Home
Ocean Power
 
Back
 
Ocean Energy Review 2008


Alt Dot Energy
January 1, 2009


A look at the wave, tidal and ocean current power renewable energy technologies,
the companies and project news during 2008.

While much of the attention on renewable energy in recent years has focused on
solar and wind technologies, awareness has been growing around the enormous
energy generating potential of the Earth’s oceans. The first ocean power system
connected to the grid opened in Orkney, Scotland, in August 2004; it’s a test
system producing 750kW. Orkney will eventually be home to 40 such systems in a
“wave farm,” producing 30MW of power.

WAVE POWER

A 2005 report from the Electric Power Research Institute stated that wave power
properly and effectively harnessed, would likely have minimal environmental
impact, and be much less visible on the landscape, than competing technologies.
At the same time, waves possess the advantage of being more predictable than
either wind or solar, which in principle makes it a more reliable source of
energy. It is also estimated that the theoretical global wave power resource is
between 8,000 and 80,000 TWh/year. A tremendous amount of energy that is several
times greater than the actual global electricity demand.

The rapidly expanding field of wave power is rife with innovation and an
extraordinarily diverse range of approaches. Several technologies have been, and
are being, developed and tested in coastal regions around the world. So far
however, technical challenges involved in engineering a sufficiently
inexpensive, efficient and reliable method of extracting this energy have proven
difficult enough that as yet there is no agreed upon ‘best way’ to do it.

Among the significant difficulties facing engineers of commercially viable wave
power have been durability in storms, and low generating capacity factors
resulting from the difficulties of extracting a steady load from constantly
shifting wave motions. Irregular and alternating wave motions lead to large
variations of the power produced, severely limiting the power output of many
Wave Energy Converters (WEC).

Ocean Harvester

Mikael Sidenmark, founder of Ocean Harvesting Technologies, and the inventor of
the Ocean Harvester (pictured above), has developed a method of generating
electricity from waves that offers compelling and cost-efficient solutions to
these problems.

As Sidenmark explains:

A buoy follows the wave motions at the surface. When the wave rises, a drum
inside the buoy is rotated by a mooring line wound around it, converting
vertical motion into a rotation. This is a very efficient way of extracting
energy from waves that is independent of the wave sizes and has been used in
earlier technologies.

What is unique with the Ocean Harvester is the way a counterweight is used to
achieve a leveled and controlled load on the generator. As a result, excess
energy from larger waves can be accumulated and used to compensate for shortage
from smaller waves. In combination with the flexible mooring, this also composes
a simple and efficient storm protection system.

Together, these characteristics result in an exceptionally high capacity factor.
The system should produce a consistent level of power throughout the wave
motion, over changing wave sizes, and even in storms. Besides generating
efficiently and evenly, the simplicity of its design will allow the Ocean
Harvester to be easily protected in rough conditions, and make its manufacture
impressively cost-efficient.

Ocean Harvesting Technologies is currently planning a two-year scale model
testing period, slated to begin in March 2009 in the coastal Blekinge region of
Sweden, on the Baltic Sea. The company expects the Ocean Harvester to enter the
commercial market in 2013.

Pelamis Wave Energy Converter

The Pelamis Wave Energy Converter is a technology that uses the motion of ocean
surface waves to create electricity. The machine is made up of connected
sections which flex and bend as waves pass; it is this motion which is used to
generate electricity.

Developed by the Scottish company Pelamis Wave Power (formally Ocean Power
Delivery), it was the world’s first commercial scale machine to generate
electricity into the grid from offshore wave energy and the first to be used in
commercial wave farm project. The first full scale prototype was successfully
installed and generated electricity to the UK grid at the European Marine Energy
Centre in Orkney, Scotland in August 2004. The first wave farm, located off the
coast of Portugal, was officially opened in September of 2008.

The Portuguese minister of the economy officially opened the worlds first wave
farm, consisting of three Pelamis wave energy converters, on the 23 September
2008. The farm is located at the Aguçadoura Wave Park near Póvoa de Varzim in
Portugal. It has an installed capacity of 2.25MW, enough to meet the average
electricity demand of more than 1,500 Portuguese homes. A second phase of the
project is now planned to increase the installed capacity from 2.25MW to 21MW
using a further 25 Pelamis machines.

AquaBuOY

In the US, the wave energy company getting the most attention has been Finavera
with it’s AquaBuoy system, which has received preliminary approval to build a
100 MW facility off northern California (and has signed a power purchase
agreement with PG&E for part of this). At hasn’t all been plain sailing for
Finavera however, with a test AquaBuoy device sinking off Oregon late last year.
The Electric Power Research Institute (EPRI) estimated that waves off the
Washington, Oregon and California coasts could produce from 250 to 500
terawatt-hours per year - around 12% of US energy demand. Finavera also has
approval for a project in Washington state, along with others in South Africa
and Canada.

Oceanlinx

Australian company Oceanlinx (previously known as Energetech) has had a 450
kilowatt wave power unit running at Port Kembla in NSW for a number of years,
and plans to connect to the commercial power grid in early 2008. Oceanlinx is
also at the advanced permitting stage for a project in Portland, Victoria which
would deploy eighteen 1.5MW units for a total capacity of 27MW, which the
company claims will be the largest wave energy project in the world.
The company has other projects planned in Rhode Island, Hawaii and Namibia, and
intends to participate in the South West of England Regional Development
Agency’s “Cornwall Wave Hub” in the UK.

Power Purchase Agreement (“PPA”) has been signed with Australian utility
Integral Energy for the supply of electricity from the prototype 450kW unit
currently deployed at Port Kembla (New South Wales, Australia).
Both wave energy devices developed and installed so far by Oceanlinx can be
viewed in high resolution on Google Earth. It is believed that Oceanlinx is the
first wave energy developer to have two different devices in the water
concurrently. Both devices are offshore from Port Kembla. The bottom mounted MK
1 device can be viewed at 34° 27’ 07.6” S, 150° 54’ 06.8” E. The floating MK 2
device is positioned at 34° 28’ 16.7” S, 150° 54’ 56.5” E. Simply type these
coordinates into the Fly To section, in the upper left hand corner of the Google
Earth page.

TIDAL and OCEAN CURRENT POWER

Tidal power stations can take the form of a dam (or barrage) built across a
narrow bay or river mouth. As the tide flows in or out, it creates uneven water
levels on either side of the barrier. The water flows through the barrier,
turning turbines to generate electricity. Underwater turbines can also be used
on their own to harness both tidal power and ocean current power. The turbines
(sometimes called aquanators) are similar to wind turbines. In water moving
between 6 and 9 km per hour, a 15 m diameter water turbine could generate as
much energy as a 60 m diameter wind turbine. Given the smaller amount of
infrastructure required and the larger range of possible sites that this
technology could be deployed to, it seems likely that underwater turbines will
become much more widespread than tidal barrage style generation.
SeaGen

SeaGen, the world’s first commercial scale tidal stream turbine, designed and
developed by British tidal energy company, Marine Current Turbines, has for the
first time generated at its maximum capacity of 1.2MW. This is the highest power
so far produced by a tidal stream system anywhere in the world and exceeds the
previous highest output of 300kW produced in 2004 by Marine Current Turbines’
earlier SeaFlow system, off the north Devon coast.

SeaGen works in principle much like an “underwater windmill”, with the rotors
driven by the power of the tidal currents rather than the wind. It was deployed
in Northern Ireland’s Strangford Lough in May of this year and since then has
undergone commissioning trials. As SeaGen has now reached full power it will
move towards full-operating mode, for periods of up to 22 hours a day, with
regular inspections and performance testing undertaken as part of the project’s
development programme.

The power generated by SeaGen is being purchased by Irish energy company, ESB
Independent, for its customers in Northern Ireland and the Republic of Ireland.
SeaGen has the capacity to generate power to meet the average electricity needs
of around 1000 homes.

Drawing on its experience of Strangford Lough, Marine Current Turbines’ next
project, announced in February 2008, is a joint initiative with nPower
renewables to take forward a 10.5MW project using seven SeaGen turbines off the
coast of Anglesey, north Wales. It is hoped the tidal farm will be commissioned
around 2011/2012.

Using its SeaGen technology, the company is also investigating the potential for
tidal energy schemes in other parts of the UK and Ireland, and in North America.

On the west coast of Canada, Marine Current Turbine and BC Tidal Energy
Corporation plan to install at least three 1.2 MW tidal energy turbines in
Vancouver Island’s Campbell River by 2009. This the first step in a plan to
develop larger tidal farms off British Columbia’s coast, which the company says
have a tidal energy potential of up to 4,000 MW.

Hydro Green Power

The USA’s first commercial hydrokinetic turbine, which harnesses the power from
moving water without the construction of a dam, has splashed into the waters of
the Mississippi River near Hastings, Minnesota.

Although not strictly speaking ocean power technology I thought it was worthy of
inclusion in this review.

The 35-kilowatt turbine is positioned downstream from an existing
hydroelectric-plant dam and — together with another turbine to be installed soon
— will increase the capacity of the plant by more than 5 percent. The numbers
aren’t big, but the rig’s installation could be the start of an important trend
in green energy.

And that could mean more of these “wind turbines for the water” will be
generating clean energy soon.

“We don’t require that massive dam construction, we’re just using the natural
flow of the stream,” said Mark Stover, a vice president at Hydro Green Energy,
the Houston-based company leading the project. “It’s underwater windpower if you
will, but we have 840 or 850 times the energy density of wind.”

Hydrokinetic turbines like those produced by Hydro Green and Verdant capture the
mechanical energy of the water’s flow and turn it into energy, without need for
a dam. The problem for companies like Hydro Green is that their relatively
low-impact turbines are forced into the same regulatory bucket as huge
hydroelectric dams. The regulatory hurdles have made it difficult to actually
get water flowing through projects.

Tidal Power Projects by Country

In the United States, at the southern end of the Bay of Fundy, lies
Passamaquoddy Bay, which has long been a target for a tidal power development -
first initiated in 1935 by the Public Works Administration under the Roosevelt
administration, then halted by Congress a year later. John F Kennedy revived the
550 MW project in 1963, however the plan died with him.

Further south, in the Martha’s Vineyard area, two underwater turbine projects
are trying to get started - one a 300 MW proposal from Oceana Energy Company and
the other from Natural Currents Energy Services. Other projects are being
considered in the Cape Cod and New Bedford areas - part of a “gold rush” for
good tidal power sites (the most desirable ones usually have hourglass figures,
to get maximum force in the incoming tide) which has seen the FERC issue 47
preliminary permits for ocean energy projects (and generated mainstream news
coverage on the NBC network).

New York’s East River is the location of one of the more high profile tidal
power experiments currently underway, with Verdant Power experimenting with
underwater turbines there. The first attempt eventually ended in failure, with
the strong tides breaking the devices.

The Gulf Stream has also caught the eye of hopeful ocean energy companies,
particularly in Florida, with the 30 mile wide current pushing 8.5 billion
gallons of water along per second and prompting some observers to consider the
prospect of “Infinite Underwater Energy“.

Californian utility PG&E is also investigating tapping tidal power in San
Francsico Bay, with some observers talking about a plant of up to 400 MW in size.

In the UK, another bay famous for its tides is the Severn river estuary in
Britain, with a tidal range of 14 metres. Plans for damming the Severn estuary
or Bristol channel have existed since the 19th century (with tidal power
generation being just one proposed application). The UK government recently
proposed a new barrage design, which could produce 5% of the UK’s electricity
requirements, with a peak rate of 8.6 GW. A feasibility study is expected to be
complete by 2010. An alternative proposal, by Tidal Electric, involves a series
of lagoons, the first of which would be built in Swansea Bay. Some observers
have noted underwater turbines may be more appropriate than a barrage.
Pentland Firth in Scotland is another UK location that is considered to have a
large amount of tidal power potential - a DTI study in 1993 indicated that if
all potential sites were developed, the total UK tidal stream resource could be
about 60 TWh. Of this, almost half (28 TWh) could come from the Pentland Firth.
The water depth is 60m or more, making potential energy capture huge but
technically difficult - 63% of the tidal stream resource is estimated to be in
waters deeper than 40m.

Marine Current Turbines launched the world’s first underwater turbine project
off north Devon in 2003. MCT also began installing a 1.2 MW “SeaGen” tidal
current turbine in Northern Ireland’s Strangford Lough in 2007, with the company
planning to scale up to build a 10MW tidal power farm off Anglesey in North
Wales, and to have 500MW of tidal capacity by 2015. Also in Wales, Lunar Energy
and Eon are hoping to build an underwater tidal project off Pembrokeshire.
Another UK tidal power proposal is part of a plan by Metrotidal to build a
tunnel under the Thames, currently under fire from environmental groups. There
is also talk about regions like the Isle Of Wight and the Humber estuary
harnessing tidal power as part of initiatives to become energy self-sufficient
(like other “Transition Towns”).

Norway has also begun investigating the use of tidal power, with an experimental
facility opening in Hammerfest in 2003. The company that developed that
technology, Hammerfest Strøm, is working with Scottish Power to develop a
project near the Orkney Islands (the islands have also been a test site for
another venture by Lunar Energy and Rotech).

In Australia the Kimberly region has long been a target for would be developers
of tidal power projects, due to its enormous potential (a tidal range of 11
metres). Thus far all of the proposed projects have been stymied by the
remoteness of the location from the Western Australian and national electricity
grids and by environmental concerns. A number of possible sites have been
identified, including Secure Bay, Walcott Inlet, George Water and St. George’s Basin.

Some Kimberly tidal power advocates have also tried to base the idea of a
“hydrogen economy” on the resource, though this seems a lot more far-fetched
than a grid link (the grid link could also potentially include large scale CSP
solar in the western australian deserts, which are one of the best solar
resources in the world) .

The Bass Strait area is also considered to have significant potential for tidal
/ ocean current power generation (one estimate claiming there is potential for
3000 MW of generation in the channel between King Island and Cape Otway).

New Zealand is another country with large tidal resources but without any
existing tidal energy generation. According to TVNZ, there are at least 24 wave
and tidal power projects currently under development. Trying to get a handle on
who might be behind these projects isn’t easy - there is an NZ wave and tidal
power association, but it doesn’t list members or projects - according to their
latest newsletter they have 59 members. Crest Energy seems to be the most
prominent local company, with a plan for a 200 MW plant in Kaipara Harbour using
underwater turbines. Other potential locations include Manukau and Hokianga
Harbours, and Tory Strait and French Pass in the Marlborough Sounds. The
harbours produce 5 to 6-knot currents and tidal flows of 100,000 cu m a second
from the flood and ebb tides, with tidal volumes 12 times greater than the flow
in the largest local rivers.

The Phillipines is another potential location for tidal power, with a 2.2GW
tidal fence proposed for the Dalupiri Passage using the Davis turbine, from the
Blue Energy company and an estimated cost of $US 2.8 Billion is unfortunately on
hold due to political instability.

South Korea also has ambitions to generate power from ocean currents, with pilot
underwater turbines being installed at Uldolmok, in the country’s south-west.
Researchers at the Korea Ocean Research and Development Institute (KORDI) chose
the site because it has flows up to 12 knots, believed to be among the fastest
in Asia. The strong currents have resulted in a number of accidents, hampering
progress. KORDI is also trying to improve the efficiency of more conventional
barrage-type tidal power plants. The primary project involves building a power
plant with a capacity of 250 MW at Lake Sihwa, with another plant up to 520 MW
being considered for Garolim Bay.

Taiwan is another Asian nation considering the the possibility of large-scale
ocean current power generation. There have been discussions about using the
strong Kuroshio current off the east coast of Taiwan to generate up to 1.68
trillion kilowatt-hours per year (compared to Taiwan’s current annual demand of
electricity of around 98 billion kilowatt-hours).

New Technology

Probably the most exciting bit of Hydropower news this year was the news of a
new technology that can generate electricity in water flowing at a rate of less
than one knot - about one mile an hour - meaning it could operate on most
waterways and sea beds around the globe.

This new device utilises a novel approach to extract energy from flowing water
currents. It is unlike any other ocean energy or low-head hydropower concept.
VIVACE is based on the extensively studied phenomenon of Vortex Induced
Vibrations (VIV), first observed 500 years ago by Leonardo DaVinci in the form
of “Aeolian Tones.” For decades, engineers have been trying to prevent VIV from
damaging offshore equipment and structures. By maximizing and exploiting VIV
rather than spoiling and preventing it, VIVACE takes this ‘problem’ and
transforms it into a valuable resource for mankind.

The system, conceived by scientists at the University of Michigan, is called
Vivace, or “vortex-induced vibrations for aquatic clean energy”.

Michael Bernitsas, a professor of naval architecture at the university, said it
was based on the changes in water speed that are caused when a current flows
past an obstruction. Eddies or vortices, formed in the water flow, can move
objects up and down or left and right.

“This is a totally new method of extracting energy from water flow,” said Mr
Bernitsas. “Fish curve their bodies to glide between the vortices shed by the
bodies of the fish in front of them. Their muscle power alone could not propel
them through the water at the speed they go, so they ride in each other’s wake.”
Such vibrations can cause damage to structures built in water, like docks and
oil rigs. But Mr Bernitsas added: “We enhance the vibrations and harness this
powerful and destructive force in nature.

“If we could harness 0.1 per cent of the energy in the ocean, we could support
the energy needs of 15 billion people. In the English Channel, for example,
there is a very strong current, so you produce a lot of power.”

Engineers are now deploying a prototype device in the Detroit River, which has a
flow of less than two knots. Their work, funded by the US Department of Energy
and the US Office of Naval Research, is published in the current issue of the
quarterly Journal of Offshore Mechanics and Arctic Engineering.

This new technology along with all the other exciting developments in Hydropower
mark out 2008 as a landmark year. It should be a very exciting 2009.
If any readers know of any projects, companies, or technologies that I have
failed to cover here, please let me and all our other readers know about them
using the comments.

 

Promoting Green Building Design, Construction and Operation, Sustainable Living,
Clean Technology, Renewable Energy Resources and Energy Independence