As renewable energy takes centre stage in energy & climate discourse, Thomas Walsh explores what this means for the electrical grid.
In April of last year, the front page of The Economist presented a striking message to environmentalists: “Hug pylons, not trees”. The often-overlooked electrical grid is the backbone of modern society. Electrification has ushered in pivotal elements of daily life - from light bulbs and smartphones to air-fryers. The humble washing machine has significantly displaced labour traditionally undertaken by women, contributing immensely to gender equality. Refrigeration has transformed nutrition and life-saving incubators and ventilators can offer people a second chance.
Currently, electricity only accounts for 17% of global energy consumption. The rest is primarily shared between transport, industry, heating and steel & cement. Decarbonization pathways are dependent on electrification 2.0 as oil-powered vehicles are replaced with battery-electric ones and boilers are replaced en masse with heat pumps, which instead of burning fossil fuels to release heat, use electricity to efficiently move heat from one place to another. Electrification has elevated living standards for billions and electrification 2.0 will be the single-most important tool in mitigating climate change.
Electrification has elevated living standards for billions and electrification 2.0 will be the single-most important tool in mitigating climate change.
The grid is surprisingly delicate. 50 hertz alternating current (AC) lines dominate the modern grid. The flowing power changes direction fifty times each second, equivalent to three-thousand times per minute, which is the speed at which the turbines in gas and coal plants are rotating, all near-perfectly synchronised and appropriately named ‘synchronous generators’. A 1% deviation is allowed.
The challenge lies in transitioning away from conventional generation to wind and solar, asynchronous technologies. Solar photovoltaics derive electricity directly from photons of sunlight, no moving parts to be found, and while a wind turbine is evidently spinning, it is rotating with the wind, not in tandem with the grid. Wind turbines, solar photovoltaics and batteries mostly feed power into the grid today with the help of ‘grid following’ technologies called inverters. These inverters convert the power from these sources into AC power, matching the grid frequency. At high levels, this can be destabilising. If the frequency falters, grid-following devices attempt to follow it and risk pushing the frequency too far in the wrong direction. Promising but nascent ‘grid-forming’ inverters will not only solve this issue, but possibly make the new system more resilient than the old one.
Promising but nascent ‘grid-forming’ inverters will not only solve this issue, but possibly make the new system more resilient than the old one.
One technology attempting to maintain the useful aspects of fossil-fuel generators without the emissions was recently installed in Ireland. On the site of the soon-to-be decommissioned coal plant ‘Moneypoint’, the world’s largest synchronous compensator has been installed. The synchronous compensator is essentially a spinning turbine that is not actually producing or consuming power, but due to its huge weight and speed, has enough kinetic energy that if anything goes wrong on the grid, its inertia can keep the grid stable temporarily.
A pledge to triple renewable capacity by 2030 emerged from COP28 in Dubai. While countries like Sweden, France, Brazil and Canada have long-ago achieved low-carbon grids thanks to a combination of fortunate geography suited to large hydropower dams and support for nuclear power, the rest of the world is scrambling to renovate its grids to accommodate growing shares of renewables, often located in remote locations. Ireland faces delays of over 12 months in connecting solar farms and electric vehicle (EV) charging stations to the grid. Onshore wind projects face similar difficulties, offshore farms will be even harder. European and American grid infrastructure is old and grid construction has been dormant for decades. Expanding the grid may be much harder in the West than in China and India, where rapid expansion of access to electricity in recent decades mean that there is a workforce ready and a regulatory environment that promotes critical infrastructure and doesn’t heed to NIMBYism.
While countries like Sweden, France, Brazil and Canada have long-ago achieved low-carbon grids thanks to a combination of fortunate geography suited to large hydropower dams and support for nuclear power, the rest of the world is scrambling to renovate its grids to accommodate growing shares of renewables, often located in remote locations.
An extensively interconnected European supergrid is often floated as a solution to the issue of variable renewable energy. The grids of Ireland and Great Britain, for example, are already connected via subsea cables. However, due to the proximity of the two islands, when wind speeds are low in Ireland they are also low at its neighbour, hence they cannot help one another. The Celtic interconnector will link Ireland to mainland Europe via France, and future sea-floor wires may allow Ireland to trade electrons with Spain and Belgium. Greater distance means that both countries are less likely to experience the same weather patterns. In a European supergrid, spanning from Ireland to Estonia, a drought in Portugal resulting in lower hydropower can be compensated by importing Spain’s wind power, while Spain is purchasing French nuclear power, while France is in turn importing German solar power.
Revolutionising this continental interconnection is the comeback of direct current (DC) power. While AC is generally preferred, DC becomes more economical for distances exceeding five-hundred kilometres, or a mere fifty kilometres for submarine cables, thanks partly to DC’s benefit of suffering fewer power losses. The same technology enabling Ireland to plug into the Continental European Synchronous Area (CESA) is allowing China to connect its population centres to remote solar farms in the desert and wind farms in Inner Mongolia.
British company Xlinks is building four subsea cables that will take power from Morocco before travelling a record-breaking 3,800 km around the coasts of Spain, Portugal and France and finally connecting into the UK national grid. The cable should be mutually beneficial, with Morocco profiting from the exports while the UK will receive as much as 7% of its electricity from solar power in much sunnier Morocco. Morocco, however, has yet to build the promised wind and solar at the production end of the line.
Balancing supply and demand in a system dominated by variable renewables is dependent on greater flexibility. It involves ‘demand response’, whereby electricity consumption is shifted to periods where renewable generation is strongest and prices are lowest. One such innovation is vehicle-to-grid charging, wherein an EV plugged into a charging station will be able to feed electricity back into the grid for short periods to help smooth out the peaks and troughs in supply. Smart heating systems will similarly be able to switch on and off.
In 2050, envision a world where many countries boast smart, seamlessly integrated grids combining electricity, transport, and heating. It would be transformational, but also raises the stakes. A temporary grid failure (increasingly vulnerable to cyber attacks due to increased digitisation) in such a system could lead to widespread economic disruption. A black-out would leave households in the cold and both private and public transport out of order. Additionally, the transition isn’t without financial hurdles. Almost a third of Irish electricity bills go towards network expansion and maintenance climate-friendly measures such as grants and tax-breaks for rooftop-solar run the risk of being heavily regressive if homeowners are the only ones to benefit and renters are yet again, at the wrong end of the stick.