Energy Storage in Ordinary Houses. A Smart Grid Approach

Abstract The last couple of years more and more non-controllable energy sources, e.g. wind turbines, have been connected to the power grid. This has caused an inefficient energy production and a huge variation in the energy prices. In the near future (10 to 15 years) the amount of non-controllable energy sources will double or more. This again will result in a number of problems: Inefficient energy production, problems with controlling the power grid, the wind turbines have to stop when the wind is optima and so on. A way to reduce these problems is to use the possibility to store energy in ordinary houses. Ordinary houses are the main electricity consumer. More than 60% of the total electricity production is consumed in family homes. A way to overcome these problems with non-controllable electricity production is to use residential homes as energy storage. For instance floor heating systems, hot water tanks, refrigerators and freezers are all examples of systems and appliance that can be used for storing energy in an efficient way. Beside of that it is possible to use the washing machine, the dryer and the ventilation in a more flexible manner which will have the same effect than storing energy. This paper analyzes the possibility for using floor heating systems and hot water tanks as energy storage in ordinary family houses. Beside of that the size and the efficiency of this energy storage are analyzed. The main idea are to make the power consumer more flexible, or in other word the consumer have to use the energy when it is available, and by that mean secure a more efficient and green energy production. If houses and private households have to play that role, then it is very important to find a solution that minimizes the impact on the living comfort. The way to do that is to make an automatic and intelligent house control system that maximizes the consumption flexibility based on the energy user's behavior without affection the living comfort. This behavior is of course different from household to household, because of that it is necessary to include an adaptive behavior prediction system. This paper describes a method for making houses more energy flexible based on pre knowledge of the user behavior. The energy flexibility is calculated based on simulation for 200000 typical houses in Denmark. The simulations shows that it is possible based on these 200000 houses, to store enough energy to absorb the variation in the production in Denmark over a time horizon on several hours.