• Electric thermal storage in isolated wind diesel power systems: use of distributed secondary loads for frequency regulation

      Janssen, Nicholas T.; Wies, Richard W.; Peterson, Rorik A.; Mueller-Stoffels, Marc; Xiang, Yujiang (2017-08)
      Isolated coastal utilities in Arctic villages commonly use a mix of diesel and wind power to provide electrical service to their consumers. It is common for such communities to experience periods of high wind generation for which no immediate demand exists and either waste, curtail, or poorly utilize the surplus. The objective of the present work is to explore (through mathematical and numerical modelling) the technical feasibility of and optimization strategies for distributing this excess wind energy as domestic space heat for use as a cleaner, more economical alternative to fossil fuels. Autonomously controlled Electric Thermal Storage (ETS) devices are considered as a solution to decouple the supply of excess wind power with domestic heat demand without the need for communication infrastructure or a second distribution circuit. First, using numerical heat transfer analysis, it is shown that the performance of an ETS heater core can be generalized and expressed in terms of its physical properties and simple geometric dimensions in such a way as to inform system sizing and economic performance studies for prospective applications. Furthermore, a collection of autonomous ETS units is shown (using a full-scale lab-validated mathematical model) to possess the ability to assume the role of partial and/or sole frequency regulator on a hybrid wind-diesel system. Several design changes are proposed, which render the commercially-available units more amenable to frequency regulation. Ultimately, ETS is shown to be a promising alternative means of utilizing excess renewable energy for domestic space heat while providing additional stability to the electrical grid.