So You Want to Make H2 at Your WRRF? Synergies, Pitfalls and Opportunities

Learning Objective Determine if hydrogen (H2) production makes sense for a water resource recovery utility, with a particular focus on the United States market, while incorporating a global perspective. The hydrogen economy is in its infancy, and therefore the optimal methods to gain value from hydrogen are complex and influx. This presentation will identify and clarify: (1) An approach to determining if a utility should even consider H2 production, (2) Benefits that may be obtained, included the state of the current market, and economic incentives, (3) Synergies & challenges of H2 production and WRRFs The audience should gain a streamlined understanding of the hydrogen economy, and if and how a WRRF might fit into that economy. Why Generate Hydrogen? The immediate, tactical driver to generate H2 is economic. Much like renewable natural gas generated from biogas at WRRFs, H2 is a product that: 1.Can be used to supply municipally owned: a.vehicle fleets, b.power plants, or 2.can be sold in the market. If the utility plans to sell the H2, it is critical to understand the surrounding market, most importantly potential off-takers and potential infrastructure to receive and convey the H2. While the tangible benefit of H2 production to a utility is chiefly economic, it can have great public perception benefits, noting H2's role in global decarbonization. In addition, it has the potential to accelerate the implementation of onsite renewable energy production by serving as an energy storage medium when power demand is less than renewable supply. What Type (Color) Hydrogen to Produce at a WRRF Depending on the H2 generation method and feedstock, H2 can be classified by color as shown in Figure 1. Due to regulations or economic incentives, low to zero greenhouse gas (GHG) H2 use is growing as a replacement for high or medium GHG H2, and as a replacement for carbon-based fuels. There are currently no regulations or incentives to use lower GHG H2. H2 sale price in the US is currently the same, regardless of its origin. However, governments are beginning to incentive production of lower GHG H2. These incentives, while not yet final, are heavily based upon on lifecycle GHG emissions that result from the clean H2 production process. Due to the downward production cost trajectory of lower GHG H2, and the significant capital expense required for new hydrogen production facilities, WRRFs should focus on producing low GHG H2 to meet the optimal future production market. How to Integrate Hydrogen Production into a WRRF The reason to integrate H2 production with a WRRF is to reduce the overall costs compared to separate H2 production and wastewater treatment, thereby creating a higher economic value for the producer. Establishment of project ownership, costs and benefit allocation should precede any analysis of H2 production at a WRRF. The major input to hydrogen production is energy, and it is helpful to look at the synergies at a WRRF as a transformation of energy to a different form (with inefficiencies along the way): (1) Renewables/nuclear/grid to H2 via electrolysis, (2) by mass, produces an 8:1 ratio of (oxygen) O2:H2. (3) Biogas/methane to H2 via Pyrolysis, (4) by mass, produces an 6:1 ratio of (carbon) C:H2. Each WRRF is unique and specific synergies must be analyzed in the context of that WRRF. To illustrate the synergistic opportunities, an evaluation of H2 production at the Encina Water Pollution Control Facility in Carlsbad, CA was developed. This evaluation is in the context of a long-term energy resiliency assessment, and full results will be provided in the presentation. Figure 2 presents this WRRF with all planned upgrades included, and areas of the WRRF highlighted in green that have synergies with hydrogen production. Table 1 presents the synergies, including primary benefits. The presentation will provide a more detailed discussion of the synergies. Questions The feasibility of H2 production at a WRRF must consider other uses of WRRF resources (the presentation will discuss the below questions): Is H2 production from the highest and best use of WRRF effluent? Is H2 production the highest and best use of WRRF biogas/power? Is H2 production the highest and best use of WRRF footprint? Can WRRFs compete with large scale hydrogen production companies? Conclusions and Summary There is tremendous interest in the integration of H2 production with WRRFs to capitalize on their synergies. When considering implementing H2 production at a WRRF, utility owners must consider:

*The overall project/governance structure; who is owner, what is the market, and how to allocate the costs and benefits.

*The current and planned WRRF site and treatment process; what the specific synergies would be, and the true value of those synergies when compared with other ways to create value from the WRRF. As the hydrogen economy is in its infancy, there are currently simpler, more feasible methods to capitalize on the water and power recovered at a WRRF. However, visionary WRRFs can find realistic synergies with hydrogen production that could facilitate its implementation, especially as they look to recover and utilize excess energy, as restrictions on carbon emissions increase, and the hydrogen economy matures.