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Dundalk Institute of TechnologyThermal Energy Storage and the first ever on-campus Wind Turbine in the world work together to reduce energy costs in a historical building

OverviewBuilt in the late 1960’s the PJ Carroll Building, on the Dundalk Institute of Technology (DkIT) campus, in Dundalk, Ireland, originally opened in 1970 serving as a cigarette factory. This historical and architecturally protected factory building is one of the finest examples of Mie-sien architecture in Europe. The factory consists of 191,000 sqft. In 2010, 118,000 sqft. of the facility was refurbished to facilitate a college expansion project. The large factory’s system was replaced by an air conditioning system that was designed to incorporate ice-based ther-mal energy storage in order to make more efficient use of an on-campus wind turbine. It also provided an alternative to natural ventilation, which could not be utilized since the building is a protected structure. The installation of energy storage has helped smooth out the electric-ity grid demand profile by allowing more renewable wind energy to be used on site.

ChallengeDue to increases in student population and energy consumption, DkIT was facing rising utili-ty expenses and quickly approaching its maximum electrical capacity. These factors inspired a plan to incorporate renewable energy into the campus’s power generation. In 2005, DkIT commissioned the first large commercial “urban turbine” in Ireland and the first large com-mercial wind turbine on a college campus in the world. Wind energy would produce zero pol-luting emissions and capitalize on an inexhaustible resource. Ireland is known to have one of the best natural resources available in Europe in terms of wind generation potential1 and is currently producing about 10 percent of its electrical energy needs from wind.2 However, even though wind in Ireland is bountiful, the inconsistent nature of wind resources meant that excess electricity was being wasted when demand was lower than the energy produced.

During times of peak demand the energy generated by the turbine was not sufficient to meet the needs of the college. Alternatively, potential savings existed if the campus could address the underutilized wind turbine power generation at night. DkIT needed a solution that could

store excess energy generated at night and use it to even load factors, reduce utility costs and provide micro-grid stability, while maintaining the historical integrity of the PJ Carroll Building.

SolutionDuring the design process the Building Design Partnership (BDP), an international, in-terdisciplinary practice of architects, designers, engineers and urbanists, recommend-ed the use of CALMAC’s IceBank® energy storage technology in order to smooth the load curve that was fluctuating from the inconsistent addition of electricity from

Project Facts:

Retrofit

191,000 sqft. facility

Historical structure

Received a Royal Institute of British Architects award for architectural

excellence

First large commercial

“urban turbine”

Energy generatedby wind turbine

stored in the form of ice Photo credit: BDP & Ros Kavanagh

the wind turbine. The thermal energy storage tanks provided a way for the campus to capture the excess energy from the renewable energy resource that, up until that point, had been sold to the grid due to a lack of demand. With the energy storage and chiller cooling units installed in an underground room adjacent to the building, the architectural integrity of the building remains intact.

Nighttime wind energy that is created by the campus turbine gets stored in the thermal energy tanks in the form of ice. Full charge of the energy storage, while not necessary to cool the building, takes four hours. If the campus electrical demand increases to the point where there is insufficient wind energy, the building management system enables con-trol routines that allow the heating and cooling temperature set points in rooms to decrease or increase. This allows the college to consume less energy and avoid a utility fine.

“The installation went without any problems. The start up and testing was also quite smooth,” said Christian Maas, Building Services Technical Officer at DkIT. “BDP’s recommendation to take advantage of capturing excess wind energy by using CALMAC’s IceBank® tanks has really helped to maximize the use of renewable energy on campus.”

According to Edel Donnelly, Building Services Engineer at BDP, “this installation provides the perfect example of how buildings can be used to even the peaks and troughs cre-ated on the national grid by the addition of wind resources.”

ResultsThe wind turbine generated 30 percent of the campus electrical energy requirements, which included 16 percent of the Carroll building’s load including the air-conditioning system. While the amount of wind energy generated is sub-stantial, due to its intermittent nature, it is not always available to match the peak grid loads. Add the fact that the air conditioning system was calculated to represent 45 percent of the anticipated electrical loading in the Carrol building and you have a real challenge with how best to manage the fluctuating renewable energy supply so that occupants are kept cool and comfortable at all times. The incorporation of thermal energy tanks solved the problem of meeting peak grid loads consistently by storing the wind energy. With energy storage and wind energy, DkIT was able to lower the campus’ dependence on traditional energy resources such as hydrocarbons. Considering that coal accounted for 45 percent of total energy-related CO2 emissions worldwide in 20113, lowering use of fossil fuels is an important component of any energy management strategy.

In addition to lowering the environmental impact, thermal energy storage lowered energy costs. From August 26, 2011 to May 14, 2012, DkIT was able to save nearly $8,000 over using a non-energy storage system.4 Throughout 2012, the wind turbine was able to produce 1,440 MWh, of which 1,141 MWh were consumed by the university and 299 MWh were exported.

Energy modeling calculations based on monthly figures have revealed that the wind turbine in combination with the IceBank energy storage tanks could potentially provide the chiller with 96 percent of its electrical load for the entire structure.4 With 64,000 sqft. still unoccupied, the use of energy storage will increase over the next couple of years as more of the facility is renovated and utilized on a daily basis.

“Looking toward the future, with the advent of smart metering and increase in number of rate structures used by utility companies, reducing peak electrical demand will become more incentivized, especially for larger customers,” said Edel. “This will only increase the benefits of utilizing energy storage such as CALMAC’s ice storage tanks.”

1 Troen, and Peterson. European Wind Atlas. 19892 Wind in Power 2010 European Statistics. Rep. The European Wind Energy Association, Feb. 2011. Web3 “Global Carbon-dioxide Emissions Increase by 1.0 Gt in 2011 to Record High.” Iea.org. International Energy Agency, 24 May 2012. Web. 15 Mar. 2013.4 Donnelly, Edel (2012) “Comparison of Ice-Bank Actual Results Against Simulated Predicted Results in Carroll Refurbishment Project DKIT,” Journal of Sus-tainable Engineering Design: Vol. 1: Iss. 2, Article 3.