An Episodic Assessment of Vehicle Emission Regulations on Saving Lives in California.

Historically, California has been a world leader in the development and application of environmental regulations. Policies to address air pollution have reduced criteria pollutant emissions, improved regional air quality, and benefited public health. To this end, California has imposed strict regulations on light-duty, medium-duty, and heavy-duty vehicles to reduce ambient concentrations of health-damaging pollutants such as ozone and fine particulate matter (PM2.5). Here, we compare the impact on air quality in California should California not have adopted on-road vehicle regulations (No Regulations Case) with the air quality associated with current regulations (Regulated Case). Simulations of atmospheric chemistry and transport are conducted to evaluate the impact of emissions on ambient levels of ozone and PM2.5, and a health impact assessment tool is used to quantify and monetize societal impairment. Compared with the "Regulated Case," the "No Regulations Case" results in a maximum peak 8 h ozone level of 162 ppb and 24 h PM2.5 of 42.7 µg/m3 in summer, and 107 µg/m3 and 24 h PM2.5 in winter. The associated increases in the daily incidence of human health outcomes are $66 million per day and $116 million per day during peak pollutant formation periods in summer and winter, respectively. Overall, the findings quantitatively establish the role and importance of on-road vehicle regulations in protecting societal well-being.

Formal optimization techniques select hydrogen to decarbonize California.

System planning across economic sectors is becoming increasingly necessary. Building upon existing solutions for deep decarbonization, the inclusion of renewable capacity to meet up to 8 MMT/year hydrogen demand is carried out. An hourly economic dispatch problem modeling the 2050 California electric grid given this hydrogen demand constraint is solved. Hydrogen demand outside of the power generation sector is fixed, but the demand for power generation is endogenously determined. The factor to consider offshore wind capacity, in addition to a conservative and an aggressive hydrogen technology adoption approach, creates four distinct scenarios to evaluate. The difference in results then provides a basis for discussing the costs and benefits associated with using hydrogen to further decarbonize across all sectors. The carbon reduction achieved outside of the power generation sector is 27 MMT despite a slight increase in carbon within the power generation sector. The seasonal storage requirement for hydrogen spans from 72 to 149 TBtu dependent upon the renewable capacity mix. This level of hydrogen demand results in 21% to 41% of total electric load being dedicated to hydrogen production. Battery energy storage has the lowest energy throughput in the middle of the year coinciding with peak electrolyzer operation.

Net-zero emissions energy systems.

Some energy services and industrial processes-such as long-distance freight transport, air travel, highly reliable electricity, and steel and cement manufacturing-are particularly difficult to provide without adding carbon dioxide (CO2) to the atmosphere. Rapidly growing demand for these services, combined with long lead times for technology development and long lifetimes of energy infrastructure, make decarbonization of these services both essential and urgent. We examine barriers and opportunities associated with these difficult-to-decarbonize services and processes, including possible technological solutions and research and development priorities. A range of existing technologies could meet future demands for these services and processes without net addition of CO2 to the atmosphere, but their use may depend on a combination of cost reductions via research and innovation, as well as coordinated deployment and integration of operations across currently discrete energy industries.