Solar and wind offer safest route to decarbonized electricity mix

Global electricity generation, which accounts for around 40% of the world’s C0₂ emissions, is the human activity which offers the most extensive low-cost method of combating global warming and addressing pollution.

That is one of the, perhaps unsurprising, chief findings of the Environmental co-benefits and adverse side-effects of alternative power sector decarbonization strategies study published in Nature Communications. The authors of the report – published by the Potsdam Institute for Climate Impact Research, in Germany – claim solar and wind are more effective than any other energy source at mitigating global warming whilst causing the fewest negative human health impacts.

The researchers said electricity generation is not only the cause of huge amounts of emissions but can also be responsible for air and water pollution, land occupation, water use, ionizing radiation and nuclear waste and fossil and mineral resource depletion.

Side-effects

The study set out to consider adverse side-effects, as well as benefits, of a decarbonized global electric system and was based on two assessment methodologies. ‘Integrated assessment models’ are typically used to to analyze different climate change mitigation strategies and their implications and ‘life-cycle assessment’ is useful to predict environmental impacts, with the report’s authors saying the latter was necessary as integrated assessment models do not sufficiently account for performance changes in clean energy technologies, especially with regard to PV.

The study presents four scenarios. ‘NewRE’ considers an energy mix dominated by renewables, ‘conventional technology’ posits a future with only 10% solar and wind penetration, ‘full technology’ proposes continued fossil fuel use mitigated by carbon capture and storage and a baseline scenario has no restraints on greenhouse gas emissions.

Mineral resource use

The NewRE scenario envisages the most extensive mineral resource depletion due to the higher per-unit metal requirements of renewable technologies, particularly solar. Solar and wind are also said to require more substantial upfront investment as well as the additional metal resources required for new grid infrastructure. Unlike fossil fuels, however, the mineral resources exploited are suitable for recycling, the report notes.

“The low-carbon transformation, especially if it relies heavily on wind and solar technologies, can be expected to have profound implications for the geopolitical landscape, pointing to the need for flanking the global clean energy effort with an integrated critical-materials strategy,” the authors of the study said.

Land use, toxicity

The researchers said although climate policy tends to increase power-system related pressure on land use, that is largely down to the requirements of growing biomass energy crops, highlighted as the greatest driver of ecosystem damage. “On a per-megawatt-hour basis, electricity from biomass with CCS (carbon capture and storage) is more than 20 times more land-intensive than hydropower, coal with CCS, or CSP [concentrating solar power], and exceeds wind and PV by around two orders of magnitude,” wrote the authors.

The study notes the additional land required for grid upgrades related to increasing solar and wind energy generation would be small compared to the footprint of the existing grid network.

Renewables release fewer chemical substances than other power sources, according to the study, with fossil fuel extraction and agrochemical-driven bioenergy the worst offenders in that regard, on a per-megawatt-hour of electricity generated basis. “As a consequence, ecotoxicity impacts in the NewRE decarbonization scenarios are around 30% lower than those in FullTech,” added the authors in the report.

Water

Solar and wind also reduce the demand for water compared to nuclear, which uses it to cool reactors, as well as requiring less water use than hydropower and bioenergy.

“Wind and solar-based decarbonization ([the] NewRE scenario) consistently achieves [the] highest reductions in health-related environmental impacts,” the paper states. “The world is currently witnessing a dynamic and robust growth of wind and solar power which is also expected to become the most important contributor towards near-term CO₂ reduction efforts worldwide.”

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