Ecological design of scour protection for offshore wind power
Typ
Examensarbete för masterexamen
Master's Thesis
Master's Thesis
Program
Industrial ecology (MPTSE), MSc
Publicerad
2024
Författare
Junquera Barbazán, Paulo
Sudjada, Sanna
Modellbyggare
Tidskriftstitel
ISSN
Volymtitel
Utgivare
Sammanfattning
The energy transition plays an important role in the work towards mitigating climate
change and working towards a sustainable development. Wind energy is an
energy source which holds a huge potential when it comes to providing energy from
renewable energy sources. This can be applied to Sweden and neighbouring countries,
as well as globally. There are two types of wind energy, onshore and offshore.
On shore is based on land, while offshore is based in ocean areas. This report deals
with offshore wind power.
Offshore wind turbines are installed in sea areas, and the foundations by currents
standards are attached to the seabed. An important question to take into account
when installing a new offshore wind farm is how the local marine wildlife might be
affected. The currents cause the particles and sediment around the foundation to
move, and these movements can create a hole-like structure in the sea bed against
the foundation. This phenomenon of the sea bed close to the turbine moving, is
called scouring. In order to prevent scouring, wind turbine foundations shall be installed
together with a feasible scour protection. The foundation of the wind turbine
as well as the scour protection has the ability to work as an artificial reef for the
fish living in the area.
Svea Vind Offshore AB is currently developing offshore wind farms in the Baltic Sea,
with the aim of contributing to sustainable development in as many parts of their
projects as possible. At the request of Svea Vind offshore, the aim of this master’s
thesis is to investigate how local marine wildlife interact with different designs of
scour protections, with the purpose of finding the alternative that has the highest
positive effect on local marine wildlife. The operation of wind turbines also emits
low frequency underwater noise, which is taken into account in the study.
The study included three different experiments. The first one tested fish behaviour
in an environment with noise and scour protection, in comparison to a quieter environment
without scour protection. This experiment included testing three different
designs of scour protections; one made out of small to medium-sized rocks, one made
with concrete bricks, and one made with geotextile sand containers. Atlantic cod,
shorthorn sculpin and black goby were selected as fish species for the experiments.
The second experiment involved testing the scour protections against each other,
without adding any turbine noise, and observing which one was the one preferred
by Atlantic cod and shorthorn sculpin. The third experiment tested if the scour
protection that was shown to be most preferred by the fish, was efficient in reducing
scouring from currents. This was carried out by the use of a hydraulic flume machine that generated artificial currents.
Based on the results, the rocks scour protection may offer the most preferable environment
for the Atlantic cod and shorthorn sculpin. This could be due to the fact
that the scour protection resembles their natural habitat and provides shelter. The
black goby did not show any clear preference for any of the three scour protections,
which can be due to its natural hiding behaviour.
The comparison experiment of the scour protections did not demonstrate a clear
preference from any species for one particular scour protection design, which may
be explained by the low number of replicates for this part of the study. Moreover,
the experiment with currents successfully highlighted the importance of scour protections
in the offshore wind power farms, since they effectively prevented the wind
turbine foundation against scouring. In summary, the results of the conducted experiments
indicate the potential benefits of rocks scour protection.
Beskrivning
Ämne/nyckelord
offshore wind power , wind turbine , wind farm , underwater noise , marine wildlife , currents , scouring , scour protection , behaviour study