Solar desalination dome promises record-low water price

A new solar dome technology claiming to produce desalinated water cheaper than traditional methods is hoping to put Saudi Arabia’s new NEOM vision on the global water map.

Called “solar dome”, the decentralised solution uses concentrating solar power (CSP) technology to treat seawater.

With a predicted price of $0.34/m3, the team behind it claim the solution will be considered “significantly lower” than desalination plants using reverse osmosis (RO) membrane methods.

Developed at Cranfield University, UK company Solar Water will work with NEOM to develop the first project on a 26,500 km2 area in north-western Saudi Arabia.

The first project is expected to be completed by the end of 2020.

How the “solar dome” works
Claimed to be 100% carbon neutral, the process involves piping seawater under a “glass-enclosed aqueduct system”, which heats the water as it travels into the dome.

These structures, made from glass and steel, will vary in size from 20m to 120m, according to the company.

An array of parabolic mirrors, or “heliostats” that surround the sphere, concentrate the solar radiation onto the dome.

This transfers the heat to boil the seawater, creating a “cauldron effect” where the water is superheated. After evaporation, steam condensate is then piped as freshwater to reservoirs and irrigation channels.

Secondary treatment will then be necessary to create drinking water.

Interestingly, NEOM claims the process can also operate at night as solar energy generated throughout the day can be stored, suggesting energy storage or battery capabilities.

Another big claim is that this arrangement will “reduce the total amount of brine that is created”, as “no brine is discharged into the sea”.

With the by-product from desalination labelled as “one of the world’s greatest environmental challenges”, it raises the question of what happens to the concentrated brine?

Solar Water said it would gather at the bottom of the dome’s basin to be extracted and sold commercially.

This includes commercial by-products for industrial use, including lithium batteries, grit for roads, fertiliser or detergents.

Industry reaction on social media
Speaking to Aquatech Global, desalination industry veteran Leon Awerbuch said it’s currently difficult to assess the reality of the dome as very little technical information has been made available.

Speaking to Aquatech Global Events, he said: “The price of 0.34 $/m3 with high recovery is extremely ambitious, but there isn’t any information on energy recovery. Inside the dome, there could be scale deposition if they use high-temperature steam to focus on seawater. So, there are challenges, I hope NEOM has experienced advisors.”

Awerbuch posted the dome announcement on LinkedIn, sparking mixed comments about whether the promised low price included capital costs (CAPEX), or was just the operating cost (OPEX).

One person questioned where the brine by-products would go: “Interested to see the ‘no brine’ disposal, where do the undesirable ingredients finally go?”

Two others praised the low price, saying “the production cost of USD 0.34 per cubic metre of desalinated water is amazingly low” and “It is very fascinating. 0.34 $/m³ is really competitive!”

Meanwhile, others remained sceptical, stating “This seems too good to be reasonable for me. How to recycle the waste heat is the key” and also: “The article doesn’t indicate whether the USD0.34/m3 is only Opex or if it also pays the Capex. If [this price] is the total cost, I agree with most that it is a low number. However, if Capex is not covered, and is not mentioned, there are other initiatives out there that are competitive.”

Where and what is ‘NEOM’?
Meaning “new future”, NEOM is being built as a cross-border city in the Tabuk Province of north-western Saudi Arabia as a “living laboratory”.

Designed as a “place where entrepreneurship and innovation will chart the course for this New Future”, NEOM will be a centrepiece of Saudi Arabia’s 2030 Vision plan to shift its historic dependence away from oil.

Towns, cities, ports and enterprise zones, research centres, sports and entertainment venues will all be built as part of the ambitious project near the Red Sea.

The vision of His Royal Highness Crown Prince Mohammed Bin Salman, NEOM will eventually be home to one million citizens.

Saudi Arabia’s National Water Strategy 2030
Water demand in Saudi Arabia has been growing at a rate of 7% annually, with agriculture accounting for 84%.

The country has been heavily reliant on subsidised desalinated water, providing 60% of urban water supplies.

H.E. Abdulrahman Al-Fadli, Saudi Arabia’s Minister of Environment, Water and Agriculture, said the solar dome “supports Saudi Arabia’s sustainability goals, as outlined in the country’s National Water Strategy 2030, and is fully aligned with the sustainable development goals set out by the United Nations”.

The Saudi National Water Strategy 2030 has the ambition to reform the water and wastewater sectors, ensuring sustainable development of water resources while providing high-quality services.