Sunlight is the greatest life-giving force on our planet. It is also a potential source of more clean energy that we can ever use.
The amount of solar energy reaching the surface of the Earth is estimated to be a staggering 3.4 million exajoules (EJ) a year. To give you some idea of how much this is, a single EJ is one quintillion (one million trillion) joules (the Tōhoku earthquake and tsunami measured in at 0.175EJ).
The sun’s rays bathing the Earth in a single year are enough to supply humanity, at its current rate of primary energy consumption, with energy for 7,000 to 8,000 years. That means that capturing just a minuscule fraction (less than 0.1 percent) of this abundance could theoretically cover all our energy needs. It is little wonder that solar energy has created such a buzz of excitement. It is “free”, clean, green and is in absolutely no danger of running out for the rest of human existence.
However, numerous economic, political and technical barriers stand in the way of tapping this apparently boundless resource. One largely neglected factor is land. Most people do not think of land as a constraint on our ability to exploit this manna from the heavens. But solar installations are so space-hungry that switching large proportions of our electricity supply to solar power would occupy enormous swathes of land.
Just how much is not really known because official statistical reporting and models assume the land use of solar installations to be negligible and, hence, exclude this factor. To fill this knowledge gap, a new study, produced as part of the European Union-funded Locomotion project aimed at producing environmental policy models, estimates that the land requirements for solar energy are far from negligible.
Focusing on the EU, Japan, South Korea and India, the simulation forecasts that, in a scenario where 80 percent of electricity is extracted from the sun by 2050, solar installations would require as much as 5 percent of the total landmass (in the case of Japan and South Korea).
In the EU, the land requirements would reach up to 2.8 percent of the bloc’s total territory. To give you an idea of the scale of this, an estimated 4 percent of EU land is currently covered with man-made surfaces, such as cities, towns, villages and roads and other infrastructure required to sustain them. “If at least half of the produced electricity comes from solar power. Land for solar would amount to over 50% of the current EU urban land, over 85% for India, and over 75% in Japan and South-Korea,” the paper observes.
“This huge demand for land will not help the renewable transition,” Dirk-Jan Van de Ven of the Basque Centre for Climate Change (BC3), the lead author of the study, said. “Land occupation usually has several negative side-effects, and the aesthetic impacts will be noticed by many, potentially affecting public support for such a transition,” he added.
These environmental side effects can be both direct and indirect. Potential direct impacts include the conversion of arable land and the fragmentation of ecosystems. Indirect effects include the relocation of activities displaced by solar installations to other locations, such as forests and other biodiversity-rich areas.
Rather like the proverbial butterfly effect, our scramble to capture the sun’s energy could set off a chain reaction that travels from urban areas to reach as far away as the rainforests. For example, if we convert productive land in Europe to solar parks, this may lead to other agricultural and economic activities shifting to other locations, leading potentially to deforestation within and outside Europe.
Given the difference in the productivity of arable land in different parts of the world, this could potentially involve a magnifying effect, indirectly leading to the loss of more land (and more biodiverse areas) than that which is directly converted to solar installations. “Relatively high crop productivities in the EU, Japan and South Korea mean that the displacement of cropland from these regions to regions with lower crop productivities would indirectly increase global cropland cover, amplifying the impact of solar energy expansion in these regions on global land competition by up to 22%,” the study notes. “For every 100 hectares of solarland in the EU, we find that, depending on the solar penetration level, 31 to 43 hectares of unmanaged forest may be cleared throughout all the world.”
In addition to causing possibly irreversible biodiversity loss, the changes in land use are likely to result in emissions that are currently unaccounted for. These include the direct effects on the carbon absorption capacity of the land occupied by solar installations, as well as the indirect effects on the land taken over by displaced activities.
“In the absence of land management practices specifically aiming at carbon sequestration, land cover change due to the expansion of solar energy in the EU would cause 13 to 53g of CO2 per produced kilowatt-hour (kWh) of electricity, about 4% to 16% of the CO2 emissions from natural gas-fired electricity,” the study estimates. Although this is considerably lower than the emissions from fossil fuels, it could still affect the EU’s ability to achieve its net zero emissions ambition. Moreover, this only takes account of emissions from land use changes. The production and installation of solar technology, like other renewables, involves additional emissions and other forms of environmental impact, such as the pollution and deforestation caused by mining the required minerals.
None of this means that we should not transition to solar power and other forms of renewable energy. However, we must proceed with caution. One example of suitable land for solar installations are deserts, which are home to abundant sunshine and little biodiversity compared with, say, forests and arable land. However, aside from some arid and semi-arid areas in southern Europe, there are no real deserts to speak of in Europe.
For decades, the idea has been floated that relatively small areas of the Sahara desert could be used to harvest enough solar energy not only for local consumption but also for export to Europe. “We considered including deserts in our study (for Europe), but finally decided not to, as the additional challenges in terms of construction, interconnection and last but not least, energy security, are so immense that we should question its realism,” maintains Van de Ven.
And the challenges are huge. Transmitting electricity over such vast distances is costly and difficult. In addition, unless capacity is boosted enormously, exporting solar energy from North Africa to Europe would effectively mean less renewable and more fossil fuel power for local consumption, which would leave the global picture largely unaltered. Even trailblazer Morocco, which has invested heavily in solar infrastructure, including concentrated solar energy that can be stored in salts, generates only a fraction of its energy needs from solar power.
It is small wonder, then, that Desertec, the most ambitious initiative to generate and transmit solar energy from North Africa to Europe, as well as for local consumption, has failed to live up to its stated ambitions. This demonstrates why it makes sense, even in sunny climates, to move away from centralised solutions and locate solar power installations as close as possible to the final consumption points. The issue then becomes one of how to ensure that the space occupied by these installations is not damaging to the environment, either directly or indirectly. “When using either cropland or pastures for solar energy, which is probably inevitable in many places when decarbonising the energy system, there are ways to integrate solar energy into such agricultural systems instead of clearing them prior to the construction phase. Although such integrated practices are not common nowadays and may be technically more complex, they could avoid many of the negative impacts from solar energy land occupation,” Van de Ven says.
At present, solar parks tend to be cleared of vegetation, with gravel often placed on top, and solar panels installed close to the ground. Instead of this destructive practice, solar panels should be elevated above the ground and vegetation left to grow underneath. In addition, when it comes to arable land and pastures, the previous function of the land should be maintained as much as possible, for example, by allowing sheep or cows to continue to graze around the solar installations.
The difficulties and adverse effects associated with generating solar power and other forms of renewable energy also imply that we must also focus on demand-side issues, not just supply. For our renewable future to be truly sustainable, we need to find ways of rationalising and reducing our energy consumption.
Solar power and other renewables are the most sustainable forms of energy we possess. However, they are only sustainable if we harness them sustainably.