Integrating renewables into the electricity grid


This article is part of our special report Wind Energy.

Europe has put in place legislation to promote renewable energies but is now faced with the challenge of integrating increasing amounts of intermittent power sources like solar and wind into the electricity grid, running the risk of destabilising it.

The EU's 2001 directive on the promotion of electricity from renewable energy sources established a framework for integrating renewable energies into Europe's grid. The directive required member states to take measures to ensure that transmission and distribution system operators "guarantee the transport and distribution of electricity produced from renewable energy sources".

Acknowledging persistent large variations in the degree of integration achieved by member states, the framework was strengthened in the EU's new Renewable Energy Directive, agreed in 2008.

The law requires member states to provide either priority or guaranteed access to the grid for electricity produced from renewable sources in order to achieve the objective of producing 20% of Europe's energy from renewable sources by 2020.

Furthermore, it obliges EU governments develop grid infrastructure, intelligent networks and storage facilities in order to secure the operation of the electricity system while ramping up production of renewables.

In addition, many countries have put in place national incentive schemes to accelerate the grid integration of renewables, such as feed-in tariffs in Germany and other countries (see Euractiv LinksDossier on 'Supporting renewable energies').

The EU's 2020 renewable energies goal means that the share of renewable electricity will have to rise to 34% by 2020. Moreover, the long-term drive towards a low-carbon economy by 2050 necessitates aggressive de-carbonisation of electricity supply.

The EU's 2020 renewable energies goal means that the share of renewable electricity will have to rise to 34% by 2020. Moreover, the long-term drive towards a low-carbon economy by 2050 necessitates aggressive de-carbonisation of electricity supply.

The integration of large amounts of renewable electricity will, however, require massive upgrades to the electricity grid, which was designed at national level for large-scale centralised production. New interconnections and intelligent systems will be required to handle decentralised, intermittent power sources such as renewables.

New interconnections

The challenge of integrating large volumes of renewable energies into the grid hinges on their intermittent nature and uneven geographical distribution. For instance, the best wind energy potential is located in the north during winter, while solar radiation is strongest in the Mediterranean area during summer.

Major development of the European grid infrastructure is thus considered critical to maintaining reliable power supplies and bringing renewable energy from production sites to consumers.

Missing interconnections have been identified in many European regions, preventing greater penetration of renewable energies. Connecting Spain with France, for instance, would allow solar energy to be brought from the Iberian Peninsula. Other priorities include connecting the UK and Ireland with France or the Baltic states with continental Europe.

As for post-2020 scenarios, a high-voltage cable from North Africa is in the pipeline to transport solar electricity from sunny deserts to Europe, which is the intention of projects like Desertec and the Mediterranean Solar Plan.

Moreover, the development of offshore wind farms in the North Sea and the Baltic Sea requires significant investment in offshore grids. European offshore wind capacity could increase to 40GW by 2020, predicts the European Wind Energy Association (EWEA).

Blueprints for a North Sea offshore grid have been developed in several studies, and the European Commission is working on its own plan. North Sea countries agreed in late 2009 to cooperate on developing a North Sea grid that could cost up to €30 billion, according to EWEA estimates.

The ultimate vision is a European 'supergrid' to provide supplies of renewable energy throughout the continent by tapping into vast solar resources from the Mediterranean and wind from the North.

Backing up: Investing in storage

Committing to a large proportion of renewable energies also poses a challenge to maintaining the reliability of Europe's power supply system at the current 99.97% standard.

Variable generation from solar or wind has traditionally been backed up with fossil fuel and thermal plants. But concerns have been raised that this could negate at least some of the CO2 savings achieved by clean energy production and lead to losses, as traditional power stations cannot simply be switched on and off according to when the sun shines or the wind blows.

Possible solutions include storage, grid development and demand-side management via smart grids and smart meters.

Storage technologies will have a role to play in bringing more flexibility to the system while cutting resource losses, as they allow surplus energy to be used later, for example when wind is low. There are many potential options, including pumped hydro storage, compressed air, district heating systems and batteries in electric vehicles.

Using electric vehicles as storage systems will most likely only be available after 2020 when electric cars have taken off and smart grids have become the norm.

The technology is available, but substantial investment will be required to make storage available on the scale required. However, there are currently few incentives for investors to develop storage capacity, according to experts.

On the other hand, an integrated European network that is capable of transporting a mixture of renewable sources can balance the load. The idea is that a diversified portfolio of renewables – wind, solar, biomass or tidal – can help reduce peaks in the transmission system. For instance, low wind periods in Northern Europe could be compensated by solar power from the south during summer time.

Smart grids

The development of intelligent grids at local distribution level will be crucial to reducing peaks in electricity demand, in order to ease pressure on the grid and increase its capacity to host renewable and distributed electricity sources.

So-called smart grids are expected to transform today's power distribution systems, which are designed for centralised production and one-way transmission, into flexible, interactive, bidirectional systems that distribute electricity more efficiently.

Upgrading grids with information and communications technologies will also allow consumers to track their energy use in real time with smart meters. Coupled with automated household appliances, this could help shift demand towards off-peak times, for example during the night.

All these improvements are expected to ease pressure on the grid and reduce the need to invest in grid reinforcement and back-up capacity. They will be particularly important because electricity demand is expected to increase as transport and heating systems become more electrified.

In addition, consumers will be able to become renewable energy producers by selling energy produced by rooftop solar panels, for example, back to the grid. Smart grids will also help avoid congestion created by small-scale renewables.

Moreover, intelligent networks will allow new users to emerge. Scores of electric cars connected to the grid could eventually be used to store energy.

Feasible and affordable?

Several studies have recently taken stock of the feasibility of moving to a renewables-based economy by mid-century.

Arguably the most comprehensive analysis to date of the cost of shifting to low-carbon power generation was published by the European Climate Foundation (ECF) in April 2010. It showed that Europe could meet at least 80% of its energy needs with renewables by 2050 without paying more for electricity than it would by continuing with the current fossil-fuel based infrastructure (EURACTIV 14/04/10).

The ECF estimates that an 80% share of renewables would require Europe to spend €2,860 billion in capital investment in new power plants, additional grid and back-up plants between 2011 and 2050. On top of this would come €5,705 billion in operational expenditure, including fuel costs, non-optimal plant use and storage losses.

But the total cost of €8,565 billion would be almost equal to the business-as-usual scenario, in which less money would have to be spent on new infrastructure but the cost of operating it would be higher.

In the long term, the cost to the economy of a low-carbon shift would actually be lower, as shifting away from oil and gas - as well as the increased energy efficiency - would reduce the cost of energy per unit of gross domestic product and thus reduce Europe's energy bill, the study forecast.

The foundation's findings were confirmed by another study conducted by PricewaterhouseCoopers in March 2010. It argued that it is both economically and technically feasible to produce all of Europe's electricity from renewable sources by 2050 via an interconnected EU-North African power market.

In its communication on financing the Strategic Energy Technology (SET) Plan, the European Commission called for Europe's energy research budget to be tripled to support the transition to a low-carbon economy. It earmarked billions for wind, solar and bioenergy research as well as for developing smart grids.

"Increasing smart investment in research today is an opportunity to develop new sources of growth, to green our economy and to ensure the EU's competitiveness when we come out of the crisis," said former Science and Research Commissioner Janez Poto?nik.

Commenting on the agreement between North Sea countries to cooperate on an offshore grid, Irish Energy Minister Eamon Ryan said the project was a prime example of "European vision and ambition in energy policy".

"It is a huge step towards meeting our common renewable energy goals and in guaranteeing a low carbon future. Irish wind farms will be able to connect directly to Europe, not only securing our energy supply but allowing us to sell the electricity produced on a wider market," he said. "It makes economic as well as environmental sense. By working together, all of the countries involved will reap the benefits."

Spanish State Secretary for Energy Pedro Marín Uribe pointed out that a significant portion of intermittent renewable energy in Europe's energy mix will require substantial regulatory changes as well as investment of capital into managing the electricity system.

"This type of manageability is very difficult to tackle in small systems, but as larger systems are considered, this difficulty is reduced thanks to the diversification of technologies, as well as geographical weather and climate conditions," he said.

"Therefore the energy model of the future cannot be based, like in the current one, on self-sufficient, national systems with some poor interconnections with limited capacity," he added, arguing that moving to an electricity system with a European dimension is inevitable.

The European Network of Transmission System Operators for Electricity (ENTSO-E) argues that the integration of renewable energies into the grid is one of the principal drivers of investment in electricity infrastructure, along with market integration and security of supply.

"This implies, for example, not only putting cables into the North Sea to bring offshore wind energy to shore but also lines to transport that electricity into the countries, to the load centres," said Konstantin Staschus, ENTSO-E secretary-general.

The European Photovoltaic Industry Association (EPIA) pointed out that technical limits to the penetration of photovoltaic solar and other renewable energy sources will depend on the evolution of the generation mix in place and the "smartening" and strengthening of distribution and transmission infrastructure.

"The daily and seasonal variations of PV generation across geographies present a challenge and require increased flexibility of grid management and of the generation mix, as well as grid-integrated power storage capacity. Increased flexibility in the generation mix will only be possible through better coordinated long-term planning of investments in new generation capacities (additional and replacement) across the European electricity market," it argued in its 'SET for 2020' study.

The European Wind Energy Association (EWEA) said that existing and planned European offshore wind projects would cover 10% of Europe's electricity needs, but a lack of grid infrastructure and liquidity problems would prevent the development of some.

"We really need to develop an entire new industry," said Christian Kjaer, EWEA chief executive, pointing out that offshore wind requires radically different infrastructure to its onshore counterpart.

Eurelectric, the European electricity industry association, argued that grid investments are the key enabler that will allow electricity markets to cope with large volumes of intermittent renewable energy. It argued that this will not only affect distribution and national transmission networks, but also transmission networks in adjacent and more distant countries.

"Hence the focus on investments should be shifted from a national to a regional and pan-European perspective. First of all, this requires top-down grid planning on a European scale, followed by significant and prompt investments to increase cross-border trading," it said in a statement.

The European Renewable Energy Council (EREC), an industry group, argued that the EU could cut its emissions by more than 90% by 2050 by producing all its energy from renewable sources. It predicted that the largest increase would take place in renewable electricity, driven by wind and photovoltaic (PV) solar, complemented with a take-off in renewable heating and cooling from biomass, solar thermal and geothermal applications.

"Higher upfront investment for renewable energy does pay off in the long-run as the capital investment cost will be outweighed by the avoided fossil fuel and CO2 costs," said EREC President Arthouros Zervos.

The European Climate Foundation (ECF) argued that the necessary ingredients for reaching Europe's economic, security and climate goals will be more energy efficiency, reinforcement of the power grid, regionally integrated market operations, energy market reform, smart grids and a commitment to phase out high-assets on a fixed timetable.

"Whichever direction you want to go, you probably need to start now," said Tom Brookes, head of the Energy Strategy Centre at the ECF. "Delays only make things much more expensive," he added.

WWF, the global conservation organisation, urged the EU to get to work on a long-term energy strategy based on 100% renewable power, which it says has proven to be as reliable as Europe's current power system.

"This will be good for the climate, phase out risks of nuclear power and fuel import dependency, guarantee power supply and would provide the most cost-effective and acceptable sustainable energy pathway for Europe," said Stephan Singer, director of global energy policy at WWF.

  • 27 Sept. 2001: Renewable electricity directive lays down framework for grid integration of renewables.
  • 23 Apr. 2009: Updated renewables directive gives priority grid access to renewable electricity (EURACTIV 09/12/08).
  • 17 Nov. 2010: European Commission unveils new energy infrastructure package and calls for €200bn investment in energy grids by 2020.
  • 3 Dec. 2010: Ministers from ten European countries (Belgium, Denmark, France, Germany, Ireland, Luxembourg, the Netherlands, Norway, Sweden and the UK) sign 'Memorandum of Understanding' to develop offshore electricity grid.
  • 18 Jan. 2011: German Economy Minister Rainer Bruederle calls for expansion of electricity grid capable of absorbing more renewables.
  • 31 Jan. 2011: Commission progress report calls for doubling of capital investments to meet 2020 renewable energy target (EURACTIV 31/01/11).
  • 4 Feb. 2011: First-ever Energy Summit in Brussels acknowledges that further green growth will require high-tech smart grid at cost of about €200bn.
  • December 2011: The European Commission presented its 'Energy Roadmap 2050' Communication outlining pathways to a low-carbon economy by 2050.
  • 2020: Target date for EU objective of sourcing 20% of its energy from renewable sources.

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