How Can the Water Sector Engage with a Future Hydrogen Economy?

By Andrew McLeod, Process Engineer, Bioresources, Water, Energy and Environment, and Stephen Horrax, Director of Carbon and Energy Consulting.

The transition from a carbon-based economy to a hydrogen economy has been promoted as a route to address the climate emergency for a long time. Today, the critical decarbonizing role of hydrogen is being brought into ever sharper focus, through national net zero strategies and huge planned governmental and industrial investment around the globe.

In the immediate wake of the United Nations climate change conference COP26, the U.S. passed the $1.2 trillion Infrastructure Investment and Jobs Act, with billions dedicated to hydrogen. In August 2021 the U.K. released its hydrogen strategy, including a target to produce 5 gigawatts (GW) by 2030 and for 20-35% of U.K. energy to be hydrogen-based by 2050. Earlier in July 2020, the European Union released its Hydrogen Strategy for a Climate Neutral Europe, highlighting investment to build up to 40GW of hydrogen by 2030 and up to €42 billion for electrolysis.

However, from the perspective of delivering fast and efficient decarbonization, there remains significant uncertainty around scale, the resources used (e.g. renewables or fossil gas with carbon capture and storage), and timelines for the production of hydrogen and its distribution and end-use.

How can Water and Sewerage Companies (WASCs) produce hydrogen?

Perhaps the clearest link between WASCs and hydrogen production is through the electrolysis of water using renewable electricity. In Australia, Jacobs has highlighted the neat synergy of this production pathway at treatment works, which consumes final effluent as a non-potable source of water to create hydrogen and a pure oxygen co-product, which can be recycled to enhance aerobic wastewater treatment on site.

There are numerous other potential pathways under investigation by which WASCs could create hydrogen:

• Pathway 1: Final Effluent (FE) - using FE as a non-potable source of water for electrolysis.
• Pathway 2: Ammonia (NH₃) - stripping NH₃ from sludge liquors and converting it into hydrogen, e.g., by electrolysis or thermal cracking technologies.
• Pathway 3: Advanced Thermal Treatment (ATT) - separation of pure hydrogen from the syngas generated by gasification or pyrolysis of raw sludge or treated biosolids.
• Pathway 4: Steam Biogas Reformation (SBR) - separation of pure hydrogen from the syngas generated by direct conversion of methane in raw biogas (from anaerobic digestion of sludge).
• Pathway 5: Steam Methane Reformation (SMR) - separation of pure hydrogen from the syngas generated by conversion of methane in biomethane upgraded from biogas (from anaerobic digestion of sludge).

The production potential of pathways 2-5 is significant but limited by the production of sewage sludge and in some cases by which sludge treatments are favored (e.g., if composting or raw sludge incineration is predominant). However, the FE pathway is independent of sludge and only technically constrained by the availability of FE and renewable electricity.

Why should the water sector get involved with hydrogen?

In parallel to international agreements and national strategies on decarbonization, WASCs will also be looking at effective ways to reduce their significant carbon emissions associated with treatment and related activities. For example, in November 2020 Water UK published its Net Zero 2030 Route map, promptly followed by route maps of individual U.K. WASCs. Many of these route maps cite hydrogen as a possible practical decarbonizing solution, e.g. for transport emissions.

Recovering hydrogen from wastewater and sludge could further the transition towards a more circular economy and introduce new opportunities to gain revenue from resources traditionally considered to be wastes. For example, in the U.K. the Renewable Transport Fuel Obligation (RTFO) provides financial support to the provision of renewable fuels, including hydrogen. Incentives for other applications, such as gas grid injection remain out to consultation. These align well with existing U.K. experience base around the production and use of biomethane.

Finally, several of the hydrogen production pathways can enhance wastewater and sludge treatment and reduce process carbon emissions in addition to the carbon benefit of the hydrogen itself. For example, the FE pathway can improve the efficiency of aerobic treatment through the provision of pure oxygen as a replacement for air, which comprises only 21% oxygen. A recently funded innovation project led by Anglian Water and partnered by Jacobs will integrate the FE pathway with new treatment technology at the demonstrator scale to make the most efficient use of the oxygen and achieve a step-change reduction in nitrous oxide process emissions.

What can WASCs do with the hydrogen they make?

WASCs are likely to have internal demand for hydrogen, for example as a zero-emission replacement for diesel fuel in the heavy-duty transport of sewage sludge by road. However, hydrogen fuel cell and internal combustion heavy-duty trucks are only now becoming commercially available and currently lack supporting refueling and maintenance infrastructure. This means hydrogen is still not the straightforward choice for WASCs to decarbonize their heavy-duty transport. Other options can also be considered, such as battery electric trucks (more efficient but currently less practical) and biomethane trucks (readily available but not with zero emissions).

Hydrogen could also be exported to gain revenue, e.g., as a vehicle fuel or to decarbonize industrial processes or national gas grids. However, hydrogen is notoriously difficult to transport as it is not easily compressed or liquified. This suggests the geographies of specific wastewater treatment works and sludge treatment centers will be crucial to the export potential of hydrogen created by WASCs, at least until national hydrogen infrastructure (such as dedicated hydrogen pipelines) is developed, or additional process steps to create a suitable hydrogen carrier (such as ammonia) can be accommodated.

Risks and rewards will vary globally based on the national regulation of water industries and what governmental financial incentives are in place or planned to support hydrogen production.

How Jacobs is supporting the water sector and the transition to a hydrogen economy

It is increasingly clear that the drive toward hydrogen for decarbonization is real and that links into the water sector are becoming more tangible. However, the picture remains highly complex and overarching company and sector-level hydrogen strategies still need to be developed.

Jacobs’ thought leadership in this area aims to unpick some of the complexity, to manage some of the uncertainty around hydrogen and even provide a nucleus around which firm hydrogen strategies can be devised. This thought piece will comprise a series of six discrete parts, providing a global overview, examining the individual hydrogen production pathways in finer detail and exploring the engagement of the water sector with an emerging hydrogen economy, using the U.K. as a case study. This series was originally published on LinkedIn and is available to read at the links below.

The Water Sector and Hydrogen

Part 1: A Global Overview of the Series

Part 2: Final Effluent (FE) Pathway

Part 3: The Ammonia Pathway

Part 4: The Advanced Thermal Treatment (ATT) Pathway

Part 5: Biogas Pathways

Part 6: Managing, using and exporting hydrogen