Continental power: operating the Super Grid

Much talk has been made of the merits of smaller decentralised grids but that hasn't stopped the European Commission pouring €86m into the French SuperGrid Institute, a body set up to explore the potential of mass energy networks. As momentum builds behind the concept of continent-wide grid, which many believe offers the strongest chance of achieving mass decarbonisation, we look at how a Supergrid might operate.

european supergrid

By 2050, the European Union has the objective of cutting its carbon emissions by at least 80% below 1990 levels, with an upper aim of 95%. For its part, the power sector is expected to slash its carbon emissions by at least 93% in order for the objective to be achieved. That will require member states to deliver a monumental shift away from carbon intensive power generation methods in favour of renewables. The role of coal, oil and natural gas must increasingly be complemented by wind, nuclear, solar, hydroelectric, and any low-carbon technologies that develop along the way.

Solar farms will spread and wind turbines, particularly those located offshore, will become a far more common sight on Europe's landscape. Power generation is only half the battle. Successfully achieving the ambition will also require a sea change in how electricity is managed, stored and transmitted.

Crossing the continent

The prime candidate for delivering this is to establish a Supergrid across the continent that connects the country level networks together, while also linking up with offshore wind farms and other renewable energy infrastructure to enable the free flow of electricity across Europe. With the recent decision from the European Commission to allow France to provide state aid of €86.6m for the development of technologies for the Smartgrid, this is even more of a reality.

Conceptually, a Supergrid is no different to a National Grid, transmitting electricity from power generation assets to where it is consumed. But in practical terms, the size and scale, not to mention the need to build a huge network of subsea power cables, creates a number of unique technical challenges and benefits.

Moving from AC to DC

In order to serve the transmission needs of the European Union, the grid would be required to transmit huge amounts of power in the order of several gigawatts across distances of several thousand kilometers. Transmission on such a scale is not realistic with the conventional approach of Alternative Current (AC) transmission technology, as global consultants PWC explained: "Because it is based on AC technology and because of congestion at the national borders, the grid is currently not strong enough to generate the benefits of a Super Grid, although the power system stretches over a large enough area."

With its carbon capturing components and coal displacing capabilities, biomass is a policymaker's carbon cutting dream.

Instead, the bulk of the transmission would need to be carried out through Ultra-High-Voltage-Direct-Current (UHVDC) cables, which are currently used to transmit offshore wind power to shore. Capable of handling up to one million volts and less prone to transmission loss over long distances than AC networks, UHVDC offers the strongest chance of making the Supergrid feasible, both operationally and economically.

"Based on the current generation of HVDC, and with current cable technology development rates, we are confident that the residual technology gaps will soon be closed to make the European supergrid a reality," explained Peter Jones, engineering manager grid systems at ABB UK.

Smoothing out intermittency

While continental scale presents significant challenges on the transmission front, it may serve to mitigate the impact of issues of the intermittency common to various types of renewable energy generation. In a solely national system, the ability to generate power from wind turbines or solar panels relies on a country's weather.

However, with a grid connecting the entire continent, a country would be able to draw power from wind or sunshine in another country. Through the Supergrid, individual weaknesses could be overcome by collective strength.

"The share of wind would be high in the windy North Sea region, the share of solar power high in the sunny south of Europe, whereas the Baltic Sea region and Eastern Europe would be rich in both wind and biomass. The mountainous regions in Scandinavia and the Alps would provide hydro generation and storage resources."

The principle of 'smoothing' is already being applied in the NordLink project between Germany and Norway. Through a connection between the two countries, Germany will offload its excess wind power to Norway and stabilize its own supply with Norwegian hydropower. If effective on such a small scale, the 'smoothing' could strengthen the proposition of the Supergrid significantly.

"The share of wind would be high in the windy North Sea region, the share of solar power high in the sunny south of Europe."

Small-scale decentralized grids will still play a strong role

While the primary objective of a Supergrid would be to enable long-distance transmission of electricity, the full value of the concept can only be realised if it also improves the way the grid operates. Smart grid technology, which has developed rapidly over recent years to improve energy distribution on a local scale, offers the potential further mitigate intermittency and increase energy efficiency. Using a network of sensors and algorithms, the technology maximises efficiency by diverting spare capacity in one sector to where demand is highest.

According to Antonio Battaglini of the Institute for Climate Impact Research, Europe should look beyond a Supergrid to a Supersmart grid: "The large-scale centralised SuperGrid and the small-scale decentralised SmartGrid approaches are often perceived as being mutually exclusive alternatives. However, we argue on the fact that the two concepts are complementary, and can and must coexist in order to guarantee a transition to a decarbonised economy."

The concept is shared by German firm Siemens, which envisages a combination of high capacity cables handling the bulk of transmission and a network of localized smart grids. "With these DC Ultra High Power transmission technologies, the 'Smart Grid', consisting of a number of highly flexible 'Micro Grids', will turn into a 'Super Grid' with Bulk Power Energy Highways, fully suitable for a secure and sustainable access to huge renewable energy resources," it said.

A European energy revolution

The industrial giant suggested that, if successful, a Supergrid with smart grid capabilities could revolutionise the way energy is managed across Europe: "Just as the internet has driven media from a one-to-many paradigm to a many-to-many arrangement, so too will the smart grid enable a similar shift in the flow of electricity."

With transmission capacity continuing to increase - ABB recently launched a 2,600MW capacity cable that loses less than 5% power over a distance of 1,500km - and smart grid technology rapidly evolving, the technological barriers to a European Supergrid appear close to being overcome.

If it is to be taken from concept to reality, though, the most critical factor is strong support from the EU and its member countries, from establishing regulatory standards to ensuring consistency between components and cables, to pushing through plans for a common electricity market,. If member states can pull together and push it through, then the upper target of 95% decarbonisation by 2050 might just be achieved.

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