Andrew Hodgkinson | Manager Process and Treatment Technology, Houston | 08 February 2022
No water, no hydrogen. It's that simple. Or is it?
The momentum behind low-carbon hydrogen is growing. Industry leaders across the world are developing ambitious and potentially game-changing projects to produce low-carbon fuels such as hydrogen. Meanwhile, others are considering how hydrogen might fit into their business going forward. While the push to increase production rises we can’t forget how important water is to realizing hydrogen’s full potential.
Antoine Lavoisier first isolated hydrogen in 1783. Burning hydrogen generates water, hence the name ‘hydro‑gen.’ The opposite is also true, hydrogen is made from water.
Now, almost 240 years later, we’re helping our clients make hydrogen a truly ‘green’ fuel through careful design of the entire product value chain, including water supply and treatment.
Green hydrogen production uses renewable energy, and it is a booming industry. Worley is currently helping to deliver several electrolyzers in the 100–200 megawatt (MW) range. Although these electrolyzers seem large today, soon they will be dwarfed by multi-gigawatt (GW) scale plants producing thousands of tons per day of this versatile and low-carbon fuel.
While water supply and treatment remains a key challenge in existing energy systems, many modes of new energy have critical water challenges to solve as well. This is especially true for hydrogen, which uses water as a feedstock and requires treatment to a specific level of purity before it can be hydrolyzed.
Worley has already delivered, or is currently working on, over 120 hydrogen projects or studies, the largest of which is a 36 GW electrolytic hydrogen production system. Once built, this facility will be large enough to support world-changing industries, such as green steel production. Green steel will mean that, for the first time, carbon will play no part in the smelting process.
Pure water is critical for hydrogen fuel production. Roughly 5 metric tons of pure water a day is required for every megawatt of electrolyzer capacity. Accessing that amount of water isn’t as simple as turning on the tap, but we specialize in making it seem that simple.
Solving your water challenges upfront can help to ensure smooth sailing throughout your hydrogen project journey.
Don’t assume that fresh or potable water is always available. The cost and complexity of producing demineralized water is highly dependent on source water quality whether it comes from groundwater, seawater, reused wastewater, or elsewhere. Careful option analysis ensures you select the right source for your unique project needs.
Water infrastructure can be 10 percent of the total installed cost for hydrogen projects. Combined with limited water availability this is enough to affect project viability.
Water sourcing can add years onto a project schedule if water rights or permitting are an issue. Early identification of water sources allows for time to find an alternative.
An electrolyzer of 100 MW capacity consumes roughly 500 tons of water per day (tpd) and produces roughly 50 tpd of hydrogen. If the system is water-cooled, the water required will be doubled. Thus a large hydrogen project, say 30,000 MW, will require at least 150,000 tpd of pure water. This is approximately the water demand of a city with a population between 500,000 to one million people.
It’s unlikely that new water consumption of this scale will be accepted at many inland locations. But many inland locations (i.e. the southwestern United States, central and western Australia, North Africa, or the high plains of South America) are ideal for solar energy production. Since solar energy will often be paired with hydrogen production, water supply is a key issue to address.
The sheer magnitude of water required for hydrogen production will be most readily available from the ocean. Seawater desalination plants can provide pure water for electrolysis at whatever scale is required. And because of that, we frequently incorporate this option into our clients’ plans.
In cases where the renewable energy source is not co-located with the electrolyzer, trade-off studies will be needed to determine the optimum location for the electrolyzer. Which has a better cost-benefit? An electrolyzer located inland, with water transported from the ocean? Or locating the electrolyzer near the ocean, while accounting for the renewable energy lost during transmission from the energy source.
When seawater desalination is not available, large-scale hydrogen production will be recognized as a major new consumptive water use. One that may need to be weighed against other uses. Consequently, many regions, even those not traditionally considered water-stressed such as Northern Europe, may turn to large-scale wastewater reuse to meet this new water demand.
We know this to be true since we recently assisted a large city in Northern Europe develop plans to create a major new industrial water supply using wastewater as the raw water source. This concept is used increasingly in major cities around the globe. In Queensland AU, Worley was part of a 2.5 billion dollar wastewater reuse and transport project capable of supporting both industrial users and the water supply for metropolitan Brisbane’s 2 million people.
As evaporatively cooled coal power plants become obsolete, the large amount of water they consume can be reallocated. Freeing up that water supply will permit new electrolytic hydrogen production in renewable energy-rich areas, which are currently considered water constrained. For instance, a water-cooled 2000 MW coal-fired power plant consumes around 100,000 tons of water per day. If the coal power plant is closed and its water offtake rights become available for hydrogen production, there will be enough water to support at least 18,000 MW of electrolysis.
Much of the water consumed in electrolysis can be recovered if hydrogen is used in processes that permit steam recovery. Such processes may include hydrogen-fueled ore smelters and fuel cells.
Fuel cells offer the potential to simultaneously produce power, heat, and water. In severely water-constrained locations (such as the high plains of Chile), by-product water from industrial use of hydrogen for power generation and metal smelting, will prove especially useful.
Hydrogen production also yields large quantities of a potentially valuable by-product, oxygen. For each megawatt of electrolyzer power, approximately 3.9 tons per day of oxygen is released. This poses an enormous opportunity for the development of innovative oxygen-dependent applications including chemicals processing, waste treatment, and aquaculture.
A lack of process reagents may potentially affect hydrogen projects relying on offshore and onshore wind energy fields. Remote solar power fields coupled with hydrogen projects may experience similar logistical constraints.
However, this problem can be overcome by producing reagents locally. When there is a large supply of sea water, electricity, hydrogen, and oxygen it is possible to produce most typical water treatment reagents on site such as:
Hydrogen requires liquefaction for storage and transport. Some of the logistics associated with this can be overcome through a complementary technology, ammonia production.
Much of the world’s food supply depends upon fertilizer made from synthetic ammonia, manufactured using fossil fuel. However, ammonia is an efficient transport vector for hydrogen, because hydrogen is much harder to liquefy and transport than ammonia, and ammonia has a very high hydrogen density.
Ammonia can be used as a fuel for combustion systems without requiring a hydrogen extraction process. Ammonia plant wastewater must also be managed.
Water availability is a deciding factor for any hydrogen project but there are many other details to consider. And it’s best to consider these trade-offs early, during source and treatment selection.
Facility design factors add to the challenge. These might include source water, pretreatment, heat integration, redundancy, peak demand flows, and storage.
You also need to make environmental design considerations and consider local weather at your site. Seasonal changes to water temperature will impact your treatment approach. Water salinity and water quality changes whether seasonal, weather related, or tidal can all have an impact on water treatment as well.
Early water management planning will ensure smooth sailing throughout your hydrogen project journey. We provide total water management solutions, from source selection, permitting, and treatment, to operations and maintenance, through to waste management. If you are facing water challenges on your hydrogen project we’re here to help. Reach out to our global water team at WET@advisian.com.
Understanding water-related risks and opportunities allows you to implement better project approaches. Stay tuned as we take a deeper dive into water usage considerations across the energy transition.
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