Weekend Argus (Saturday Edition)
Is green energy really green?
THE accelerating impacts of climate change and the need to move away from fossil fuels has cast a new light on the world’s energy systems.
Regardless of political stance, it is clear that the world and South Africa are in the process of transitioning to a new energy economy.
Global advocacy for low-carbon economies means shifting away from fossil fuels entirely, even while electrification of everything feasible places increased demand on national grids.
Providing adequate energy is a critical backbone for modern society: given that the maximum sustained effort a person can put out is roughly 75W, a single barrel of oil is roughly equivalent to 11 years of sustained human effort at 40 hours a week.
It’s evident that we cannot go back to pre-fossil fuel energy levels but at the same time, the transition to emissions energy is essential for human survival.
The increasing role of intermittent renewable energy (RE) sources, particularly wind and solar, also means that energy storage will play a key role going forward.
This entails a massive expansion in batteries for storage as well as grid expansion to reach new areas, and a consequent shift in the supply chains and industry to manufacture the new technologies on a massive scale.
Provision of energy is never clean. Obtaining, moving and burning fuels is messy, dangerous and the main driver of climate change as well as having huge impacts on landscapes, water and air quality.
Similarly, delivering energy for the modern world – from firewood, through coal and oil, to non-combustion technologies like nuclear, wind and solar – there is always a resource footprint to be considered. Nevertheless, there are three key differences that RE brings to the table.
First, technologies such as wind and solar do not have ongoing resource extraction requirements for fuel. Once installed, the technologies can provide power for the lifetime of the infrastructure, with minimal maintenance costs.
Second, they are massively more efficient. The total energy returned at the point of consumption, compared to the energy invested, is much higher for the products because no fuel is required. Compare this to combustion products which typically waste a minimum of 70% of the primary energy (except where used for direct heat), as well as effectively a similar proportion of all the energy invested in obtaining the fuel.
Finally, renewable energy technologies have massive recycling potential. The materials used in batteries, solar panels, magnets, construction and transmission can be taken from end-of-life products and reused in most cases. This opens the potential for development of a more circular economy in the energy sector, which is almost exclusively a linear flow.
Are there any drawbacks to renewable technologies?
Making use of them will require a massive change in how energy is provided – electrifying almost everything from road transport, industrial processes, heating and cooling, and using electricity to manufacture interim products such as green hydrogen to address hard-to-decarbonise sectors. While it is cheaper to do so than continue to use 20th-century technologies, it would be a costly and incremental process.
Second, there is a resource footprint associated with securing all the minerals needed for a global roll-out of the technologies. Different minerals are needed in unprecedentedly high amounts from those we use, which means an expansion in mining in different areas. Regulation of mining to better enable local beneficiation and reduce the environmental impacts is essential.
However, despite some erroneous calculations from some observers, the International Energy Agency’s net zero energy scenarios entail a relatively moderate growth in the resources, and indicate that known global reserves are more than adequate for the demand. Fossil fuels production currently requires the extraction and moving of 15 billion tonnes of material a year. The current total for all metals is less than half of that, including all the iron used in construction.
The IEA estimates that critical materials demand might reach four times current production. Allowing for the large amount of potential substitution (such as aluminium for transmission in place of copper) and the replacement of fossil fuels, the mineral demand to produce energy would shrink by as much as 90%.
Third, the spatial footprint of the technologies is not inconsiderable. PV farms take up space, as do wind farms. Unmanaged, expansion of RE could significantly impact on natural areas, and potentially agricultural land as well.
This is why strengthening the distribution grid in cities to prioritise rooftop solar is a critical mitigation measure. In addition, wind energy is compatible with agriculture of various types, and interplanting of crops in solar farms – termed “agrivoltaics” – may enhance yields and reduce water loss, particularly under conditions of climate change.
Moreover, the spatial footprint for full RE replacement of current energy demands is lower than the extant footprint of the full fossil fuel supply chain (mines, dumps, powerplants, pipelines and other infrastructure, implying that there is scope for remedying post-mining areas through repurposing and rehabilitation.
A shift away from our energy systems cannot be haphazard, but requires systems of governance to ensure that we do not repeat the mistakes of the past.
“Green energy” technologies are not a free lunch, but they do open the potential to reduce our rate of consumption of natural resources and our impact on natural systems on which modern civilisation depends.