Published on October 14th, 2009 | by Susan Kraemer5
School District Revisits Making Ice at Night to Reduce Energy Use
A Florida school district was way ahead of the clean energy curve in the ’80′s. The Hillsborough School District contracted with the first companies pioneering the use of cheap excess off-peak night time power to freeze water at night which would then provide simple cooling by day for air conditioning. Some of those companies had not yet ironed out the kinks in the brand new technology, and recently the district had to find a replacement for these coolers.
A more timid school district might have run from off-peak energy storage altogether. But not Hillsborough. They are taking what they learned and applying their school of hard knocks expertise in selecting from the many companies that now provide second generation night cooling technology to power air conditioning systems.
What’s changed since the eighties is the addition of more wind power to the grid, and the likelihood of more to come with RPS legislation requiring the purchase of more renewable power in many states.
Typically most wind power comes ongrid at night; much more than can be used.
So, according to Forbes “in some parts of the country wholesale power prices are now dropping to zero or below at certain times of the day. In West Texas electricity prices dropped to zero 11% of the time in the 12 months through May 2009…Three percent of the time in the same period, prices dropped to nothing or below in northern Illinois and New York. Overnight prices are also occasionally hitting zero in Ohio and California.”
The Florida school district selected CALMAC, and had their IceBank energy storage tanks installed in five Hillsborough County Public Schools in time to begin providing air conditioning for this school year. Each night, while rates are low, Trane chillers take power from the Calmac IceBank to make ice at night, and then use the ice to provide natural air conditioning to cool the schools the next day during peak energy cost periods.
The CALMAC system saves the Florida school district $50,000 each year in energy costs while simultaneously reducing carbon dioxide emissions by avoided traditional energy use.
But Florida does not yet get much wind power, and this school district will not (yet) be storing wind power. The states where this kind of night time local distributed storage like the IceBank could make the most difference in reducing greenhouse gases now is where excess night wind is going begging, because it blows most often at night when rates are low, and storage is inadequate. Europe has 15% storage, the US under 5%.
Buildings in Texas, Iowa, Ohio and California could save big time with the this technique. Using distributed energy storage systems like the IceBank to absorb and store cheap or free night time wind is a great way to get carbon emissions way down, very cost effectively.
Image: Flikr user Mindflame