The Potential of Ocean Power
3.24.09
Daniel
Englander, Senior Energy Analyst, Greentech Media
Ocean power is 832 times denser than the air flowing over wind turbines
as tidal waves are predictable up to the minute at least 100 years in
advance. Understandable and rapidly declining costs coupled with high
performance and output are the primary factors that will drive down the
levelized cost of energy for ocean power technologies in the long term. In
this report, Greentech Media and the Prometheus Institute for Sustainable
Development address the underlying fundamentals that will determine when
ocean power technologies will become competitive with other renewable and
traditional energy sources, what technologies will bring the industry to
that point, and how investment, government policies, and power sector buy-in
will drive the growth of this industry.
While today fewer than 10 MW of ocean power capacity has been installed
worldwide, we believe that in six years the industry has the potential to
break 1 GW of installed capacity on an annual market size of over $500
million. More than $2 billion will be invested in that time in commercial
production and installation. Based on current trends, a similar amount will
be invested in research, design and development during that time.
Ocean Power Technologies
Ocean power technologies occupy a unique space in the world of renewable
energy. The majority of devices are fairly new, notwithstanding the burst of
technology development that occurred from the mid-1970s to the early 1980s.
Designs from the first ocean power development boom focused largely on ocean
thermal energy conversion and salinity gradient conversion. Most current
designs have their origins in the late 1990s or early 2000s. Wave Dragon's
overtopper, the oldest of the modern technologies, was conceived in 1986 by
founder Erik Friis-Madsen as he watched water flow through the holes of a
reef on a Pacific atoll.
Despite their status as early-stage or emerging technologies, many in the
industry regard ocean power devices as an extension of technology developed
in the offshore oil and gas, wind power, and shipbuilding industries. In
fact, nearly every wave and tidal company has an engineer, designer, or
founder with a hydraulic or marine engineering background and many have
borrowed heavily from technologies and components developed in these
industries.
Technology transfer between traditional marine and wind industries and the
ocean power industry has allowed many companies to move rapidly into
advanced research and development. Compared with other renewable energy
sectors, such as solar or advanced storage where materials and chemical
research often consume a disproportionate amount of time and investment
capital, ocean power companies often dedicate a majority of their
early-stage work to combining mechanical and electrical systems and proving
device survivability and performance. As such, the development bottleneck in
ocean power often occurs in the scaling-up stage and not the device design
stage.
In 2006, the International Energy Agency identified 81 individual ocean
power projects ranging from university and government-backed research
programs to companies on the verge of commercial deployment. The United
Kingdom was the leading developer with 29 individual projects while the
United States was second with 13. Other leading countries include Australia,
Ireland, Canada and Norway.
Wave Power
Wave energy technologies are the most heavily researched and funded sector
in the ocean power industry. Out of the 35 companies analyzed in this
report, 24 are developing wave energy technologies. This is likely due to
the scale and availability of the ocean wave resource when compared to the
marine current and tidal stream resource. The potential to bring renewable
electricity to the nearly 50 percent of the world's population living within
60 miles of a coastal area is another factor driving the outsized
development of wave energy technologies.
The majority of companies developing wave energy technologies are working on
devices called point absorbers. Point absorbers resemble offshore buoys that
mark channels and measure environmental and meteorological data, though they
are much larger. These devices are researched and developed at a higher rate
than other kinds of wave energy devices because of their ability to absorb
energy from oncoming waves in all directions. Their behavior is much the
same as that of a cork in a bathtub, bobbing in reaction to multidirectional
ripples. All other wave energy devices are designed to absorb oncoming
energy from only one direction or dimension in space. Multidirectional
absorption, however, is not without its problems. The device must be tuned
to the wave climate in which it is submerged, or energy created will not
flow smoothly through the power take-off system. Some companies have
developed advanced tuning systems, while others have overlooked this
critical issue.
Tidal Power
Tidal energy technologies have received relatively less attention than wave
energy technologies, despite their comparative success in commercial
deployment and lab and in-water testing. Of the 35 companies analyzed in
this report, only 11 are developing tidal energy technologies. While
geography is a limiting factor in the deployment of tidal energy devices, in
the future this may be mitigated by some of the more promising aspects of
this method of power generation.
In addition to the obvious technology transfer possibilities from the wind
industry to the tidal industry -- the link here is much clearer than the
technology transfer link between wave power and the offshore oil and gas
industry -- tidal energy provides an exceptionally predictable source of
power. Since tides are a function of lunar phasing, it is possible to
predict incoming tidal power hundreds of years in advance.
Of all the renewable energy technologies, with the possible exception of
geothermal power, tidal power is the most predictable and reliable. This
could help in alleviating, though not solving entirely, the problem of
dispatchability that many power companies and utilities cite as a reason for
not adopting renewable energy technologies. The majority of tidal energy
companies are developing horizontal axis turbines. In many ways these are
analogous to both land-based and offshore wind turbines, and the general
shape, mounting and fixing technology, and power take-off system design are
essentially the same. There are, however, several critical differences: Size
is by far the most important factor separating horizontal axis turbines
operating in the water from horizontal axis turbines that harness wind
power. Tidal turbines generating 1 MW of power may have rotor diameters
roughly one-third the size of a wind turbine with a comparable nameplate
rating.
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