Hydrogen: A thorn in the water sector’s side?

Delivering the UK’s hydrogen strategy could increase water demand by the equivalent of an extra 3.3 million people per annum. Depending on carbon capture and storage, the final total could be far higher.

For water companies already managing rising demand and increasingly scarce supply, this equates to needing to find an extra 5% volume of drinking water annually.

The vast quantities of renewable energy that will need to be sourced for hydrogen production has received ample air time but the critical role that water will play is only now emerging as a key issue to address by industry and policymakers alike.

A joined-up approach has the potential to ensure hydrogen production is aligned with water availability, while co-siting with wastewater facilities could improve the business case for early hydrogen production and help the water sector meet its net-zero emissions targets.

A hydrogen future

While hydrogen plays a minimal role in the UK currently, it is expected to be centre stage in meeting the UK’s net-zero ambitions.

The government has been clear about its desire for the UK to be a major hydrogen producer.

It’s Hydrogen Strategy states that the UK’s geology, infrastructure and technical know-how makes the UK “ideally positioned” to be a global leader in hydrogen.

The strategy set an annual target of 5GW by 2030 in 2021, but this has since been upped to 10GW.

The exact volume that the UK will ultimately require is unknown, but demand is likely to outstrip supply given its potential use within industry, transport, as a form of long duration storage, as a replacement for methane in balancing power plant, and potentially even replacing natural gas in domestic heating systems.

According to National Grid’s Future Energy Scenarios, one of the best indicators of likely demand, the UK could need as much as 330,000tns² of hydrogen by 2030, or as little as 60,000tns².

Work is now underway to try to better understand the extent of likely demand and its location – two key factors which will affect water use.

The production technology used will also have a big impact on the amount of water needed, with the UK looking to make both green and blue hydrogen.

Hydrogen is created by splitting water into its elemental components. What differs between the different methods is how this split is performed.

The preferred option – green hydrogen – uses renewable electricity and between 9-14kg of water per kg of hydrogen produced.

Blue hydrogen is produced from high-temperature steam from a methane source, such as natural gas.

Blue hydrogen requires carbon capture and storage (CCS) to be considered low carbon but uses less water at 6-13kg per kg of hydrogen produced.

As well as drinking water, desalinated water can also be used but this comes at an increased cost and raises environmental questions around brine disposal when carried out away from coastal areas.

Other options being looked at include trying to harness wastewater supplies, such as by Wales and West Utilities in its trial looking at using electrolysis on harvested rainwater.

If successful, wastewater could lower operational barriers and reduce costs for green hydrogen production.

In its hydrogen strategy the government acknowledged the critical role water will play, saying it will require “significant amounts” and will continue engaging with parties in the water industry to ensure “appropriate plans are in place for sustainable water resources.”

However, so far there is little public discussion of water’s relationship with hydrogen production, either with regard to water requirement, or as an opportunity for the water industry.

The water sector’s perspective

Water UK’s Net Zero 2030 Roadmap puts the likely increase in water demand much higher than 5% – it sets it at between 15 and 20%.

This figure takes into account that supply is likely to drop in the future. Many areas in the east and south of England were classified as ‘water stressed’ by the Environment Agency in 2021.

The Climate Change Committee foresees those ‘water stressed’ areas expanding in future unless there are substantial changes in water use.

Michael Taylor, innovation integration manager at Anglian Water Services, says the hydrogen economy must be sustainable.

“[Hydrogen] can bring economic prosperity for a region, but it has to be sustainable and responsible.”

Taylor says that meeting Water UK’s estimate on a national level is “very achievable”, but the difficulty arises at a local scale as it is not easy to transport water from one area to another.

“We may struggle to identify sufficient water resources – especially in areas where there are other water users, like agriculture,” he adds.

Where hydrogen production is located will therefore be key, but as most hydrogen will initially be needed by industry this will be difficult to determine, says Phil Aldous, technical director, Water Environment at AECOM.

Aldous says domestic water changes are largely predictable but “the industrial sector doesn’t have to plan in the same way. Their planning horizons are driven by economics, which makes them much shorter”.

He adds that a balance must be struck between meeting industry’s needs and protecting the environment.

Although the 2030 production target is well within the 2025 to 2050 focus of the Water Resource Management Plans water companies are currently consulting on, the need to provide the hydrogen industry with water gets little more than a passing mention.

Instead, according to Chris Fawcett, director, water management for WSP, that issue is being addressed in five regional plans that look more broadly at water needs. “We need to consider beyond the water industry,” he says.

Power is a key aspect of these plans, says Fawcett, with National Grid’s Future Energy Scenarios providing a basis for potential use.

However, he adds that there is great uncertainty over the exact mix of power production and its likely location due to the competitive nature of the power industry.

Aldous says more feasibility studies are needed and these might need to be multi sector.

“Engage the water companies, engage the regulators, and have that open debate. Not about economics of any particular scheme, but about the principles.

“How do we manage water in a way that there is enough for the environment, enough for public supply, enough for all the other users, particularly agriculture, and enough for the environment so we don’t damage it?”

He says now is a good time for the hydrogen industry to engage, with Water Resource Framework Plans and regional water plans out for consultation.

He warns that unless the industry does engage it might find its production plans come to nothing because its feedstock isn’t there.

Quantifying the potential impacts of larger scale hydrogen production on water resources is one of the main aims of a new project working group at UK Water Industry Research (UKWIR).

It aims to identify what is realistic in terms of hydrogen production compared to government targets.

A larger role for water companies

As well as bringing a myriad of challenges for the water sector, a hydrogen economy could also bring opportunities for water companies to harness the supply chain to lower emissions from their water processing activities.

As well as looking at water demand, the UKWIP group will also consider how the water industry will both use and potentially produce hydrogen.

It aims to provide guidance on business models for water company engagement in the hydrogen value chain, of which there are several options.

One is to utilise the by-product of hydrogen production – oxygen.

Taylor explains: “There is little demand for oxygen from electrolysis, but the water sector may be positioned to use it.

“Co-locating hydrogen electrolysis with wastewater treatment means you could use the oxygen in the process. It enhances the treatment and nutrient removal, so it could have a positive impact.”

Roughly 55% of the energy consumed by a typical sewage works is used to process wastewater, according to Thames Water statistics, with reducing carbon emissions from treatment works also a key focus for the industry.

Taylor adds that sites could be chosen for early hydrogen production based on the location of water treatment works rather than solely on existing energy sector assets.

Such a concept could help cut costs in Australia, where the drought-prone climate and reliance on fossil fuels makes hydrogen production prohibitively expensive.

A thought leadership paper by Jacobs, published in 2020, considered the potential role of wastewater treatment plants in accelerating the development of Australia’s hydrogen industry.

Co-siting hydrogen production with wastewater treatment works would cut capital and operating costs for the water supplier.

At the same time the sale of oxygen would allow hydrogen production to be commercially viable while remaining in the necessary competitive price range.

Another route water companies are exploring is to become hydrogen producers themselves.

Again, there are several technologies in trial at various stages of the water supply cycle which could produce hydrogen for use by the companies themselves and potentially others.

Although it requires more processing, water companies are also exploring if wastewater can be used instead of drinking water.

In 2020 NI Water became the first company in the UK to produce hydrogen through electrolysis at a wastewater treatment site when it installed a 1MW electrolyser to prove it could increase processing capacity, reduce carbon emissions and offer grid flexibility.

Another option is to use microbial electrolysis cells, such as those trialled by Severn Trent at its sewage processing plant at Minworth to treat wastewater while also producing hydrogen.

These cells consist of electromagnetic organisms which grow on recycled carbon fibre mats and break down organic pollutants in wastewater to produce hydrogen.

Severn Trent is also working on another trial which aims to convert ammonia from sewage into hydrogen, rather than just destroy the ammonia, as is current practice.

If successful, the study will develop a more efficient method of processing the waste product while also producing a clean fuel which could be used in the transport industry.

Severn Trent alone has the potential to recover up to 10,000 tonnes of green ammonia per year from its wastewater treatment plants, which could be converted into 450 tonnes of hydrogen.

An extensive study into the commercial viability of water companies producing hydrogen has been carried out by Welsh Water.

It plans to convert sewage derived biogas to renewable bio-hydrogen at a plant near Cardiff.

The plant would utilise 35GWh of biogas to help generate 2000 kg per day of hydrogen, enough to fill up the equivalent of 100 buses.

Welsh Water says that using the biogas to produce renewable fuels could have up to 10 times larger decarbonisation impact than using it to produce renewable electricity.

However, a key step in the process was establishing that there would be sufficient local demand for the hydrogen to ensure commercial viability.

Working with Cardiff Council, its study concluded that there was significant appetite within the region from buses, refuse collection vehicles and critical response vehicles – particularly blue light vehicles for the police.

In fact, the potential hydrogen fuel cell vehicle user demand in South East Wales could meet all daily production from the proposed facility within two years of operations, commencing in the mid-2020s.

The UK water industry estimates that approximately 2 TWh of biogas could be diverted to produce biomethane. If half of this biogas is used to produce low carbon hydrogen, the industry has the potential to produce 20 million kg of hydrogen.