Project no. 204
Design and Optimization of Hybrid Solar-Biomass
Systems for Combined Heat and Power Generation
DTU Mechanical Engineering, Technical University of Denmark
Hybridization of biomass and solar is becoming an increasingly interesting technology to
look at when designing a renewable system for power and/or heat generation. This is due to
its potential in providing a dispatchable base-load energy demand. With an increasing
political pressure in many countries to lower their carbon emissions, this technology could
be implemented as part of the energy portfolio. Denmark in particular has set up a goal of
being completely independent from fossil fuels by 2050.
Hybridization of biomass and solar expands the area where it is possible to benefit from
large scale solar plants. This can be seen by the technology allowing a northern European
country such as Denmark, to use this technology for district heating systems. In a country
where 64% of all households are connected to the district heating system this technology
can have a big impact. However, the technology is still being researched and developed,
which makes it a hot topic in the Danish energy debate.
All of the above is what provides the motivation for this project, where the goal is to help
further the development in this field. The benchmark of the project is a district heating plant
in Marstal Denmark. The district heating plant in Marstal was built in stages and might not be
running at optimal conditions. Therefore, it is of interest to determine the optimal size and
type of the different components, the main components of interest being the solar field and
the storage systems. This leads to the following problem statement:
- What is the optimal design and layout of a hybrid solar-biomass system for
combined heat and power generation in Denmark?
To ensure that the problem statement is answered a set of tasks and methods is created.
First a dynamic model of the system is developed and validated in TRNSYS. Next follows an
optimization of the solar fields and storage systems along with an evaluation of which
auxiliary heating components are needed.
Finally, a techno-economic analysis will be carried out, where after it is possible to evaluate
and rate different designs. This will be done on the basis of the capital investment cost and
the internal rate of return.
RESULTS AND CONCLUSION
At this point in time only preliminary optimization results have been found with a validated
model. A methodology to determine the solar field size and the size of the storage systems
in order to meet a given heating demand has been made. Once the techno-economic
analysis has been made, different combinations of district heating plants will be compared