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Tag Archives: grid links

Balancing variable renewables- capacity markets, smart grids or super grids?

By Dave Elliott

The previous few posts have looked at the state of play with renewables in some key countries. In many cases an urgent issue is grid integration and balancing. The variable outputs from wind and PV solar outputs are balanced on some grid systems by using existing fossil-fueled plants, but the later are having a hard time competing, now that some of their peak market has been taken over by low marginal cost (zero fuel cost) wind and PV. To ensure that there is enough capacity still available capacity markets have been proposed, offering extra payments. Some critics don’t like the sound of that- it’s yet another subsidy, in effect for fossil fuel. However, the proposed UK version includes payment for energy storage and demand management options, as well as for gas-fired back up plants, and longer term, fossil gas might be replaced by green gas in the latter. There again there are other balancing options- supergrid links for example, which would open up a new multi-national balancing market.  Which option is best? (more…)

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Wiill the lights stay on?

by Dave Elliott

There has been a long and sometimes heated debate over UK grid security issues, with some claiming that the spread of wind power and PV will undermine it.  Ofgem’s 2013 Electricity Capacity Assessment says ‘Wind generation, onshore and offshore, is expected to grow rapidly in the period of analysis and especially after 2015/16, rising from around 9GW of installed capacity now to more than 20GW by 2018/19. Given the variability of wind speeds, we estimate that only 17% of this capacity can be counted as firm (i.e. always available) for security of supply purposes by 2018/19.’


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US green energy: store, curtail – or export?

by Dave Elliott

The US is pressing ahead with renewables, with around 60GW of wind and 10GW of PV solar already in place.  But that means some system operation issues are coming to the fore.  Since these sources vary, as does demand, when there is surplus output from wind of PV, should it be stored or just dumped?


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Offshore wind grids: Share or compete?

Offshore wind is the big new thing, with the UK doing quite well – taking the lead from Denmark, with around 600 MW now installed and more planned. However there may be battles over how these projects, installed by rival companies, are linked up to land via power transmission links.

Most of the project are now being sited several miles off the coast, linked to land via sea-bed marine cables. There are various ways in which these could be arranged. So far however it could be a case of each offshore project having their own parallel (and very expensive) links back to shore. In some cases that seems likely to involve duplication of effort, with links to rival projects running close to each other, in parallel. It would arguably be more rational and cheaper overall to have a network of offshore links, with possibly a single link back to shore for each region, offering a common service for each project to use. That is even more the case as we go further out to sea, and would be vital if we also build links across the North Sea to the continent- as part of the EU supergrid concept.

In its report last year on Renewables, the Innovation, Universities, Science and Skills Select Committee said that they were: ‘concerned that the proposed offshore transmission arrangements are not appropriate for the UK’s target of 33GW of offshore wind by 2020. We urge the Government to reconsider the development of an offshore grid.’

Imera, who have proposed a Europa Grid linking up North Sea wind to the UK and the continent, made a similar point- there were ‘unused cable capacity in traditional radial connections’, whereas a grid network would be better especially since it could also be used to import/export power.

However, not everyone is enthusiastic about a supergrid network. In a submission in March 2009 (FBEN 29) to the new Energy and Climate Change Select Committee, the German owed utility E.ON commented: ‘A super grid connecting offshore wind farms to adjacent countries is an exciting proposal, but it is unclear whether this is the most cost effective route for connecting new offshore wind. Timely delivery of the supergrid will be an issue. For example, round three offshore windfarms should not be delayed because the connection of a zone is dependent upon a wider interconnection project’.

Ofgem, the energy regulator, has also noted that the advantages with the parallel ‘point to point’ radial approach is that it ‘allows generators to proceed individually and avoid delays due to third parties’, but it has said that it’s also happy with the more integrated network approach. Ofgem nevertheless got a pretty rough ride on this issue at last years BWEA wind conference – it was argued that the proposed grid regime would not encourage joined up networks, and that change was needed to ensure collaborative development and a strategic approach. Do we really need a host of separate lines just to protect competition in the short term?

That was certainly an issue for Green MEP Claude Turmes, who was the European Parliament’s lead negotiator for the Renewable Energy Directive. Speaking at the UK Renewable Energy Associations annual conference earlier this month, he claimed that the competitive tender process favoured by Ofgem was delaying grid connections for offshore wind projects: ‘The UK approach, imposed by Ofgem, for competitive bids for chunks of 40 km cables for offshore, is not very productive, to put it mildly. Much better is the Danish model and the German model, where you have one system operator, the Danish grid company or the regional grid operator in Germany. This company is in charge of delivering the cable to the offshore platform where you then have to plug in your wind turbine. You have to get rid of Ofgem’s over-liberalised idea, by which you can have competition on grid installation.’


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