According to the State of California progressive climate goals, the energy sector power generation technology mix must evolve by 2045 into a renewable, zero-emissions system. Planning and evaluating options for the technology mix are needed to achieve a cost-effective and timely result. To this end, the State’s electric grid is modeled utilizing a least-cost optimization platform with the goal to identify the profile of technologies that fulfills the projected 2045 demand and while achieving both 100% carbon neutrality and minimal criteria air pollutant (CAP) emissions. Heavy-duty vehicles (HDVs) and refineries are prioritized due to their large contribution to emissions in the two highest emitting economic sectors: transportation and industry, respectively. For each of those subsectors, viable electrification scenarios are established and modeled to identify subsector-specific effects on the least-cost technology mix output. Then, the subsector scenarios are combined to evaluate the cost, air quality, and electric grid implications of the multi-sector electrification in the context of a 100% renewable grid. Using an optimization tool, HiGRID+, two multi-sector scenarios were identified that achieve California 2045 environmental targets. These scenarios implement heavy-duty battery electric vehicle (BEV) and fuel cell electric vehicle (FCEV) deployments along with the substitution of fuel cell systems for refinery processes. Emissions and air quality analyses reveal sufficient emission reductions across the board to meet the State goals. An optimistic versus conservative charging infrastructure analysis revealed that total cost of BEV deployment is driven by charging infrastructure buildout (vehicle to charger ratio) whereas the cost of FCEV deployment is driven by storage capacity assumptions and hydrogen fuel cost. The cost of the two scenarios, one BEV centric and one FCEV centric, are similar.