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4
Wave power development and the
utility perspective
4.1
Overview
There are around 50 to 100 wave power concepts actively being developed,
i.e. RD&D being carried out on a daily basis in an associated company. The
majority are however at an early phase (see Ch.4.2) and have so far not
encountered the major economic and technological hurdles. Furthermore
these companies are small with more or
less strained economics, which
makes the day-to-day struggle more important than the longer view. However
understandable this is, it means that that the system perspective is somewhat
neglected and to be blunt some wave power developers have rather vague
insight in large-scale power generation.
Utility scale wave power would mean large farms (100 MW+) in order to be
meaningful and, in all probability, to be economically viable. Thus from a
utility perspective wave power devices need to be able to be installed and
connected to the grid in large numbers, be able to be maintained and have an
acceptable economic performance.
This chapter will look at issues of interest from a utility perspective. The
following section will however briefly discuss the
various development stages
of wave power concept to give a background of the challenges for the wave
power developers.
4.2
Development stages
There are several ways to categorize the development stages of new
technologies e.g. NASA uses a measure called TRL, Technology Readiness
Levels, that consists of nine different development levels with defined
technical milestones. Another measure developed
specifically for the marine
energy sector is the Irish Ocean Energy development and evaluation protocol
with five levels including indicative costs for each step.
The wave energy sector is often compared to the wind energy sector, and
especially the offshore wind energy sector. It is often heard that wave energy,
in terms of technological maturity, is some ten to fifteen years behind the
wind sector. Indeed there are many similarities between offshore wind and
wave energy, but there are also some fundamental differences.
Whilst wind
energy converters have been developed as an onshore technology that has
been applied to the offshore, most wave energy converters are developed for
offshore operations from the start. Being offshore increases the obstacles that
must be overcome (e.g. survivability) and the wind energy sector could prove
the technology onshore before taking the step offshore whereas the wave
energy sector must face all challenges associated
with being at sea with the
first prototypes.
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Furthermore, there is a fundamental difference in how a wind turbine harvests
the energy compared to a wave energy converter that influence the
development process. A wind turbine’s capacity to produce power is very
much determined by the area swept by the turbine. The ability to produce
power for a wave energy converter is strongly connected to the weight of the
device than, for example, the water-plane area. Wind turbines have been able
to grow from rather small devices
rated in the tens of kW, to the multi-MW
machines in a commercial arena. The same site used for a small-scale wind
turbine some 15-20 years ago can today be used for large-scale wind energy
generation. However for wave power the cost of offshore works (e.g. sub sea
cabling or piling) would be prohibitive for small-scale units. Furthermore,
since mass and inertia are such central factors in wave energy there is no
point in deploying and connecting a scaled wave energy converter in EMEC or
WaveHub, the two currently operational marine energy
test centres with sub
sea electrical infrastructure installed, since such a device would be too light
and only produce trivial data. Indeed, there are test zones in Europe for
scaled devices e.g. the Irish test zone in Galway bay, but all these sites lack a
grid connection. To get offshore experience and results wave energy
developers are more or less required to go to full scale.
A simplified description of the development
process for wave energy
converters is given in Figure 4.1, and the different stages are described in
more detail below.
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