Abstract
Electrification of all sectors needs net zero electricity (NZE) to slash greenhouse gas emissions (GHG), 38% of the global annual energy-related GHG of 34 Gt CO2eq. NZE is to avoid climate catastrophe, predicted at 2.7 °C rise in global mean temperature by 2100 (at 50% probability). There is no consensus approach to the sustainable development of NZE systems. This study has developed a novel, rigorous, holistic life cycle assessment methodology for a sustainable NZE roadmap or pathway. It identifies the leading fifteen countries with the highest gross domestic products with over 90% GHG. It compiles Ecoinvent life cycle inventory for in-country NZE systems and calculates their life cycle impacts using ReCiPe, Impact 2002+, and Environmental Prices methods. The global mean ranking of non-fossil systems is (kg CO2eq/GJ, US$/GJ): hydro-run-of-river (1.49, 0.73), hydro-reservoir (7.77, 0.91), wind:1–3 MW (7.37, 3.9), solar-20MW (13.94, 4.18), solar-50MW (15.29, 4.84), wind:>3 MW (9.55, 9.68), geothermal (19.99, 9.84), and bioenergy (12.09, 36.28). In decreasing order of significance, sustainability determinants are particulate emissions, land use, human toxicity, climate change, acidification, and ionisation radiation. To hit NZE (0.02–0.24 kg CO2eq/kWh), Brazil, the USA, Spain, Germany, France, Canada, Japan, Italy, and the UK need 52–95% decarbonization. Russia, Indonesia, Mexico, and Turkey can achieve 61%, 31%, 6%, and 4% decarbonization to 0.24–0.56 kg CO2eq/kWh, while with 0.52 and 0.65 kg CO2eq/kWh, China's and India's transitioning may slow down by this time. Robust NZE relies on improving health in developing countries, de-fossilized resource-technology diversification, and natural soil organic carbon sequestration, enhancing biodiversity and forestation.