The European Union wants a secure and low-carbon supply of energy. Renewables and efficiency measures need to be a key element, and that will require a flexible and accommodating grid network. But will the transmission system be able and willing to remodel itself, or will historic conservatism and vested interest dictate what new capacity gets built, asks Jackie Jones?An old English joke tells of a motorist, who stops at a fork in a small country lane to ask a local fellow for directions to a village he is trying to get to. The chap thinks for a while, scratches his head, and finally says, ‘Well – I wouldn’t start from here’.
If you were designing an electricity transmission system for Europe, one to meet the region’s needs to the end of this century, would you choose to ‘start from here’? Probably not. Consider the ‘destination’ – an electricity transmission system to support a new electricity generation profile that allows Europe to cut its greenhouse gas emissions dramatically, ensure secure supply by reducing dependency on fuel imports, and allow a competitive system to work freely within liberalized European markets – these are the cornerstones of Europe’s ‘Lisbon Agenda’ that drives current policy.
Consider where we are – with a transmission system (originally) built a hundred years ago to serve a system based on large coal-fired generators, and for decades owned by the companies (often later nationalized) generating and selling power to their customers. This established a convention – a mindset – that ‘other’ generation makes things ‘difficult’, even in today’s liberalized markets. Add to this a population with the ‘BANANAS’ mentality (build absolutely nothing anywhere near anyone), and the situation starts to look tricky. On the plus side, though, there are transmission service operators (TSOs) who are embracing high proportions of renewables on their grids, the European association of TSOs (ETSO) and G8 countries have programmes concentrating on increasing grid access for renewables, and technological solutions continue to improve.Transmission fit for a new climate
Over the coming 20 years or so, Europe will need to replace, or build, an estimated 760 GW of new power generating capacity, as elderly power plants are retired and the demand for electricity grows. And according to the International Energy Agency, the European Union will invest €100 billion in transmission networks and €340 billion in distribution networks for reinforcement, asset replacements and new connections between 2001 and 2030. Meanwhile, the world faces not only a climate crisis but uncertain markets for fuel supply, and there is likely be fierce competition on world markets for those commodities – especially for gas from the former Soviet Union. And, as EU Energy Commissioner Andris Piebalgs pointed out at a recent conference, Russia’s own internal market is likely to make very strong demands on that natural gas resource. ‘So the best way to respond to the security of supply question is to produce energy at home’ adding that focusing on wind energy ‘is best answer to the challenges we have today.’
And not just wind – though it is the clear leader amongst new renewables in terms of volume, and (other than large hydro) is the technology connected directly to the high-voltage transmission network. Other renewables are equally important as part of the future energy mix, yet are more likely (except perhaps for large biomass generation) to be ‘distributed’ generation, i.e. connected to the low-voltage distribution grids. These sources are the solar PV roofs, biomass CHP, on-farm biogas, and so on. However, due to its advanced state, most of the discussion here will be about wind power.
In recent years investment in the European transmission system has been limited, with renewables being forced to fit with the system, instead of the system adapting to the new energy source
At present, some 45 GW of wind generating capacity is installed in Europe. If the European Wind Energy Association (EWEA)’s targets are met (which they always have been in the past), there will be 80 GW by 2010. By 2020, EWEA expects 180 GW of wind capacity to be installed across Europe – this would give the continent a penetration (a percentage in the mid teens) equal to that of Germany today. By 2030 the expectation is for no less than 300 GW, equal to Denmark’s current penetration of wind power (20%-25%).
The challenge is to reduce emissions of carbon dioxide. As last autumn’s Stern report pointed out, current and future investments should be made with this in mind – not locking economies into technologies that continue high levels of CO2 production. Speaking at a press conference, ETSO’s Daniel Dobbeni said ‘We are within a change of paradigm – we are contemplating a major shift from a way of living based on cheap energy, and in this context wind power has to become a key element of any European energy policy.’Is there a technical problem?
‘Yes!’, say some. ‘Wind is not reliable, the output keeps varying – it’s too difficult and expensive for us’.
Yet, given the experiences in Denmark, Germany and Spain, it is generally considered that wind energy can meet up to 20% of electricity demand on a large electricity network without posing any serious technical or practical problems, explains EWEA’s report on grid integration.
As for variability and reliability, proponents of wind and other renewables have a range of convincing arguments.
The electricity generation, transmission and distribution systems are complex and extremely impressive, dealing with a real-time process. The entire system is set up to cope with strong fluctuations in load, in order to meet the varying power demands that arise from the patterns of human activity and industry. To an extent, demand is predictable from experience (what happened last time the temperature fell, or rose; what happened last week, or this time last year, or at half-time in the last World Cup Final) so the industry is constantly anticipating shortfalls and surpluses, bringing in or switching off various generators, and – in our liberalized market – trading in advance with partners within the same trading pools. This industry knows variability inside-out.
Second, the output from wind generators can be predicted increasingly accurately, and R&D work is ongoing in this field. The level of accuracy depends quite considerably on how far in advance the forecast is made – for the forecast depends on the available meteorological data.
Wind poses challenges to grid operators, but shorter forecast periods and liberalized markets can help repower
Thirty-six hours ahead, accuracy of a forecast error for a single wind farm is as great as 10%-20% (i.e. the forecast will be 80%-90% accurate). The shorter the lead time, the more accurate the forecast can be. There are considerable advantages if several wind farms are ‘bundled’ together for forecasting purposes, as this helps smooth out some of the meteorological risk. Thus if all the wind farms in an entire area are combined, the error drops below 10% when forecasting on a 36-hour horizon. And working just a few hours ahead reduces the forecast error much further. Thus transmission service operators (TSOs) can benefit from accuracy rates that are well over 90% – at least as accurate as their predictions of demand. (And distributed generation of renewables or high-efficiency CHP can provide stability in the distribution networks, effectively counteracting peaks in power demand.)
In terms of grid stability, wind power has some advantages over conventional generators. As the EWEA report states, wind power does not suddenly trip off the system. Variations in wind energy are smooth, because there are hundreds or thousands of units in operation, rather than a few large power stations. Conversely, when a fossil or nuclear power plant trips off the system unexpectedly, it happens instantly and with capacities of up to a thousand megawatts. (In recent summer heatwaves, such as in 2003 – the first, surely, of many – a number of nuclear and thermal generators across Europe simply had to be shut down when the flow, and temperature, of the rivers meant that they could no longer be cooled.)Smooth operator
In any system, there is a great advantage in obtaining the best possible output forecast. However, while wind generators in feed-in tariff systems (such as Germany) receive a steady price per kilowatt-hour, those working in other markets are subject to the spot-market price. In the UK, suppliers and generators have to provide the TSO with forecasts of planned demand and generation by ‘gate closure time’ – just 1.5 hours ahead of real time, which means that forecasts can have a high degree of accuracy. Yet in many systems, generators can be asked to provide forecasts up to 36 hours ahead. What’s more, generators can be penalized for errors in this relatively long-term forecasting.
According to Poul-Erik Morthorst of Risoe, speaking at the EWEA conference on large-scale integration of wind energy last November, bidding far ahead ‘was designed for conventional power’. He warns that the Nordic 12-36 hour system is now being viewed as the European ideal, and asks ‘Why shouldn’t we shorten the time period for bidding? It would get us closer to real time … So if we need to change it we should act now.’Building a grid for the future
Half a century ago, when history divided Germany into East and West, both sides found themselves with roads and railway lines that no longer had a purpose. They led nowhere that anyone, or any freight, could go. Before ships grew too large to steam up London’s river Thames, you could see signposts for the ‘Danzig’ or ‘Hamburg’ wharves in the centre of London. Before high-speed trains could be introduced across France and Germany, high-quality new tracks had to be laid. Thus routes, and infrastructure, have to suit the needs of the times – and the future. Likewise, once you change electricity generation sites, you need to change transmission.
Although wind is the main renewable energy source in Europe, other such as PV and biogas (pictured) must also be incorporated farmatic
In the early days in Europe, wind turbines were erected in twos and threes by Danish or German farmers, with the electricity being used near to home. Today’s operations are generally larger, but even the relatively small ones require permits and connections in order to feed power into the grid. With the additional trend of building large wind farms in good sites away from centres of population (and particularly with offshore wind farms), the issue of ‘who pays for the grid?’ so that high-voltage transmission lines are in place to connect wind farms becomes even more acute. EWEA’s Christian Kjaer warns ‘if there is no clear policy you could have plants built off the networks.’ (This is, of course, a challenge that Texas faced a few years back, when grid extension to newly-built wind farms the west of the state was not carried out at the expected speed, leaving considerable amounts of wind capacity forced to stand idle – and not repaying investment costs – while grid construction caught up.) But it’s not just about connecting wind farms or new large-scale biomass generators to the grid. As discussed earlier, new forms of generation, such as wind power, along with cross-border trade in liberalized markets, lead to new flow patterns between neighbouring countries. This means that inter-country connections need to be in place in the right strategic positions.
The implication of all this is that Europe needs an energy regulator to ensure that grids are operated in such a way that all forms of generation can be accommodated. ‘These interconnectors are essential – and incentives are needed for these grids to be built’ says Kjaer.Free for all?
As discussed earlier, the transmission grids were originally developed by electricity generating companies, largely based on coal-fired generation or (depending on the geography) hydro-electric power. In many, if not most, European countries the function eventually became nationalized. Nuclear power fitted in well, in being large-scale, and inflexible, reinforcing the expectation that all types of generators act in this way. Though generation from hydro-power can be adjusted relatively rapidly to match demand, it was the advent of natural gas generation that brought real flexibility for the first time and started to help reduce some of the wastage of resources that has always characterized thermal power generation.
Liberalization of the electricity markets – an innovation of Pinochet’s Chile in the 1970s – swept rapidly around the globe and brought a huge number of new challenges, and opportunities. In principle, it is a great enabler of renewable energy, allowing all forms of generation access to the system (rather in the way that all forms of road transport are free to share the highways). Yet what if those grid operators have a business interest in resisting certain types of generation?
In his recent book, Energy Autonomy, German MP Hermann Scheer, ‘father’ of the feed-in tariff, explains why separating (‘unbundling’) ownership of generation and transmission is so important for the establishment of a sustainable energy supply, and how companies that run the grid and also have a free hand over generation can effectively control the way that generation develops (this is the case, for example in France – dominated by EDF – and in Germany, where four main companies are involved.
‘Whoever has the power over the networks also occupies a key position. The layout of the networks influences investment decisions for power plants. Investments by competitors can be prevented or delayed by failing to provide the necessary new network capacity. Where new production sites are required, as in the case of renewable energy, and where exiting network capacity is insufficient, opportunities to obstruct emerge … Whoever has the network can assert that there is a need for large power plants in order to maintain line voltage and frequency.’
Hermann Scheer also writes: ‘In 2003 transmission network operators in Germany made sales of €19 billion. Of these, a mere €1.8 billion were used for investments in the networks; profits came to €6 billion.’ Member of the European Parliament Claude Turmes concurs: ‘The current market is blocking innovation … . investment in the power grid in Germany has dropped over the past 10-15 years’. Meanwhile, he says, some of the large German generator/TSOs ‘have been using their cash to buy up power companies in Eastern Europe.’A push for policy
In January, the European Commission put forward an Energy Package to take Europe to 2020 and beyond, and this is in the process of being approved or rejected by the Council of Ministers (made up of ministers from all the EU member states). Its objective was ensuring that sufficient new power generation capacity is built throughout Europe. Part of its objective is to create, by January 2009, a European internal energy market with open competition and effective regulation in place. ‘A real European grid should work as a one single grid’, said a 10 January press release. A number of technical measures were identified in the Package to achieve these objectives:
- New rules to avoid discrimination, for instance through a clearer separation of energy production from energy distribution. The Commission put forward two unbundling options, expressing a clear preference for ownership unbundling.
- Functioning Europe-wide regulation, not least to facilitate cross-border electricity trade. The Commission said it was necessary to establish a new single body at EU level or, at a minimum, a European network of Independent Regulators.
- With electricity and gas networks are ‘at the heart of a well functioning European market’. The Commission identified measures to speed up investments in key bottlenecks, especially at borders between countries. It identified a number of the most problematic missing links, such as power links between Germany, Poland and Lithuania; offshore wind power connections in northern Europe; electricity connections between Spain and France; gas pipelines from the Caspian to central Europe.
- The Commission wanted to see new legislation to establish minimum market transparency requirements.
- It also called for common minimum, binding network security standards.
However, when the Council of Ministers met to review the proposal for the first time, in February, unbundling was resisted strongly by both France and Germany.
Pro-liberalization, pro-unbundling nations such as the UK supported the Commission proposal, while the EU Competition Commissioner continued to stress that full unbundling was the clearest way to guarantee fair access to energy networks for new competitors. Instead, the Council asked the Commission to ensure ‘effective separation of supply and production activities from network operations’ and ‘guarantee equal and open access to transport infrastructures’ to new energy suppliers, yet without the unbundling proposal in place.A new vision?
‘We need to design networks to meet a vision for the future. We can’t design a network for next 5 years without a longer-term vision’ said Daniel Dobbeni at the EWEA wind integration conference. A few weeks later, German Federal Minister for the Environment Sigmar Gabriel addressed the opening of the European Renewable Energy Policy Conference in January. ‘We need intelligent instruments – e.g. improvement in the efficiency of the grids, and in electricity storage.’ But it is also important to look ahead, he said: ‘Sometimes policy people are lacking in vision. Think of the American vision of putting a man on the moon. We could make it our ‘man on the moon’ project to feed the power of the sun from North Africa into the European grid.’ Another ‘man on the moon’ project (see Alasdair Cameron’s article on offshore wind on page 22) is to build a European supergrid to link offshore generation – originally the brainchild of Airtricity, but now gaining interest and support from the European Commission (see below).
A new vision will also need the public to be on-side. ETSO’s Dobbeni, speaking at the large-scale wind integration event in November, pointed this out: ‘The general public needs to be educated about the need for grid investment so they will give it their support’ – not only financial support, said Dobbeni, but also ‘an appreciation of why new lines may need to go through their backyards’.Can technology offer more?
Research and development, both within the transmission sector and wind turbine design are constantly refining solutions that can help smooth the pathway for wind power on the grid. One example is the low-voltage ride-through capacity developed in the past few years, which enables wind turbines to remain connected to the grid during periods of low voltage caused by system disturbances. Faults on the grid produce voltage dips that otherwise cause wind turbines – normally programmed to drop out at 70% voltage – to trip off the grid, actually making the situation more difficult. With low-voltage ride-through, the wind turbines actually help add stability to the grid.
Another type of development being looked at (E.ON Netz is doing work on this in Germany) is the ability to increase the capacity of existing transmission lines via conductor temperature monitoring.
Finally, some are saying that the future for long-distance transmission, in particular, is not via AC lines but high-voltage DC lines (HVDC) that have no need to maintain reactive power to keep working, and in principle result in lower transmission losses.Finding the way
Like that man trying to navigate his way through the countryside, the European policy and power sectors have some tough wayfinding ahead of them if a sensible destination is to be reached. There is a firm commitment from many quarters to finding the solutions that are needed to accommodate substantial amounts of wind and other renewables on Europe’s grids – yet nonetheless, the relentless message comes from other quarters that only coal or nuclear can be relied on to meet Europe’s future needs.
However, to quote ETSO’s Pierre Bornard: ‘We need the wind industry to supply Europe – that’s clear now’.
Jackie Jones is the Editor of Renewable Energy World
ETSO is working on a study on large-scale integration of wind, to be launched this year
EWEA’s report on large-scale integration of wind is available through www.ewea.org
Hermann Scheer’s ‘Energy Autonomy’ was published in January by Earthscan, www.earthscan.org