Renewables are essential to making this happen. The joint energy team of Ecofys and Navigant have investigated Europe’s renewable generation resources and find that offshore wind from the North Seas region will be pivotal for realising a 100% decarbonised electricity supply in less than 30 years.

In their analysis, the experts looked specifically at the ten countries around the North Sea – France, Belgium, the Netherlands, Luxemburg, Germany, Denmark, Sweden, Norway, Ireland, and the United Kingdom – that cooperate in the EU-supported North Seas Countries Offshore Grid Initiative established in 2009.

To determine the required offshore capacity for the whole region, the team started with the 2045 electricity demand per country and assumed a complete phaseout of fossil-fueled electricity generation, as well as a started retirement of nuclear.

We assumed that current operational nuclear plants will be decommissioned and not replaced after their lifetime. Thus, the only nuclear plants around by 2045 will be new ones that are in an advanced planning stage today.

Land-based generation capacity

The Ecofys and Navigant consultants then determined the total available onshore generation capacity by means of several scenario studies and identified how much of the Paris-compatible electricity generation capacity can be met on land.

The countries’ joint onshore generation resources (wind, solar, bio, hydro, and remaining nuclear) could provide up to 55% of the required capacity. This leaves 45% to be covered by offshore sources and translates into an offshore wind target of approximately 230 GW for the North Seas countries.

180 GW of that capacity could be generated in the North Sea, and the remaining 50 GW in other seas like the Baltic and Irish Seas and the Atlantic.

With 13 GW installed currently, however, the region is far from the required total. To realise this growth, the offshore wind installation rate would have to triple from the current 3 GW/year to approximately 10 GW/year in 2030.

Long-term spatial planning

Such growth in offshore wind cannot be realised through individual efforts—it is possible only through a new level of collaboration, coordination, and interconnectivity between the North Seas countries.

In addition to its role as a natural habitat, the North Sea is intensely used as a place for fisheries, tourism, military zones, oil & gas infrastructure, and shipping, and therefore of vital importance to the region’s economy.

While there is sufficient space to develop the required offshore wind capacity (current estimates indicate that some 10% of the North Sea surface will be required for offshore wind, based on a wind farm intensity of 5-6MW/km2), a careful balance must be maintained, ensuring maximum benefit to the environment and cost-efficient development of both wind farms and associated infrastructure.

Harnessing and preserving the environment of the North Sea region requires constructive collaboration among all sectors. The potential offshore grid could support the marine biodiversity through new protected areas for wildlife and extended migratory corridors.

This requires a shared long-term view by all North Sea countries. A joint spatial planning strategy is needed to reflect changes in use (e.g., decommissioning of oil & gas) and ensure a cost-efficient utilization of the resource, aligned with offshore and onshore grid development and environmental protection.

50 GW-80 GW interconnector capacity required

Long-term planning will also have to go into securing the stability of such new infrastructure. With higher shares of renewable energy, the stability of the grid heavily depends on an increase in flexibility options.

A crucial enabler for a flexible power system is a well-developed network, or in the case of the North Sea offshore wind-dominated system, an infrastructure with increased levels of interconnectivity.

Based on a high level adequacy assessment, we determined the likely reliable capacity that would be available. Ecofys investigated peak demand situations for the three sub-systems around the North Sea: Great Britain and Ireland, continental Northwestern Europe, and the Nordics.

The team analysed how much wind power is available at minimum wind conditions with regard to climatic data and the geographical spread of wind parks.

Comparing the results with the available onshore resources, dispatchable generation and flexibility from demand and storage, they deducted the margin each of the three “sub-systems” has. A negative margin shows a need to interconnect to regions with more resources.

The analysis shows that Great Britain and Ireland have a need for import capacity of roughly 30 GW, while continental North Western Europe has a deficit of 25 GW. An overall level of 50 GW-80 GW of interconnection capacity will be required for the North Seas area.

Interconnection capability

Growth of interconnection capability requires a careful evaluation of the cost-benefit analysis approach. A new methodology to value grid stability could incentivize interconnector capacity.

Current planning practice often limits the level of offshore interconnections to save operational costs. Today’s main methodology, approved by regulators and the European Commission, compares the cost for a new interconnector with the carbon and fuel cost savings it will bring about.

After 2030, these savings will be less of an incentive when renewables plants – with zero marginal and no carbon costs – are dominating the market.

Interconnectors, however, will still be crucial as they give flexibility in stressed system conditions and periods of scarcity, and thus provide security of supply.

The current methodology does not express this benefit. The task therefore demands a new way of thinking: business cases will have to be redefined to include societal and environmental profits.

More flexibility options

The transition to a decarbonised electricity supply marks the end of dependence on conventional reserves. This will also mean a significantly reduced dispatchable capacity and calls for a steep increase in flexibility options.

With the phaseout of fossil-fueled electricity generation, the dispatchable generation capacity drops from a level of 64% in today’s generation mix to approximately 25%, primarily from hydro and bio, in the 2045 system.

A transition to new, cost-effective flexibility sources such as storage, demand response, power-to-gas/heat, and ancillary services from renewables is already underway. The use of these new flexibility sources will become essential in the 2045 scenario to ensure a constant, instantaneous supply/demand balance.

This means that a more realistic and robust potential estimate and roadmap are needed than currently available forecasts, to plan demand response, small-scale storage and large-scale storage by 2045.

This should not be based purely on industry-push figures, but also on making the tradeoff of some of these projects with interconnection levels. With flexibility options becoming both more significant and affordable, e.g., the demand for interconnection could go down and in turn further increase the need for flexibility options.

However, before this demand can be addressed on the technical level, it will be the collaborative connection between the involved countries and public and private stakeholders that counts.

Developing a long-term spatial planning strategy and a robust 2045 roadmap for flexibility options will be two of the key steps to meeting the Paris goals. Joint strategic planning will secure operational security during and beyond the energy transition.

****Michiel Mueller (1963) is Managing Director at Ecofys and Ecofys Wind Turbine Testing Services (WTTS) and has been working at Ecofys from 2008. After receiving his doctorate degree in Physical Chemistry from the University of Amsterdam, The Netherlands, in 1990, and several post-doc positions, Michiel Mueller became Assistant professor in 1999 and Associate Professor in 2002 in non-linear optics and biophysics at the University of Amsterdam. During this time he also held visiting scientist positions at two Universities in the USA. Throughout his academic career Michiel Mueller published more than 60 papers in peer review journals and held numerous presentations at international conferences.

In 2008, Michiel Mueller made a major career switch to the field of sustainable energy and became senior Researcher & Developer in the ‘Innovation’ division of Ecofys. He was made responsible for the sea water air-conditioning (SWAC) development programme, which concerns both the technical and financial issues for SWAC project development. Under his supervision financial assessment, SWAC system optimisation and control strategy approaches have been developed and executed.

In addition he has undertaken various initiatives within the innovation field of heat & mass transfer and bio-energy. He was part of the management team of the ‘Innovation’ division. In November 2009, Michiel Mueller joined the Wind Energy department of Ecofys as Senior Consultant, working as project leader for the Far and Large Offshore Wind (FLOW) programme and in 2011 became unit manager of the wind energy unit. He was also involved in business innovation within the wind energy portfolio. Michiel Mueller was one of the project developers of the wind turbine test facility near Lelystad, which became operational in 2011. Michiel Mueller is the Managing Director of Ecofys WTTS which co-ordinates all activities at Test Site Lelystad and provides all required measurement services to the turbine manufacturers. [Utrecht, Netherlands]