3.4 Technical maturity

All technologies considered in the decarbonization scenarios modeling are either currently in development or have been deployed, though some are at more nascent stages. To appropriately compare the scenarios, it is important to consider which scenarios rely more heavily on technologies that are less developed, and therefore have greater uncertainty around their long-term viability and/or their long-term costs.

The implications of varying degrees of technical maturity are three-fold. First, the costs and performance of these technologies should be monitored to continuously refi ne the assumptions that inform decarbonization pathways. Second, given uncertainty of evolving technologies, it is important to pursue pathways that provide more technology options to enable long-term optionality to de-risk the route to decarbonization. Third, investments in nascent technologies could help accelerate market transformation. The High Clean Fuels scenario relies upon hydrogen blending in pipelines, which shows promise across many demonstrations in other jurisdictions on similar pipeline materials.

The High Clean Fuels scenario presumes that 20% blending by volume can be achieved in the existing California infrastructure with relatively low additional investment required to accommodate and that hydrogen can be extracted from blended pipelines with suffi cient purity to serve dedicated end-uses (e.g., refueling stations). This level of hydrogen blending in natural gas pipelines has not been tested directly in California’s infrastructure. Research suggests that up to 20% blending of hydrogen generally can be blended into the gas distribution system without signifi cant risk72, though the cost required to safely blend hydrogen through the California gas system is still uncertain. The High Clean Fuels scenario also relies upon a large scale-up and cost-down of renewably powered electrolysis.

Recent scaleup and funding commitments, including the European Union initiative to deploy 40 gigawatts of electrolyzer capacity by 2030, bode well for prospective scaleup.73 While all modeled scenarios rely on electrolysis to some extent, the High Clean Fuels scenario involves the greatest ramp up of electrolysis.

Even more challenging, the No Fuels Network scenario assumes no gas-fi red and thermal generation, and therefore, in the decarbonization modeling, relies on long-duration battery storage to meet system needs after multi-day events with low renewable generation. While battery storage technologies to meet these long-duration requirements are in development, they are in early stages and have yet to be demonstrated at even pilot scale.74 Because the No Fuels Network” scenario relies on unknown or yet proven resources to provide electric system reliability, it is rated and presented as the most challenging case when it comes to technical maturity.

Finally, the Resilient Electrifi cation and the High Carbon Sequestration scenarios have a more favorable rating on technical maturity, as the uncertainty around their feasibility is smaller. Increased electrifi cation in urban areas and installation of fuel cells at large scale, although technically challenging, are better known and understood technologies, notwithstanding uncertainties for scaling electrifi cation to 100% of buildings by 2035. Carbon capture and sequestration are less uncertain technologies having been in use for industrial purposes, although they still have inherent technological risk and ultimate cost is uncertain in a California-specifi c context.

72United Kingdom Health and Safety Executive, “RR1047 Injecting hydrogen into the gas network - a literature search,” p. v, 2015, available at: https://www.hse.gov.uk/research/rrpdf/rr1047.pdf; see also Gas Technology Institute, “Review Studies of Hydrogen Use in Natural Gas Distribution Systems,” p. 1, December 2010, available at: https://www.nrel.gov/docs/fy13osti/51995.pdf (Appendix A to Melainaet al., “Blending Hydrogen into Natural Gas Pipeline Networks: A Review of Key Issues,” March 2013) 73Electrolyzer cost curves in “High clean fuels” scenario are in line with the European Commission’s Advanced System Studies for Energy Transition (“ASSET”) Project; see Capros et al., “Technology pathways in decarbonisation scenario,” July 2018, available at: https://ec.europa.eu/ energy/sites/ener/fi les/documents/2018_06_27_technology_pathways_-_fi nalreportmain2.pdf. 74Tuttman, M. and Litzelman, S., “Why Long-Duration Energy Storage Matters,” ARPA-E, April 01, 2020, available at: https://arpa-e.energy.gov/ news-and-media/blog-posts/why-long-duration-energy-storage-matters.