Wind power suffers with inconsistency of wind regimes. The association with a powerful storage system could raise the capacity factor of wind turbines. This theme is not new and there are already several articles dealing with this topic. But there is still resistance among technicians in the adoption of this type of association.
Do you have examples of operating systems based on this design?
The incentive programs to wind energy should also not encourage this type of association?
What obstacles must be overcome?
Hi, the Nordic countries are becoming a hydropower energy storage, in particular Norway. During several decades the hydro resources have been used to balance the load and compensate for an intermittent wind power from Denmark. Now, although not formally pumped hydro, it is still a possible way to store and compensate for intermittent renewable sources.
Norway is becoming a renewable energy storage country by connecting via HVDC to continental Europe and providing the required flexibility to a system. Please check NorNed as an example (http://search.abb.com/library/Download.aspx?DocumentID=POW-0048&LanguageCode=en&DocumentPartID=&Action=Launch)
Of course to build pumped hydro is very expensive and that is just one of the reasons for not being a widespread solution. But a scheme like the one used in the Nordic countries might be an alternative as it comes down to efficient use of energy resources.
Regards
Marianne
Another option could be to have an hybrid architecture combining battery on one side and transforming electrical power to gas on the other side through H2 production. This will have the advantage to valorize CO2 and/or to use CO2 from biomass
Mr Plana,
Interesting. And I believe that this setting can be well simulated by software Homer.
Thank you all! I believe an important challenge is the energy storage applications. The h2 solution is good and promising. The disadvantages are the low efficiencies.
Electricity system operators and investors could use pumped hydro energy storage to complement the growing deployment of renewable energy, particularly wind energy. The current grid struggles to push power through when it is being generated in large quantities, and to meet demand when generation is low. Storing energy from wind using pumped hydro means the electricity wouldn’t have to be sold as it is being made, but could be saved for later.
The main drawback in the use of wind energy for the generation of electricity is the intermittent nature of its source. Wind is extremely variable and there is no guarantee that it will blow when it is most needed.
For this reason, large scale integration of wind is a threat to the stability and reliability of utility grids hosting wind energy conversion systems. Moreover, wind power does not help in providing any of the ancillary services such as regulation reserves, voltage control and frequency control and therefore requires a substantial capacity of conventional energy generation that can provide regulation reserve to follow the wind power.
However, in a power system with abundant hydro generation, wind power balancing is achieved quite economically. During the period of high wind generation when load demand can be met by wind generation alone, hydro units can be shut down and water stored in the upper reservoir. This stored water can be used to generate electricity and meet the load demand during the period of low wind generation.
However, there is a limitation due to the stochastic nature of river inflow. The extent to which a hydro plant can effectively balance the wind power variation usually depends on its storage capacity and river inflow. In a power system dominated by thermal power generation, wind integration is a problem due to the ramping rate limitation on the thermal generators.
Even when there is abundant wind power, the thermal generators may at times have to be operated at a non-optimal operating point which makes it uneconomical. Pumped Hydroelectric Energy Storage (PHES) facilities have been considered an attractive alternative for load balancing and energy storage. They can provide ancillary services at high ramp rates, and they can also provide benefits from intraday energy price variation by releasing energy at high demand periods and buying energy at off-peak periods to pump water into the upper reservoir.
Dear colleagues,
when discussing pumped hydro as energy storage means, one might immediately address capacity restrictions. At least in mainland Europe, and in particular in Germany, wind and solar energy are already so popular that the enermous energy fluctuations and grid challenges caused by them cannot be neglected any more.
Pumped hydro does not provide the required amounts of energy storage dimension any more, so that novel approaches such as power-to-gas and fundamental modifications to the grid need definetely to be investigated and implemented.
Perhaps, for this discussion, the link to the paper below in "Energy and Environmental Science", co-authored by myself, could be helpful.
In case you consider the publication interesting, that would be great.
Best Regards
Ulrich
Article Fuel cell electric vehicles and hydrogen infrastructure: Status 2012
Some of the most common questions about wind power revolve around the role of energy storage in integrating wind power with the electric grid. The reality is that, while several small-scale energy storage demonstration projects have been conducted, the U.S. was able to add over 8,500 MW of wind power to the grid in 2008 without adding any commercial-scale energy storage. Similarly, European countries like Denmark, Spain, Ireland, and Germany have successfully integrated very large amounts of wind energy without having to install new energy storage resources. In the U.S., numerous peer-reviewed studies have concluded that wind energy can provide 20% or more of our electricity without any need for energy storage.
How is this possible? The secret lies in using the sources of flexibility that are already present on the electric grid. Every day, grid operators constantly accommodate variability in electricity demand and supply by increasing and decreasing the output of flexible generators – power plants like hydroelectric dams or natural gas plants that can rapidly change their level of generation. Thus, the water kept behind a dam or the natural gas held in a pipeline may be thought of as a form of energy storage, with operators using this energy when it is needed and "storing" it when it is not. Grid operators use these same flexible resources to accommodate any variability introduced by wind energy.
A tremendous amount of flexibility is already built into the power system. Demand for electricity can vary by a factor of three or more depending on the time of day and year, which nationwide translates into hundreds of gigawatts [1] of flexibility that are already built into the power system. Because these power plants and other sources of flexibility have already been built, it is almost always much cheaper to use this flexibility than to build new sources of flexibility like energy storage facilities. While continuing advances in energy storage technology can make it more economically competitive as a provider of grid flexibility, it is important to remember that resources like wind energy can already be cost-effectively and reliably integrated with the electric grid without energy storage.
Late last month, the Australian Energy Market Operator released a report investigating how wind can better be integrated into the power grid. AEMO reports that as more wind turbines are deployed over the next seven years, constraints on the way our electricity grid works – including bottlenecks in the system – mean there may be limits on how much wind-generated electricity we can use.
AEMO has not yet investigated what long-term solutions exist to avoid curtailing wind. But a joint study by the engineering and consulting company Arup and the University of Melbourne Energy Institute is looking at one possible solution.
Electricity system operators and investors could use pumped hydro energy storage to complement the growing deployment of renewable energy. The current grid struggles to push power through when it is being generated in large quantities, and to meet demand when generation is low. Storing energy from wind using pumped hydro means the electricity wouldn’t have to be sold as it is being made, but could be saved for later.
A pumped hydro facility consists of two water reservoirs at different elevations. To store energy, water is pumped from the lower reservoir to the higher one. To generate electricity, water is returned to the lower reservoir through a turbine. This gigantic battery can be used to overcome the wind-related grid constraints AEMO identified.
In our research we have found that, for Australia, the best technology may be pumping seawater up to coastal cliff tops.
Pumped hydro is by far the most significant form of large-scale energy storage used globally. It makes up 99 per cent of all large-scale energy storage.
Unlike conventional river or stream-fed hydroelectricity generation, it does not require a continuous supply of water. This makes pumped hydro less sensitive to drought cycles (although allowances must be made for losing water to evaporation).
Just a wise-guy remark on definitions:
I think you mean "capacity credit" rather than capacity factor.
Capacity factor is the ratio of the net actual annually generated electric energy,, to the energy that could have been generated if the power plant had run at continuous full-power.
Because of the losses of the storage process, storage actually decreases the capacity factor.
Capacity credit is the amount of conventional baseload power that can be left out due to the presence of the renewable power plant. This quantity can indeed be increased using storage. However, emulating a baseload power plant will lead to an inefficient use of resources. For example: if a large supply of renewable power coincides with a large demand it is most efficient to use the supply as it is produced. When the storage is used to emulate baseload power, any renewable power production that is more than the average would be stored irrespective of demand, leading to unnecessary storage losses.
For the rest I agree with Mehdi Hedayatpoor .
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