Reliability analysis of wave energy converters
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Date
13/04/2022Author
Lopez-Chavez, Ricardo Antonio
Metadata
Abstract
The energy demand worldwide is increasing, and such demand should be
satisfied with renewable resources to diminish the carbon footprint. There are
a few ways to produce clean energy such as wind, solar and marine energy;
however, some technologies are more developed than others and more
expensive than others.
Wave energy is a type of technology that allows the generation of energy from
waves' motion; its theoretical potential is enormous, and it is essential to exploit
that resource to satisfy the increasing global energy demand.
However, wave energy converters (WECs) have not achieved the desired
maturity level commercially and on the design. Its high cost and current stage
of development require significant analysis to improve the design and reduce
costs.
Reliability analysis of WECs is vital to compare different types of converters
and identify the most critical components with the highest failure rate.
Following a WECs classification, generic WECs have been developed,
surrogating failure rates from other industry databases (e.g., oil & gas and wind
industry) and adapting them into the WECs environment. Then, the overall
system failure rate has been calculated.
After all the analysis and comparison between the WECs’ sub-assemblies,
hydraulic PTO has been identified as the type of PTO with the highest failure
rate mainly because it has a higher number of components, while direct drive
is the sub-assembly with the lowest failure rate. Overall, the structure sub-assembly failure rate is significantly lower when the WEC is installed on the
shoreline because materials, such as concrete, are used and are not exposed
to extreme conditions as if it was located offshore. Moreover, those converters
do not require mooring systems and their structure is less complex, decreasing
the overall failure rate.
Later, based on the criticality analysis and failure modes, it was identified that
the hydraulic systems have components with a higher criticality value – if the
component fails, the generation of electricity stops, and urgent maintenance is
required. On the other side, a simpler PTO such as a direct drive has a lower
number of components with high criticality values, suggesting that such PTO
has a lower failure rate and less critical components.