Supporting Wind Development with Hydro Balancing Services

The provision of balancing services to wind power generation is an economic opportunity for many hydro generators, according to a report from the IEA’s Wind Task 24. Europe’s hydro generation has not been developed with balancing services in mind.

Potential hydro storage capacity in Europe is so vast that there are many occasions when hydropower would be able to correct the total system imbalances– not only any imbalances caused by intermittency in wind power, according to Ivan Pineda, a research officer at the European Wind Energy Association

Close to 50% of Europe’s storage capacity is in Norway, which has 84 TWh of hydro reservoirs. But within Norway, there is a lot of debate there on how much capability, rather than capacity, the country could provide to balance a major expansion in wind power, says Pineda. The lakes and rivers perform many functions other than energy generation that must be taken into account.

Most of our hydro facilities are not designed for balancing purposes. That is not a problem today, but it will require consideration as wind power expands. At low wind penetration levels into a grid (1% or so), wind integration impacts and costs are minor, according to the IEA Task 24 report. It becomes more costly and more complex as penetration levels increase towards 20%. Beyond 20% or so, changes in system operational practices, such as the inclusion of advanced wind forecasting models, are likely necessary to optimally integrate wind and hydropower.

Wind to hydro ratio

There is no optimal figure for the ratio of hydro required to support a given capacity of wind power. “That will depend on a number of factors,” says Pineda.

An accurate estimate can only be achieved via a detailed simulation of the power system. The operational flexibility of the complete generation fleet, the system load, the level of forecast errors, the cost of wind energy and its marginal value, are just some of the factors that will determine the balancing services and storage needed.

“At the moment the connections between the Nordics and the centres of consumption in Europe are weak. That has to be improved dramatically to support the increase in the offshore wind capacity in the North Sea,” says Pineda.

Greater interconnection has operational and market advantages. Larger balancing areas allow easier integration of wind. As the area increases, localized peaks in supply have less impact and there are more opportunities for supply to find demand.

Large penetrations of wind power in a hydro-dominated power system will lower the spot price of electricity dramatically, according to the Wind Task 24 report. Wind integration costs and impacts tend to be reduced in market systems, especially those with many market actors and flexible resources. An efficient and liquid electricity market has a positive influence on the economics, frequently dominating all other factors.

Pineda argues that grid constraints are damaging the interests of wind turbine operators: “Zero costs or negative costs for electricity are symptoms of a market that is not working. What we have is a lack of capability to transport electricity from the places where it is produced to the places where there are potential consumers.”

Hydro growing fast

There is an oft-repeated myth that the majority of the world’s hydropower potential has been developed. In fact, hydropower has been growing very rapidly and consistently for the past 40 years. In 1970 there was slightly less than 290,000 MW of hydropower in operation. In 1982 global hydropower capacity exceeded 500,000 MW. In 2010 it exceeded 1 million MW for the first time.

Hydropower is being installed at a faster rate than wind power. Some 200,000 MW of wind power were installed in the 12 years between 1998 and 2010. The same quantity of hydropower was installed in the eight years between 2002 and 2010.

Innovation will be needed to optimise the integration of wind power into the European grid. “ One of the biggest challenges is real-time monitoring and the integration of platforms that allow the short term updating of forecasts,” says Pineda. “That will allow greater communication between TSOs and generation units to allow fast responses. Some TSOs are quite sophisticated in their communication systems and the way that they supply reserves. But the variation in wind is not just in minutes but in hours to days. Those variations will need new systems and new strategies for the optimisation of operations and the correct scheduling.”

“The Germans are the ones who will need most of the imported balanced power from these Nordic countries. There is going to be a great investigation and research not only theoretical studies but demonstration projects. I would expect to see more demo projects from the point of view of Germany and the Nordic countries.”