STORM - Specialized Thimbles for Offshore Renewable Marine energy applications

In the UK it has been estimated that there will be an increase in energy demand of 66% by 2050 that could create a large
energy gap. The World Energy Council has estimated that approximately 2 terawatts (2 million megawatts), about double
current world electricity production, could be produced from the oceans with wave, tidal and offshore floating wind arrays
supplying a significant amount (up to 20%) of the UK's future energy needs. However, a critical component in these devices
is the mooring system due to the extreme environments in which they must operate. In the past 10 years there has been
considerable amount of research focused on ropes which has resulted in lighter and stronger products. This now means
that the major weakness in these mooring lines lies at the in-line and end connectors. This weakness currently presents a
major barrier for those wishing to develop the aforementioned energy technologies.
Typically ropes are spliced and metal connectors inserted to prevent wear. However, at these critical areas chaffing of the
rope on the insert can occur, resulting in its premature failure. To assemble the connector within the eye of the ropes the
connector must be split and reassembled onsite. There is a significant commercial need to develop connectors which are
faster, lighter and easier to assemble in order to increase reliability, productivity, whilst also reducing maintenance costs
and improving safety of the device.
The objective of this feasibility study is to design a new multi-material hybrid connector in order to enhance the lifespan of
the mooring system. To date a multi-material hybrid solution has not been marketed for this application. The component
must be corrosion resistant, have a higher strength than polymers, have low coefficient of friction, have high wear
resistance and have good fatigue resistance. No one material offers the range of properties that is required by the
component and thus the innovation arises from the design and the use of combining the latest novel state-of-the-art
nylon/Al materials.
TTI will use state of the art modelling to design a connector for ropes with 60-100 Tonne breaking loads. Nylacast have
produced a revolutionary low friction, high wear resistant nylon material called Nylacast CF072. The component will be
specially designed to ensure that the nylon remains under compressive loads. However, as it lacks strength, BCAST will
produce a lightweight, corrosion resistant core using a novel Al/Basalt fibre composite. This Al material exhibits
considerable increased corrosion resistance compared to mild steel. The research will investigate combining the two
dissimilar materials by overcasting and will investigate mechanical interlock and chemical bonding (using selective
coatings) at the interface. If successful, the consortium will look to upscale the product for larger mooring systems. As
wave, tidal and floating wind energy are in their infancy EMEC will conduct an LCOE analysis to fully determine the impact
of the technology in this marine energy sector with an aim to increase its use and future market penetration.

Academic Impact:
This research will have an impact on academics working in; renewable energy, materials science and marine engineering.
The scientific impact is manifested in combining two novel technologies to produce an enhanced composite component.
Knowledge will be gained in understanding how these two materials will interact together and the enhanced properties that
can be attained through their interaction. It embraces interface, composite, metal and polymer science.
Technological Impact:
This component will be designed to be subjected to compressive loads yet still maintain an easy fit assembly. It will
demonstrate increased wear and corrosion resistance whist maintaining strength in the end and in-line connectors in
mooring lines. It will thus improve reliability and durability of the energy device by reducing downtime and increasing
service time. This in turn will increase its productivity helping to reduce the overall cost of the energy produced with an
LCOE goal of £100/MWh by 2020. A recent report by Ernest and Jones has indicated that offshore wind will have to reduce
its capital and operation costs by 26% by 2023 to be competitive. The technology may also be adopted in the shipping and
oil and gas industries thereby significantly increasing its impact. The understanding of the joining between the dissimilar will
also have a substantial effect on state-of-the-art lean manufacturing processes from automotive to general engineering
applications.
Environmental Impact:
Demand for electricity in the UK in 2014 was on average 34.42GW (peak 52.7GW) or 2249TwH (equivalent to 193.4 million
tonnes of oil per year). At present the increase in energy demand in the UK is expected to reach 66% by 2050 that could
potentially create a substantial energy gap. Fossil fuels still currently produce ~56% of the UK's energy. In 2014 19% of
energy was produced by renewable sources thus exceeding the UK's 2020 target. The Department of Energy and Climate
Change (DECC) estimated that offshore floating wind, wave and a tidal devices could generate 20% of the UK's current
usage with potentially 27GW possible by 2050. 1 GW can power approximate 700,000 homes (the UK has 25 million in
total). This technology will continue to enhance the uptake of renewable energy and contribute to the reduction in UK CO2
emissions which must be reduced 34% by 2020 and 80% by 2050. This will assist the UK in in its transition to a greener
more sustainable economy.
Economic Impact:
The global market for marine energy has been estimated to be worth around £76 billion between now and 2050. The
economic impact of this research will arise from: increased productivity and reliability of the energy device, access to new
deep water sites, the reduction in expensive offshore underwater construction (including its associated infrastructure -
already, offshore foundations account for over 60% of all installation costs), and the reduction and renewal of expensive
mooring lines. The cost of a single mooring line can be up to £400k with the connectors and spools representing
approximately 27% of this cost. In terms of mooring replacements £100k per line typical every 5 years is required with each
energy device typically having 1 to 3 mooring lines i.e. a cost of up to £300k every 5 years per device. Moreover, this will
help secure the UK's energy needs and supply and thus protect the UK's wider economy which requires cheaper energy to
remain globally competitive.
Benefit to Society:
The ultimate benefit to society as a whole will be an improved quality of life arising from a cleaner living environment,
resulting in many health benefits due to the reduction in pollution. The cheaper sustainable energy will also result in cost
savings for users and this in turn will generate employment.