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On October 29th starting at 14:00 doctoral student Heiki Lill​ will be defending his thesis „Novel application principles for energy storage technologies in nearly zero energy buildings." 

In this thesis the renewable energy storage options in residential buildings are under investigation. This is to store cheap electricity due to the temporary overproduction of large wind farms and also on-site solar and wind farms.

In an electric system, there should be a balance at all times between energy production and consumption: as much as is produced should also be consumed. Deviating significantly from this balance can damage electrical equipment or cause serious network failures and even blackouts. Unfortunately, both solar and wind energy generation possibilities are associated with (rapid) changes in production.

The simplest examples are wind gusts for wind turbines and intermittent cloud cover for solar panels where the electric output power changes in seconds. In order to smooth out the rapid changes in electricity production, the work proposes the possibility to add ultracapacitors to the battery bank for temporary energy storage, which would act as a buffer and are able to temporarily store the produced electricity. So far, the sale of green energy to the electricity grid has been supported at the state level.

However, this paper examines the next step in how to support the storage capacity of the produced energy in order to increase self-consumption. To this, a state subsidy measure for battery banks is proposed. Due to short-term overproduction of electricity, there are more and more situations where electricity is sold at zero or even negative prices on the power exchange.

The reason is simple - it is more practical for producers to temporarily pay to consumers for electricity consumption than to stop production for a while. This work also proposes a method for storing energy in heat carriers under favorable conditions for the consumer in order to ensure a balance between the production and consumption of the electricity network.

Supervisors are researcher Alo Allik and prof. Andres Annuk. Opponents are prof. Ilhami Colak (Nisantasi University, Turkey) and Arvi Hamburg, PhD (Tallinn University of Technology, Estonia). 

Abstract is available in Library of Estonian University of Life Sciences DSpace archive.