Renewable energy is not just good news in terms of reducing greenhouse gas (GHG) emissions, but has much wider beneficial effects which impact directly on human and environmental wellbeing, according to a recent report by the European Environmental Agency (EEA). Renewable energy sources such as wind and solar power use no fuel. No fuel means no combustion and therefore no release of other materials contained within fuels into the atmosphere. This brings important benefits across the environmental spectrum.
Take the simplest molecule, H2. Combustion produces water (H2O) as a by-product as the H2 reacts with O2 in the air. As there is no sulphur present, burning hydrogen does not produce sulphur oxides (SOx), but hydrogen’s high flame speed does produce some thermal nitrogen oxides (NOx). Move up a step to natural gas, CH4. Still a pretty simple molecule. Breaking the hydrocarbon bond produces steam and carbon dioxide and some thermal NOx as the flame reacts with nitrogen in the air. Take another step up in molecular complexity – oils and coals for example – and the carbon emissions rise, owing to the higher carbon content, as do the NOx emissions. These hydrocarbons contain nitrogen so they produce both fuel NOx and thermal NOx. They also contain sulphur, which means SOx emissions, as well as increased particulate emissions as a result of burning solids and liquids rather than gases.
NOx, SOx and particulate emissions all have environmental impacts, and the EEA report assesses how the adoption of renewable energy has affected various environmental measures beyond GHG emissions in the period 2005-2018.
The EEA points out that with combustion-based power generation still dominating the EU power mix, the electricity sector remains a significant source of eutrophication, particulate matter formation, acidification, freshwater ecotoxicity and land occupation. Eutrophication occurs when there is a release of excess nutrients into the environment which stimulates biological growth on an unsustainable basis. As the plants grow, all the nutrients are used up and the overgrown ecosystem collapses, a well-known example being algae blooms. The report found that renewable energy has contributed significantly to reduced eutrophication.
Land acidification is a detrimental side effect of the release of SOx and NOx from fossil fuel combustion. Again, the EEA report find substantial reductions in acidification, owing to renewable energy generation replacing fossil fuels. There was also a large improvement in particulate matter formation when measured against the report’s baseline case. Combustion releases very small particles into the air, less than 10 micrometres in diameter, which get into the lungs of animals and humans. Particulate pollution has been linked to a range of serious heart and lung conditions.
However, there are trade-offs. The report notes that renewable power in general requires larger amounts of metals and other minerals per unit of electricity generated compared with fossil fuels and environmental impacts do arise from the production of some renewable energy technologies. For example, the EEA found that freshwater ecotoxicity rose between 2005 and 2018 versus the baseline case. This is attributed mainly to the mining and smelting operations needed to produce the metals and minerals used in solar panels, and the production of chlorine from the purification of solar-grade silicon, but there are other significant contributors such as the incineration of biodegradable municipal waste.
In addition, there was an increase in land occupation, again relating mainly to solar PV farms and increases in biomass use. These trade-offs must be addressed, the EEA argues, given that to meet the EU’s climate change targets, the use of renewable energy needs to rise to over 80% of all EU power generation by 2050.
The argument in part comes full circle. Solar panels need electricity and heat to be produced and if all this electricity and heat were produced from renewable energy sources, the total environmental impact of solar panels would be even better. Moreover, more renewable energy generation would allow hard-to-decarbonise areas of the economy, such as mining and smelting, to reduce their GHG emissions through electrification, again improving the carbon footprint of renewable energy infrastructure.
More efficient solar cells using less material would also reduce the environmental impact of their production supply chains. Such technologies are on the way – for example tandem perovskite solar cells. And more recycling would reduce demand for the production of raw materials in the first place. Similarly, biomass burning impacts could be addressed by the use of biomass fuels which use less land, but also by better emissions abatement technologies at the point of combustion, the report argues. Overall, the impact of renewable energy has been highly beneficial, contributing to a greener, cleaner world, according to the EEA, even without considering their core purpose, the reduction of GHG emissions.
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