Learnings

Outcomes

The following summary details the conclusions from the study:

Conclusions 

•                     Delivery of the Scottish Government’s 2045 hydrogen production target will require raw water supplies of 116 million5 litres per day. This is equivalent to 6% of total current raw water abstraction6 and 13% of total potable water consumption7 in Scotland. It was therefore concluded that although substantial, water consumed by hydrogen projects is likely to account for a relatively small proportion of total annual water demand in Scotland; 

•                     The study found that suitable water resources to supply new hydrogen production infrastructure are likely to exist in all the key regions where that infrastructure is expected to evolve - in fact, in most regions multiple sources could likely support a sustainable water supply for hydrogen production purposes. It was therefore concluded that availability of water per se is not likely to be a constraint on hydrogen production at regional level. More detailed location / source-specific assessment will be required at the project level to assess and evaluate water supply constraints; 

•                     The assessment of available water resources and treatment infrastructure suggested that treated effluent should be the first water source considered for hydrogen production, where it is available in sufficient quantity, due to the absence of competition from other sectors. Utilising effluent for hydrogen production is also likely to have other benefits, including positive environmental impact, reduced permitting requirements, minimum impact on water resources needed for other uses, opportunities for hydrogen project operators to create new revenue streams, and strong social acceptance. Effluent as a source of water for hydrogen production is likely to be available in sufficient quantity across most of Scotland, the exception being Shetland. In the island regions, there is a risk of variability in effluent flow rates during day / night-time (due to the limited populations). However, this can be mitigated by developing sufficient water storage infrastructure. Also, sea water can offer a reliable water resource, due to its abundance and ability to supply high demand. It should be freely available for abstraction with the only constraint being geographical location. In most regions, surface water appears likely to offer a potential water supply resource; however, its overall ranking compared with effluent and sea water options was lower due to risks related to seasonal variability and variation due to climate change (competition for surface water is also high in some regions, where abstraction for hydrogen production may have adverse implications for other uses / ecology). This study suggests that groundwater is only likely to be available in the quantities required for hydrogen production at scale at limited locations such as Fife, Dundee, Glasgow and the Southwest though this should be confirmed on a case by case basis; 

•                     Engagement with Scottish Water suggested that the available headroom in the existing water supply network may not be adequate to supply projected hydrogen production demand in some regions. It was therefore concluded that the use of potable water for hydrogen production at scale should be avoided where possible; 

•                     The assessment of alternative water treatment systems suggested that all five alternative water sources considered could readily be treated to achieve the desired water supply quality for hydrogen production. Water treatment equipment and processes will be generally similar for each of the water sources considered. Water treatment plants are complicated systems; however the technology is matured, and availability of suitable treatment technology should not be a constraint in the development of hydrogen projects. Due to water quality variability, some water sources may require more or less treatment than as described in this report. The site-specific water treatment process, proximity of the water source, water treatment location and hydrogen project location will ultimately drive the CAPEX and OPEX of water treatment systems for hydrogen production; 

•                     Whilst the treatment requirements are likely to be the simplest and lowest cost to implement, the availability of potable water for hydrogen projects at scale is likely to be constrained in most regions with the exception of Glasgow, Southwest and Grangemouth. 

•                     Public perception that sea water is a prohibitively expensive option may not always be accurate, due to the extensive treatment required for any source. In reality, the treatment requirements for sea water are generally similar to those for the other water sources. In practice, the achievable recovery rates of reverse osmosis (RO) systems would likely determine if sea water would require more power for higher pumping rates than the other water sources. Sea water also has the benefit of being able to accept the RO reject without requiring additional treatment. This benefit should not be overlooked when comparing different water sources. Effluent may also share this benefit but needs to be evaluated on the project-to-project basis; 

•                     The electricity costs for water treatment, particularly on large-scale projects, can be significant. Approximately 40% of operating costs for all the different treatment systems considered were found to be associated with electricity supply to the pre-treatment system. Even though the electricity costs are significant in the context of water treatment system, they are likely to be small in comparison to the power consumption by electrolysers. A possible way to ameliorate these costs would be to implement behind-the-meter options, such as direct connection to nearby renewable energy sources - e.g. wind farms. 

•                     For some hydrogen production projects, multiple water sources may be combined to improve the resiliency of the water supply system. In such cases, the associated water treatment systems would need additional flexibility to accept and treat different water qualities 

•                     The costs associated with transporting water over long distances are substantial, and in many cases, developing the necessary infrastructure to transport multiple sources of water may not be practical. It was therefore concluded that wherever possible, new hydrogen production plant should be co-located with the water source. Opportunities to share the cost of developing new water infrastructure with other businesses should also be explored; 

•                     A variety of innovative solutions for securing the water supply necessary for hydrogen production has been identified by this study, namely: 

   ➢use of treated effluent from local industry or Waste Water Treatment Plant (WWTP) 

   ➢ desalination of sea water; 

   ➢ re-purposing water infrastructure from other businesses; and, 

   ➢ utilization of multiple water sources in combination.

These approaches would allow for the water supplies necessary for hydrogen production to be achieved without creating problems of water scarcity for communities living in the vicinity of new hydrogen production infrastructure;

•                     Hydrogen production projects using sea water and effluent as a water resource could also be designed to supply water to other sectors, such as agriculture, during extended dry periods. This would help to enhance water security in the region concerned and considerably improve the social acceptance of new hydrogen projects; 

•                     The study also identified other, wider Circular Economy opportunities associated with hydrogen production projects - including utilisation of waste heat from hydrogen plants for district heating networks, and using electrolytic oxygen in nearby wastewater treatment processes, or industrial furnaces. All these opportunities are likely to have substantial carbon benefits – however, their practicability is clearly heavily location-dependent; 

•                     The availability of water resources to supply new hydrogen production will ultimately depend on location and scale of production. Water infrastructure costs for hydrogen production projects not located in proximity to suitable water supplies are likely to be substantial. Smaller projects are likely to have more flexibility in terms of water sources. Therefore, while other factors are likely to govern the location of hydrogen projects in practice, identification and evaluation of suitable water supply sources should be an important consideration while deciding the location and design parameters of new hydrogen production plant. 

Lessons Learnt

·         Key to the delivery of the project was effective stakeholder engagement with individuals and organisations with interest in the production of hydrogen or the environmental impact on natural resources.

·         Initial data gathering and scenario setting is critical to ensure the outcomes developed are credible. This was emphasised through the close engagement with Scottish Water.

·         The timescales for delivery changed during the execution of the study, primarily due to the extended detail required in several of the Work Packages.

·         The project brought together an international collaboration across different experts to feed into develop the Work Packages and conclusions and recommendations.