HYDROKINETIC ENERGY AT THE CROSSING

One of the things that draws people to the study and development of New Energy is an intuition about a future that is becoming every day more palpable. In an assessment of the progress made by hydrokinetic (wave, tide and current) energy, a pioneer in the field described that intuition.

Tom Denniss, founder/former CEO/now Chief Technology Officer and Executive Director, Oceanlinx: “At some point in the future, all energy consumed on the earth will be derived from renewable sources. The timeframe for this fundamental move from fossil to sustainable fuels is debatable, but the end result is not.”

It probably isn't necessary to explain why Denniss is right but here are his reasons: (1) Climate change, and (2) the using up of non-renewable energy resources (oil, gas, coal and uranium for nuclear energy).

According to Denniss, wave energy potential capacity is 30 terawatts, twice the current world energy consumption.

Denniss pointed out how varied the state of hydrokinetic energy devices is in terms of power off-take, mooring and basic operation: “No two devices seem to look the same. Indeed, some are as different as a hairdryer is from a lawn mower.”

The single consistent fact of hydrokinetic devices is the maximum capacity limit of 1 megawatt, due to the physics of waves.

Wind energy saw a convergence from various technologies to the three-bladed, horizontal-axis turbine. Hydrokinetic energy may never have such convergence because of fundamental differences in the resources at varying locations and under varying conditions.

Tide energy potential capacity is estimated at 1/10th of wave potential. That is 20% of current human consumption – certainly worth making the effort to harvest. Tide energy is consistent and predictable and therefore an important adjunct to intermittent New Energies like wind and sun.

There are 2 kinds of tide technologies, barrage and stream. There are projects just getting started and in planning. The technologies remain unproven and have limited acceptance. Technical issues remain.

For both wave and tide hydrokinetic energies, the still-distant goal is the same: Grid parity.

Grid parity is the price point at which any New Energy-generated electricity can be produced at a competitive price with the traditional energy sources (fossil fuels and nuclear) now used to generated the bulk of the world’s electricity.

Presently, given the right circumstances, building wind installations, solar power plants and geothermal power plants is price competitive with the building of traditional power.

Hydrokinetic energy is at a crossroads: Some technologies will achieve higher levels of productivity and develop economies of scale that will move them toward grid parity.

Denniss, Oceanlinx: “The survival or demise of a technology is a tenuous thing. For any new technology with potential, it is vital that funding does not dry up at the critical time when lessons have been learned and mistakes corrected…A few wave and tidal technologies are on the cusp of reaching this fork in the road to commercialisation or demise. Once the former is attained, the road will quickly become a highway.”

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Ocean power reaching a fork in the road
Tom Denniss, October 2008 (Australian Academy of Technological Sciences and Engineering via Science Alert, Australia & New Zealand)

WHO
Tom Denniss, founder/former CEO/now Chief Technology Officer and Executive Director, Several wave energy companies near commercial production (Oceanlinx; Pelamis, Wavedragon, OPT, Oceanlinx, CETO, BioWave); Some tide energy companies near commercial production (Marine Current Turbines (MCT), Verdant)

WHAT
Hydrokinetic energy is at a crossroads. Some technologies will emerge as price competitive; some will fail.

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WHEN
- Denniss founded Oceanlinx in 1997.
- The life expectancy of oil is estimated to be decades. For coal, it is a few centuries.
- Tide energy technologies have been in commercial existence for many decades but there continues to be no technology convergence.
- Convergence of wave energy technologies may (or may not) occur over time.
- Barrage systems have been used to capture tide energy for centuries.
- Tide stream technologies are new and have never been used commercially.

WHERE
- Most companies at or near commercial scale hydrokinetic energy production are in Europe and North America (Pelamis, Wavedragon, OPT). 3 are in Australia (Oceanlinx, CETO, BioWave).
- A tidal barrage has worked at Mont Saint-Michel, France, for years. A larger one was planned for the Kimberley region of Western Australia but cancelled due to concerns for the intertidal zone.
- Some companies have operating tide projects in the Northern Hemisphere (Marine Current Turbines (MCT), Verdant) but there are none in Australia.

WHY
- Denniss invented the core technology commercialised by Oceanlinx
- A shift to 100% New Energy will come because of 2 reasons, climate change and the use of non-renewable reserves.
- The estimated wave energy potential capacity of 30 terawatts is twice the world’s current power usage.
- Hydrokinetic energy devices range from pneumatic to hydraulic, fixed to floating and buoyancy to pressure to gravity.
- Maximum output is 1 megawatt, limited by the physical constraints of the waves’ period and length, and the need to avoid the destructive interference of the waves with one another.
- Scale-up to greater capacities is done by adding more devices to a wave installation.
- There are 2 types of tide energy devices, barrage and stream.
(1) Barrage: The in-flowing tide fills a basin that is prevented from emptying with the out-flowing tide by a barrage which is opened to create an out-flow that turns a turbine to generate electricity. At low tide, the process reverses.
(2) Stream: Uses underwater turbine technology.
- Some wave and tide technologies are on the verge of achieving prodeuction capacities that will make them price competitive.

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QUOTES
- Denniss, founder/former CEO/now Chief Technology Officer and Executive Director, Oceanlinx: “Perhaps the most underexplored, and certainly the most under-utilised, is that of ocean energy.”
- Denniss, Oceanlinx: “A new industry, such as marine energy, will initially attract interest, followed by funding, followed by experience. The experience inevitably includes some failures, which tends to dampen the initial enthusiasm…[that] can result in a potential funding gap at a crucial stage in the technology’s technical and commercial development. For those technologies that can bridge this gap, the road to success becomes much smoother. Those that cannot bridge the gap will disappear…”