BEST PATHS: the EU grid research project that tested five technologies

On 1 October 2014 a research consortium of 39 organisations from 11 European countries began a four-year programme with a long name: Beyond State-of-the-Art Technologies for Power AC Corridors and Multi-Terminal HVDC Systems. Its acronym, BEST PATHS, was the name that stuck. The kick-off meeting was held in Rome on 29–30 October 2014, and the project ran until 30 September 2018. Red Eléctrica de España, the Spanish transmission system operator, coordinated it; Vicente González López of REE was the project coordinator.

The funding came from the European Union’s Seventh Framework Programme (FP7), under the energy call FP7-ENERGY-2013-2. The EU’s project record gives a total cost of €62,802,255, of which the European Commission contributed €35,499,975.65, and in its own communications the consortium described BEST PATHS as the largest research project in the energy field financed under FP7. The work was organised in 14 work packages and 74 deliverables.

The problem it was set up to solve

The case for the project was written in terms of targets. To keep the global temperature rise below 2°C, industrialised countries were expected to cut greenhouse gas emissions by up to 95% by 2050, and the energy sector was to carry much of that cut. Wind power was the main new source: onshore and offshore wind in the EU was projected to pass 190 GW of installed capacity by 2020.

The difficulty was geography and timing. Wind and solar output rises and falls with the weather, and the best sites are often far from the cities that use the power. The project’s own description treated a major development of Europe’s transmission network as essential to keep supply reliable while moving that power over long distances. BEST PATHS set out to develop network technologies that would raise the capacity of the pan-European grid and make the electricity system more flexible, and to prove them at scale.

Its demonstrations had three broad aims: to move from single HVDC lines towards HVDC grids, to upgrade and repower the existing AC parts of the network, and to integrate superconducting high-power DC links into a meshed AC network.

The five demonstrations

Each demonstration was led by an industrial partner and built around one technology.

Demo 1, HVDC links for offshore wind. Led by the Spanish utility Iberdrola, it studied how converters in wind turbines and HVDC substations interact, released an open simulation toolbox and built a laboratory DC grid in Trondheim with SINTEF. The full account is on the page on HVDC offshore wind links.

Demo 2, multivendor interoperability. Led by the French operator RTE with ABB, Alstom Grid and Siemens, it tested whether HVDC converters from different manufacturers can run on one DC system, first in offline simulation and then with the vendors’ real control hardware. See HVDC-VSC multivendor interoperability.

Demo 3, upgrading a multi-terminal HVDC link. Led by Terna, it used the SACOI link between Sardinia, Corsica and mainland Italy to test a new converter, extruded cables for higher voltages and depths, DC overhead conductors and insulators. See upgrading multi-terminal HVDC links.

Demo 4, repowering AC corridors. Led by the German operator 50Hertz, it worked on high-temperature low-sag conductors, insulated cross-arms, a composite tower, dynamic line rating and live-line working. See repowering transmission lines.

Demo 5, superconducting cables. Led by Nexans, it built and tested a 320 kV, 10 kA direct-current cable system using magnesium diboride, rated at 3.2 GW. See the MgB2 superconducting cable.

Around the demonstrations sat an assessment strand, centred on Work Package 13, which scaled the results up to the whole European system: scenarios, cost-benefit analysis, key performance indicators and a study of the barriers to replicating the technologies. Those reports are listed on the publications page.

How the results were shared

Each year the consortium held a dissemination event: Paris on 5 November 2015, Berlin on 26 October 2016 and Madrid on 22 November 2017. Between May 2017 and July 2018 each demonstration also had its own workshop, in Trondheim (11 May 2017), Budapest (5 April 2018), Codrongianos (9 May 2018), Paris (5 June 2018) and La Spezia (5 July 2018). The closing conference, “Renewing the EU electricity grid: the Best Paths towards energy transition”, took place in Brussels on 20 September 2018 and was organised by the dissemination partner Greenovate! Europe; around 120 experts attended.

What it concluded

González López’s own assessment, made as the project closed, was that BEST PATHS had achieved almost 100% of its initial objectives. He pointed to three results: faster development of HVDC grids, through de-risking the use of different converter technologies with wind generation and showing that some interoperability issues could be fixed by adjusting one vendor’s control strategy; validated technologies to add capacity and flexibility by uprating existing AC and DC assets; and the validation of gigawatt-scale superconducting cables.

He also set limits on that claim. BEST PATHS was a demonstration project, he said, and its impact on society would need further work on industrialising and selling the solutions, with some topics needing more research. Antonio Iliceto of Terna, chairman of the consortium, presented a set of recommendations in Brussels on how to replicate the results and overcome the barriers to deploying them.

That caveat has proved accurate. Other EU projects, some running alongside it and some starting later, took up the questions it opened: MIGRATE on power systems run entirely through power electronics, PROMOTION on HVDC protection and DC circuit breakers, OSMOSE on grid flexibility, and more recently InterOPERA on multi-vendor HVDC. The list of partners by country is on the consortium page.

At the Brussels conference González López addressed policymakers, regulators, grid operators, manufacturers, researchers and citizens alike, telling them there was “no time to lose”. The last document on its publication list is dated 6 November 2018.