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Is net zero in the water sector just behind the corner in the GCC?

  • Is net zero in the water sector just behind the corner in the GCC?

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SWM Bimonthly frontpage

About the blog

Corrado Sommariva
CEO and founder of Sustainable Water and Power Consultants.
ACCIONA

The journey that took the desalination industry to cut the energy intensity from 25 kW·hr/m3 to less than 3 kW·hr/m3 took about twenty years. However, it was only in the last five years that most of that progress was achieved, as technology shifted from thermal desalination to SWRO and innovations were developed at an unprecedented pace.

The driver that allowed these advances in the sector was good governance, thanks to policies that incentivised efficient use of energy: setting minimum efficiency thresholds for new IWP and providing realistic prices to energy rather than subsidised as was the practise before.

In this way, decreasing energy use became essential for the commercial competitiveness of tender proposals, and the desalination sector discovered that optimising energy consumption was not only good for the environment, but contributed to dropping water tariffs significantly.

Progress continues and the threshold of 2.0 to 2.5 kW·h/m3 is in sight thanks to new solutions and advances in technology.

Decoupling of power and water production across the region has resulted in a growing trend to adopt captive solar photovoltaic (PV) plants, expected to drive water production costs and the energy footprint down even further.

Wastewater reclamation and beneficial use of sludge could turn the wastewater treatment sector from a utility sector to energy generation

The wastewater treatment sector continues in today’s wastewater treatment plant paradox of using energy to “kill” the residual energy in wastewater. The concept is the utility practise of treating wastewater at the lowest possible cost without consideration of the possible by-products.

Today’s installed wastewater treatment has an energy footprint of 0.7 to 1 25 kW·hr/m3 of treated water. However, a large footprint is generated in the process of COD oxidation that, except for various technical ameliorations, remains the same as adopted one hundred years ago.

The sector needs to find incentives to reduce oxidising processes, leaving more carbon in the sludge and generating less CO2. This would allow beneficial uses of carbon-rich sludges (i.e., energy use for waste to energy, anaerobic generation, landscaping and agriculture).  

Along with energy, nutrients and resources in wastewater streams can also be upcycled, recovering nitrogen, organic carbon, phosphorus and other elements precious to the biosphere. The value of struvite as a biological phosphorus-rich fertilizer is gradually gaining commercial momentum versus chemical fertilizers, but the possibilities offered by nutrient recovery are endless and fully in reach of technology today.

Both SWRO and sewage treatment plants could benefit from low or even zero energy costs tariffs if they were designed to maximise their operation when they can be fed by a grid powered with solar energy.

Running a desalination plant when the sun is available and the grid is fed by renewable energy requires storage and larger capacity. On the other hand, water storage provides security against phenomena such as red tides or harmful algal blooms requiring expensive and energy-intensive equipment such as a Dissolved Air Flotation.

The potential for the wastewater sector is even higher, as the reclamation of treated wastewater and the beneficial use of sludge could turn the wastewater treatment sector from a utility sector to energy generation. Wastewater could therefore turn from a nuisance to a resource, and wastewater treatment be conceived as power and nutrient reconversion cycles, for a full “cradle to cradle” process.

Carbon will be further absorbed by forests and greeneries that can be grown using tertiary treated water, which for the most part is currently being discharged to the sea.

Considering the UAE alone produces an average of about one billion cubic metres of treated sewage effluent (TSE) annually, approximately five hundred (500) million trees could be planted, which can further help the industry achieve net-zero carbon emissions much earlier than 2050. 

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