Master's Thesis Miranda Thiele

 

Assessment of cogeneration systems and heat pumps in energy systems with a high share of renewable energies

Buildings should contribute to the fulfillment of the climate targets by minimizing energy consumption
and environmental impact. A support of the electrical grid by energy management of buildings
is desirable due to variations caused by the energy transition. It can be achieved by cogeneration
systems (CHP) and heat pumps. A meaningful assessment of these technologies is therefore of great
importance.
In this paper, the pros and cons of current and new assessment methods are examined, focussing
on these two heating systems. Additionally, the extension of overall assessment procedures with
the evaluation of grid support by buildings is investigated. Current assessment methods which are
analyzed here include the determination of the annual primary energy demand and greenhouse gas
emissions as well as other methods to account for coproducts of CHP plants. As a new evaluation
procedure, the time-dependent determination of energy factors and the calculation of a key figure
called “Netzdienlichkeitskennzahl R“ are presented.
Linking an assessment of greenhouse gas emissions with the time-dependent calculation of emission
factors can improve the much-criticized current valuation method. Thereby, the actual energy
consumption, and not the estimate of the need, have to be taken into account. In addition, a combined
assessment of the coproducts of CHP plants avoids allocation and its drawbacks. As a new
evaluation criterion, the local network support must be considered. This can be done either by assessing
the readiness or actual activities.