gets about 50 percent of its drinking water from it, while Israel owns one of the largest plants in Sorek, capable of producing 627 thousand cubic meters of desalinated water per day.

How much does desalinated water cost

A paper by Althesys and Acciona from the title Desalination, a response to the water crisis predicts that, thanks to the improvement of processes and the development of materials, there will be a further decrease in desalinated water prices.Between investment, management and electricity, in 2019 they fell below $3 per cubic meter for the first time.2020 saw a new historical record, with the price reaching $1.50 per cubic meter.“From an energy point of view, desalination can offer strong synergies with renewables – we read in the paper –.The arid areas, where watermakers are most used, are also those with the greatest solar radiation and therefore most suitable for photovoltaic.The union between desalination plants, solar generation, wind and thermoelectric power allows us to limit emissions, reduce energy costs and their volatility linked to fossil fuels”.

Fossil energy and brine are the critical issues

The most well-known problem is the significant amount of fossil fuels that they are often used for power the desalination plants.This is a very energy-intensive process:on average a plant requires an average of 10 to 13 kilowatt hours of energy for every thousand gallons processed (3,700 liters).The economic and environmental costs of a fossil-based process have pushed researchers to look for alternatives, including the development of more efficient separation membranes and desalination units that can be powered by solar energy.

Among the most promising innovations is a desalination technology a autonomous solar energy which does not require batteries.The French company's systems Mascara they are active in several areas suffering from water shortages, including Abu Dhabi and Bora Bora, in French Polynesia.

According to one study published in the journal Science of the total environment, the biggest critical issue however comes at the end of the process, when the brine (waste) is returned to the ocean.In most cases, for every liter of drinking water produced, approximately 1.5 liters of liquid polluted by chlorine and copper are created.This wastewater, if not adequately diluted, can form a dense plume of toxic brine that can damage marine ecosystems, and as the water temperature rises, create dead zone, areas where very few marine animals can live.

However, the last decade has seen a growing academic interest for the recovery of the minerals contained in the brine.Although it is possible to extract them, the high cost of this approach circular so far it has limited its scalability.

The failed project in California

Meanwhile the California is facing its third consecutive year of extreme drought, between rationing and water shortages, was recently failed the project of a 1.37 billion euro desalination plant. Poseidon Water, the company behind the investment, had declared that it could pump up to 100 million gallons of ocean water a day making it drinkable (378 million liters).This did not convince environmentalists and the citizens of Huntington Beach who opposed it, worried about the possible damage to the marine ecosystem and the total cost which, in the end, would fall on taxpayers.

The Italian stalemate and the role of the Salvamare law

These days the Italian government is committed to intervening on the serious drought that is affecting the Peninsula, focusing mainly on savings and efficiency measures for water infrastructure.But desalination does not appear to be one of the options.As underlined by the paper by Althesys and Acciona, in the recent Salvamare law not only is he not promoted, but he even seems to be penalized by an increase in the authorization process.

“Desalination – explains Alessandro Marangoni, Chief executive officer of Althesys – today constitutes a real and quickly implementable response to the water emergency.It is an industrially mature technology, economically competitive and sustainable thanks to research and complementarity with renewable energies.An unfavorable regulatory and socio-political framework is holding it back."The cost of desalinated water is in fact around 2-3 euros per cubic meter, while the price of a cubic meter of water transported by ship is around much higher levels, around 13-14 euros.Many islands, especially in Sicily, Tuscany and Lazio, have already begun to equip themselves with desalination plants.

Almost everyone agrees that desalination can play a leading role in fighting drought.However, if the process is not powered by clean energy and managed in a circular way even in the production of waste, the technology risks not even convincing citizens, as happened in California.