Renewable supergrids had their moment in the sun – sadly, more metaphorically than literally – in the early 2000s, when Desertec fever was at its height.
The notion of a network of long-distance, high-voltage lines ferrying renewable electricity far and wide – from North Africa to Europe, in the case of Desertec – aligned perfectly with the optimism of those pre-Copenhagen, pre-financial crisis times. Deserts and tundra, mountains and coastlines: all were to be harnessed in the fight against climate change.
Potential supergrid linking renewable power plants in Europe, North Africa and the Middle East. Credit: Desertec Foundation
There is something deeply appealing about supergrids. Their scale and ambition hark back to a time – think of the Marshall Plan or the Apollo Programme – when changing the world for the better seemed like a plausible objective. Fossil fuels have their gas pipelines and coastal terminals (which are genuinely impressive engineering achievements), so why shouldn’t renewables aspire to have continent-spanning infrastructure too?
This isn’t to understate the risks and challenges associated with supergrids. Like all megaprojects, they are vulnerable to cost over-runs, corruption, political meddling and, above all, inflated expectations.
But they at least embody a willingness to believe that such problems can be overcome.
And nor are supergrids merely a means of conveying renewable power from where it’s generated to where it’s needed.
The output of solar, wind and wave power plants can vary considerably – and, crucially, unpredictably – over a range of timescales (seconds, days, months), making the job of matching supply and demand considerably harder. Allowing grids to export power at times of surplus and to import power at times of deficit facilitates the smooth running of the grids as well as safeguarding renewable investments (no need for enforced curtailment) and ensuring uninterrupted power to consumers. A geographically larger grid also serves to ‘average out’ power fluctuations: overcast skies in one location may be compensated for by sun or wind in another.
In the context of an ‘electrify everything’ climate strategy, then, enhancing grid stability through international interconnections is clearly a sensible step. It’s by no means the only step: fit-for-purpose grid codes, appropriate policy and regulatory environments, and sophisticated real-time grid management are all vital. But interconnection beats autarky as far as renewable power is concerned.
Look beyond the hyperbole, however, and the reality of supergrids is somewhat more prosaic.
First, there are degrees of interconnection. An ‘internationally-connected’ grid can be international by virtue of just one connection.
For example, the grids of Spain and France are interconnected, but only by a single, 65 km underground cable capable of carrying 2.8 GW. This is far below the 10 GW minimum stipulated by the EU and has been a perennial problem.
The limited interconnection between Spain and France was one of the reasons, admittedly alongside many others (some of them rather more fundamental), that Desertec failed: the renewable power generated in North Africa would have accumulated in Spain, a country awash in its own domestically-generated solar power, with little prospect of onward export to northern Europe.
In similar vein, the ASEAN Power Grid (APG) is, despite the grand name, currently little more than a series of uncoordinated bilateral electricity exchanges between neighbouring countries. Multilateral power trading will have to await upgrades to national transmission grids, notably in Laos, Cambodia and Myanmar, as well as undersea connections between Indonesian islands.
Furthermore, just having the physical infrastructure in place to trade electricity with neighbours doesn’t mean countries actually do so. As today’s modest levels of electricity exchange in North Africa attest, decades of interconnection can come to very little if regulatory misalignments and political suspicions intervene.
Transmission technology is undeniably improving. Transmission voltages – and hence transmission efficiencies – are increasing: the first 1,000 kV AC transmission line was installed in China in 2009. There are now over 120 operational high-voltage direct current (HVDC) lines worldwide, carrying more than 260 GW of power.
But it’s fair to say that the grand vision of a global supergrid is some way off.
Possible structure of a global supergrid. Credit: Chatzivasileiadis et al
Second, and more pertinent to a discussion about climate mitigation, interconnecting electricity grids is nothing new.
The Russian Integrated Power System/Unified Power System (IPS/UPS), which covers 8 time zones and 15 countries, was started in the 1950s. The synchronous grid of continental Europe, ENTSO-E, which serves 36 countries, owes its origin to the UCPTE, founded in 1951. SIEPAC, covering 6 Central American countries, was conceived in the 1980s. Even Africa, which has the lowest rates of electrification in the world, boasts 5 regional power pools, the earliest of which – the Southern African Power Pool (SAPP) – was established in 1995.
It is important to recognise that these supergrids were not created to serve the interests of renewable energy.
The IPS/UPS, for example, has a generation capacity of 350 GW. Of this, only about 20% is made up of renewables.
ENTSO-E is undeniably greener: renewables account for almost half of its 1,200 GW capacity. (But, of course, a lower fraction – approximately one-third – of actual power generated, due to the generally lower capacity factors of intermittent renewables). Hydro-power plays a prominent role, accounting for almost half of renewable power, with wind accounting for a further 30%.
But much of this renewable capacity has been added in the past 10 years. The ENTSO-E grid long pre-dates the ramp-up in renewables; as recently as 2010, half of ENTSO-E power came from fossil fuels.
Similarly, almost two-thirds of SAPP generation capacity is supplied by coal.
Supergrids are, in short, by no means synonymous with renewables.
Amidst the excited chatter about potential supergrids such as the North Sea Offshore Grid, CASA-1000, Gobitec and the Belt and Road Initiative (BRI) grid, it pays, therefore, to approach with caution.
Some of these supergrids may receive financing and may materialise. Some may catalyse genuinely transformational levels of investment in renewable energy.
Some, however, may not. Some may even perpetuate reliance upon fossil fuels.
So, by all means, let us cautiously embrace super-grids. Let us embrace the scale and ambition that underlie supergrid thinking: without such vision, our climate mitigation efforts will ultimately fail.
But, above all, let us acknowledge that supergrids are not always so super. As far as electricity transmission is concerned, the medium is not the message.