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Center for Nonlinear Studies |
The statement “energy is not storable” is heard in energy conference lectures around the world, even though each person in the audience is sitting in a vast energy storage device. The heat storage in buildings is an enormous untapped resource for providing regulation services. Through appropriate intelligence at an HVAC (Heating, Ventilation, Air Conditioning) load, the power consumption can be varied around its baseline without adversely affecting the indoor climate. This variation is exactly analogous to the charging and discharging of a battery. Such ancillary services from loads will be especially important as the grid is subject to more and more volatility from the introduction of power from renewable energy sources.
This talk describes recent work done at the University of Florida (UF) on obtaining virtual storage from VAV (variable air volume) HVAC systems in commercial buildings. Both simulation studies and experimental verification – conducted at a 40,000 sq. ft. commercial building at the UF campus – will be presented. There are a number of technical challenges in bringing the vision of ‘virtual storage from flexible loads’ to reality. First, the variation in power consumption must be constrained to an appropriate bandwidth, or timescales. Otherwise quality of service, measured by indoor climate, energy consumption, etc. will be adversely affected. Another challenge is estimating the baseline itself. Finally, there are the pesky details of the actual implementation. We will describe our approaches to solving these problems for two distinct time scales: high bandwidth (a few seconds to a few minutes) and medium bandwidth (a few minutes to an hour). What is the slowest time scale at which HVAC can be used to provide virtual storage - without unacceptable changes to quality of service metrics - is still an open question.
Host: Scott Backhaus