Environmental Engineering Reference
In-Depth Information
Conclusions: Issues and Options
The above is far from a complete survey of the many tidal projects underway, but even
so, it is clear that a lot of innovation is going on. There are powerful economic motivations.
One study suggested that the annual world market for tidal technology might be £155-444bn
(ReFocus 2005).
In terms of actual developments, as has been indicted above, while there is interest in
tidal barrages and lagoons around the world, with some significant projects being likely to
materialise, in recent years tidal current turbines have caught the imagination of many more
engineers, and some large developments seem likely to go ahead.
Although the situation now looks quite positive, it has taken some time to build support
for tidal current work in the UK. For many years tidal power, like wave power, was treated as
a marginal option (Elliott 2007). However, with the issue of climate change being taken more
seriously, it is perhaps not surprising that the UK is now pushing ahead quite strongly on tidal
current turbine power, as well as wave power. The UK is well placed to do so having
extensive marine and offshore engineering expertise to draw on, and a major marine energy
resource. A study by
ABPmer for npower Juice suggest that ultimately about 36 gigawatts of
tidal current device capacity might in theory be installed in the UK. It estimated that devices
in under 40m depth might generate around a total of up to 94 TWh per annum- about a
quarter of current UK electricity requirements (ABPmer 2007).
However, it may not be possible to exploit all of that, and certainly it could take time.
The DTI/Carbon Trusts' Renewables Innovation Review in 2004 put the UK's total practical
tidal current resource was put at around 31TWh p.a., about 10% of UK electricity
requirements, while a subsequent study by the Carbon Trust, taking economic and other
constraints into account, put the tidal figure at only 18TWh p.a. (Carbon Trust 2006).
These estimates may be pessimistic. For example it has been claimed that the UK tidal
current resource has been seriously underestimated, by perhaps a factor of 10 or maybe more
(MacKay 2007).
There have been some useful estimates of tidal stream resources in the UK, EU and
around the world (DTI 2004; Hardisty 2007, 2008), but estimates of what might actually be
obtained overall are perhaps inevitably fluid when a technology is at a relatively early stage
of development. It is not clear which systems will be successful in the long run, much less
where they can best be sited and how much of the resource they can harvest, and at what cost.
Whereas enthusiasts obviously hope for rapid progress, it will take time to get the
technology tested and for these issues to be resolved Indeed, as the UK government's
Renewables Advisory Board has noted in a review of wave and tidal current project, progress
on developing reliable commercial-scaled devices has been slower than was hoped, in part
due to the challenging marine environment (RAB 2008). As a result, as yet, no projects had
met the eligibility criteria for support under the Marine Renewables Deployment Fund.
Clearly there is still some way to go technologically, although as RAB point out, a lot of good
experience has been gained.
As indicated above, as in the wind energy field, technologically, the most successful tidal
current devices so far seem to be based on standard horizontal-axis propellers, sometimes
with ducts. However, some novel vertical-axis rotor designs have also emerged, as well as
other novel designs, like the Open Centre turbine and the Pulse Tidal hydroplane system. In
Search WWH ::
Custom Search