Five years ago I wrote here on the subject Can renewables meet public and political expectations?, concluding with the view that "Australians who expect 100% renewables will be disappointed". The case rested on basic renewables properties, including intrinsic limitations of intermittency, low energy intensity, concerns about the "battery revolution" for large-scale energy storage, and low energy return on investment (EROI).
Armed with five more years of evidence I revisit the topic here.
Cutting carbon dioxide (CO2) emissions is desirable policy. Energy from fossil fuels is a major source of those emissions. The main remedy is "clean energy", defined by zero or low CO2 emissions over a full energy life-cycle covering raw materials, manufacture, construction, etc. Clean energy sources include nuclear and a group dubbed renewables – hydroelectricity, solar, wind, and minor sources such as geothermal and biomass. Widespread environmental concerns about further hydroelectric dam construction will limit future growth of hydroelectricity. Solar and wind have wide public appeal as natural clean sources; they are the acknowledged growth sources. Carbon capture and storage technology, potentially enabling continued use of fossil fuels, is not yet commercial and is excluded here.
Clean energy is electrical energy, it reaches users as electricity, a clean energy economy will be all-electric, and solar and wind are the favoured clean energy growth sources.
Assessing the state of play
The core issues for policymaking are:
1. How much clean electrical energy will Australia need?
2. How will that quantity be generated?
3. How will "everything be electrified", i.e. converted to using electricity?
The second dominates public discourse, with the answer almost always "renewables". Renewables targets are synonymous with clean energy targets. Setting, attaining and raising targets occupy political debate. The ACT has already reached its 100% renewables target. South Australia aims at 75% by 2025, Victoria and Queensland both have 50% targets by 2030. A higher new target, Net Zero Emissions, is being discussed nationally – see below.
Targets are nearly always expressed as percentages. Sometimes their meaning is unclear. Actual numerical quantities are preferred here.
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