Electrification of multi-energy hubs under limited electricity supply: De-/centralized investment and operation for cost-effective greenhouse gas mitigation

Abstract

• Decarbonization via electrification is effective, economic, advisable, challenging. • Limited centralized electricity alters optimal design of new de-/centralized assets. • Multi-objective MILP finds pareto-optimal V2G EVs and mix of converters, storages. • Full year hourly resolution allows for detailed grid and asset operational analysis. • Cost and emission breakdown reveal dominance of embodied emission and upfront cost. Electrification of residential's heating and private mobility is often seen as a cure-all solution to the sector's immense greenhouse gas (GHG) emission problem. However, the necessary supply of affordable, secure, and sustainable centralized electricity is commonly assumed unlimited in related planning efforts. Hence, it remains unclear how beneficial electrification is under limited supply. Therefore, we investigate how jointly planned de-/centralized asset upgrades and Vehicle-2-Home enabled electric vehicles can overcome such limitations exemplarily for five residential building types in Switzerland. Thereto, the proposed, novel optimizations of Multi-energy Systems based on the Energy Hub concept, which extend the classical decentralized Energy Hub perspective to include investments into centralized assets, simultaneously select, design, and operate such assets and vehicles to minimize lifecycle-emissions and -costs while covering thermal, electrical and mobility demands under scenarios of A) unlimited, B) three partially limited, and C) no (stand-alone) centralized electricity. The optimizations prove the centralized supply limitations to be crucial, as achievable CO 2eq mitigations halve on average from A) >60% over B) 45% to only C) 30%. Further, a substantially altered and wide mix of assets is optimal to overcome the identified sole supply bottleneck of electrical energy scarcity during winter. Transitioning from low-cost to low-emission solutions, natural gas based centralized gas turbines and decentralized combined heat and power plants (CHPPs) combined with air-source heat pumps are displaced by biogas CHPPs, ground source heat pumps and centralized photovoltaics, while local photovoltaics and Vehicle-2-Home usage are constants. Surprisingly, all partially limited scenarios including nuclear phase-out and additional cross-border electricity trade stops yield similar results, which enable emission mitigations of 50% over the non-electrified reference without additional annualized cost. Stronger emission mitigation proves prohibitively costly. Overall, considering limited supply avoids overestimation of achievable emission mitigation, underestimation of total costs as well as identification of too simplistic asset portfolios.