STORING WIND ENERGYIreland leading the way in stable renewable power production?

A radical new type of energy storage technology will shortly be providing customers in Ireland with a stable, regular power source, proving that energy storage has come of age and is now a commercial reality for mainstream windfarms. David Hopkins, Carbon International reports.

Tapbury Management of County Donegal, Ireland has agreed to buy a 12MWh energy storage system from

Canada’s VRB Power Systems, at a cost of $6.3m. Tapbury manages the Sorne Hill windfarm, a recently-commissioned 32MW windfarm in Inishowen, County Donegal.

The storage system will be coupled to the next phase of the Sorne project, due for completion next autumn, when an addi-tional 6.9MW of wind power capacity will be brought on-line. The VRB system will be able to supply 12 MW hours of power, or 1.5MW over eight hours, enough to meet all the electricity requirements of up to 400 homes. Should the energy stor-age system work as expected Tapbury has already announced that it may expand the power storage elements of the system to cover the existing 32MW of wind power at Sorne, which would equate to approxi-mately 50MWh of additional energy stor-age. In short, the VRB system is more than a pilot project; it has the potential to provide very significant amounts of power to a large number of homes and businesses and, in so doing, further demonstrate that renewable energy really can provide the same kind of stability as coal, oil or gas-generated power.

In the words of Tim Hennessy, VRB’s CEO and Chairman: “The negotiation of this sale has been ground-breaking from the point of view that this will be one of the largest flow batteries to be coupled to a wind farm and it will be the first large-scale system of this type to be installed in Europe. The project will provide high-level visibility

and credibility for our technology for wind applications in what is a fully commercial project”. Once expanded, Sorne, at 38MW, will become one of the largest windfarms in Ireland. With the energy storage system (VRB-ESS™), Sorne will be uniquely able to provide steady, unbroken power whether or not the wind is blowing. Indeed, John Ward, Director and shareholder in Tapbury and Sorne Wind Energy Limited, believes that VRB’s technology could revolutionise Ireland’s power supply. “This purchase is a significant milestone in the development of a real and credible alternative to fossil generation in Ireland and Europe,” Ward said. “With the VRB system, we will be able to significantly expand and develop the

substantial wind energy resources which the country has. In terms of our own portfolio of wind projects, we would have some 70-80MW of wind projects immediately ena-bled by this technology”.

This type of power storage could not only lead to a marked reduction in dependency on fossil fuels and help cut harmful emis-sions by allowing far greater amounts of wind to be used on small and large-scale power networks, it would also provides grid management back-up and boost security of supply. Because of this range of advantages, the technology is already storing energy from Australia and Japan to the US, and systems will shortly be installed in Germany and Denmark. However, it is the installation

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The storage system will be coupled to the next phase of the Sorne project, due for completion next autumn

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in Ireland that is the largest to date. “This is a very important sale for the Company”, said Hennessy, “it is the largest sale we have made and it provides validation of the potential for our storage systems to be coupled to wind farms in the large, growing wind markets in Ireland, Europe and North America as well as a number of other countries worldwide. The VRB technology is the most advanced wind coupled storage system in the world with a very large system installed in Japan and a smaller one installed in Australia. The repeated deep cycling in wind applications makes it virtually impossible for conven-tional batteries or even advanced batteries to compete with the VRB-ESS”.

Renewable storage The VRB technology can store power when the wind is blowing and release it again when it drops, as well as being able to discharge continuous power while simul-taneously charging. Crucially, time does not materially impact its performance, so power stored during a windy day can be released an hour later or three weeks later, when the blades stop turning. Of course, VRB’s technology is not the first to store power; lead-acid batteries are able to do this, as are fuel cells and a range of other relatively new technologies. However, the VRB-ESS’s environmental credentials and its scalability mean it is a fully flexible carbon neutral alternative. It is effectively a larger, environmentally-benign version of a rechargeable battery. Uniquely, VRB uses a solution of vanadium – an abundant natural resource used in steel production – as its key ingredient or electrolyte. Vanadium is a transition metal so can be oxidized and reduced, charged and discharged, time and time again, allowing the renewable storage of renewable energy. This gives the electro-lyte, and therefore the storage capacity of the battery, an almost indefinite life-span.

Unlike lead-acid batteries (and all other technologies except other forms of “flow-batteries”), the amount of energy that can be stored by the VRB-ESS is entirely inde-pendent of its power output rating. In other words this technology is uniquely scalable and could be used for a large wind farm or a single house using a small wind turbine. It can be sized for any amount of power in 5kW or 50kW increments, and can store any

number of determined hours of energy by simply adding additional litres of electrolyte. If you need longer hours of storage, you add more electrolyte, if you need greater output you just add more cell-stacks. It also has far greater efficiency than other storage solu-tions; in the region of 75% depending on its application and use. Unlike lead acid batter-ies, which typically have a 20-25% depth of discharge, 100% of the power stored in the ESS can be used, and it recharges as quickly as it discharges.

Reducing emissionsThe value the VRB-ESS can bring in terms of emissions reductions is already being demonstrated in places such as King Island in the Bass Strait off Southern Australia, where a 200kW (400kW peak) VRB-ESS has been installed alongside a wind farm of 5 turbines to reduce dependence on installed diesel generation. Until the instal-lation of wind turbines and the VRB-ESS, King Island relied solely on costly and pol-luting diesel. Now it benefits from a 40% wind penetration on its grid and will see a significant reduction in diesel costs, and an estimated payback in less then 4 years. It is also estimated that there will be a 46% reduction in emissions (through 75,000 kg of unburnt hydrocarbons each year). According to Simon Clarke, Executive Vice

President Corporate Development of VRB Power: “In small islanded communities you can typically show close to a 3-year payback on the costs of integrating wind and a VRB-ESS into the generating system. The payback is based on cutting the diesel bill by about 50% and by reducing maintenance costs. You also typically cut emissions by over 50%. Depending on the exact loca-tion, it is now cheaper to generate through wind with the VRB-ESS, than by adding additional diesel generation or by adding a gas-fired power station, and even adding coal generation in certain areas is now more expensive than wind and a VRB-ESS.”

Ireland is a perfect example of a country which will benefit hugely from the installation of the technology, as Ward explains. “In the case of Ireland, the windiest parts of the coun-try are those which are least well-connected to the national grid. Wind represents a huge opportunity to provide a very cheap source of energy in these locations once the capital costs are paid off and especially if combined with storage technology. For an economy to have that certainty is very “valuable indeed”. According to Clarke, Ireland’s only workable wide-scale renewable resource is wind: “Even with the current levels of approximately 5% of Ireland’s electricity generation coming from wind the need for storage to stablilise the wind output is being recognized.” So, too are

External view of the storage unit

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the financial benefits of storing night-time energy for sale during the day, Clarke says. “Power pricing depends on the time of day and time of year and exactly where you are, but it is not unusual in Ireland for example, to see a spread of up to Euros 90 per MWh between peak and off-peak pricing, and in the winter it can be even higher. At this kind of spread and on this value stream alone, paybacks in 5 years are achievable. When other benefits are factored in the business case becomes stronger still.”

VRB is so convinced of the potential for its technology in Ireland that it is consider-ing moving some of its activities there. “In view of the significant potential market for storage in Ireland, its ideal location and the attractive capital and other incentives which would be available to us, we are investigating the possibility of establishing a manufacturing facility in Ireland along with a support centre for our European efforts”, Hennessy explained.

Mainland storageEven well-connected countries, like Denmark, have recognized the potential of energy storage systems. Approximately 20% of Danish electricity consumption current-ly comes from wind-generated power and although this is the highest percentage of any country in the world, the government has stated that it wishes this figure to rise to 35%. In June, VRB Power announced it had sold a 120kWh energy storage system for use on the Danish grid. The VRB-ESS has been sold to Riso National Laboratory, as part of a project supported by Energinet.dk, the Danish Transmission System Operator. The VRB-ESS will be evaluated by Riso and its partners with a view to using it in a number of wind power applications, both on and off the grid, and to help the government towards reaching its ambitious targets.

Henrik Binder, Senior Scientist and project manager of Riso commented; “We see the VRB-ESS as one of the technolo-gies that has a potential to be the ‘glue that binds together a power system with a high penetration of wind energy and distributed generation.’ We are looking forward to testing a unit in our SYSLAB – a distributed energy system facility – and characterizing the unit for use in a Danish

context”. Hennessy believes that the “suc-cessful demonstration of the VRB-ESS will help show how storage will alleviate issues of intermittency and curtailment which arise when there is a high penetration of wind generation.” He adds that “the abil-ity of our systems to store electricity at all times, whether peak or off-peak, and to release this electricity when needed most, also enables full value to be realized for all wind generated electricity”.

Indeed, Clarke believes that with the technology, a significant portion of the power on Europe’s large grids could come from renewable sources. “Storage would certainly make this viable in certain areas”, says Clarke. “It depends on the country and the renewable resources. Most countries are initially talking about a 20% penetration rate by 2020 with others such as Denmark and Sweden aiming higher still”.

Attitude shift requiredGiven the benefits that the technology can bring, it is perhaps puzzling why more

grid operators, utilities and wind genera-tors are not using it. Ward believes he has the answer. “We’re talking about a para-digm shift. Until now the networks have believed that energy couldn’t be stored, but they’re wrong”. Clarke agrees. “One of the barriers we come up against is a lack of understanding that full acceptance of storage is needed.

In Europe this is becoming accepted in certain territories but we have yet to find full technical acceptance of the VRB-ESS. As we introduce more systems in the field in high profile areas, we will achieve this acceptance and we hope that, as we deliver on sales, we will be able to demonstrate that a small company in Vancouver really can execute and deliver these large sys-tems.” The Tapbury windfarm is working proof of exactly this.

And with the benefits it will bring it surely cannot be long before approaches to wind generation and storage such as those of Tapbury, inform our attitudes and activities worldwide.

Child’s play? Even well-connected countries, like Denmark, have recognized the potential of energy storage systems

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