Sunday, October 07, 2007

Wave Energy to Power Desalination?

Perth is the first Australian city to have its drinking water partly supplied by desalinated seawater. A 45 GL/year plant was constructed and began operation at Kwinana, 40 km south of the city in 2006. Since then, the West Australian Government has announced plans for a second plant to be sited 155 km south of Perth near Binningup and to produce another 45 GL/year desalinated water by 2011.

Among the major issues with seawater desalination is the necessary energy consumption and the associated greenhouse gas production and cost impacts. The Kwinana desalination plant is powered from the local power grid. While the grid is predominantly supplied by coal-fired power stations, the equivalent energy required for the plant has been formally off-set by the construction of a wind-farm about 260 km north at Cervantes.

After plans for the second (Binningup) seawater desalination plant were announced, a West Australian company began vigorously promoting a new energy-supply technology, which is currently under development. The company is Carnegie Corporation and the developing technology is named CETO, -possibly after the hideous sea monster from Greek mythology (or perhaps there is another explanation for the name!).

The CETO Technology is actually owned by the London-based Investment Company ‘Renewable Energy Holdings Plc’ (REH). However, CETO is an Australian designed and developed technology. Much of the development has been undertaken (and continues to be undertaken) by the Perth-based company ‘Seapower Pacific Pty Ltd’. REH collaborates with Carnegie Corporation on financing CETO development in the Southern Hemisphere.

CETO is designed to harness ocean wave energy by using it to pressurise seawater and transport it onshore. The energy from the pressurised seawater can then by utilised by pushing the water through a reverse osmosis membrane (to produce desalinated water) or recovered by using it to run a turbine (to produce electricity).

The technology behind CETO is relatively simple. A buoyant bladder is restrained just below the sea surface and moves in an elliptical path as a result of wave-action. The bladder is connected to a piston which moves inside a narrow pipe fixed to the sea floor. The movement of the bladder pulls the piston up and down, producing pumping forces. These pumping forces are then used to drive pressurised seawater to shore via a pipeline.

Proposed CETO Wave Farm (© SeaPower Pacific Pty Ltd)

Plans are currently underway for a pre-commercialisation pilot-scale trial of CETO at Fremantle (WA) during 2007-2008. Based on the success of this trial, it is hoped that the first full-scale implementation of the technology can be developed during 2009-2011. Carnegie Corporation expects that this timing is just right for CETO to be employed for Perth’s second desalination plant.

The possibility of using CETO to power the future desalination plant was recently discussed in a short article appearing in CSIRO’s Ecos Magazine. The article quoted Phillip Jennings, Professor of Energy Studies at Murdoch University pointing out that while the technology is exciting, it is currently experimental and untested on a large scale:

‘Currently, the government is looking for an assured water supply,’ says Professor Jennings. ‘If the new desalination plant is not reliably producing clean drinking water by the target date, there will be a shortfall in Perth’s water supply. ‘First, CETO would need to prove itself at a smaller scale for a use that is not as critical as Perth’s drinking water supply. The company needs to demonstrate that the technology would be cost-competitive at a larger scale with other energy sources, such as wind power.’

A recent independent technical appraisal of CETO was undertaken for Renewable Energy Holdings in the UK. It noted “…Even with this price advantage, the CETO device will require financial support either through capital grants at the front end or through ongoing support as is available through the Renewable Obligation arrangements in the UK.”

As a whole, Australian governments have generally been very poor at investing in renewable energy technologies (why would they when burning coal is so cheap?). In order for a technology like CETO to be fully developed and commercialised, it is likely that either some government incentive will be required, or that the Australian population simply demand (and be prepared to pay for) clean energy alternatives.

Of course, one government intervention that would drastically improve the competitiveness of renewable technologies overnight would be the implementation of a carbon tax. Even the indication that such a tax would be instituted some time in the future would stimulate research and development. But which Australian government would be so foolish as to implement something that would be so vigorously opposed by the lucrative fossil fuels sector?

An alternative strategy is to sit back and let innovative Australian technologies be commercialised by overseas companies and then Australia can contract those companies -at significant cost- when we finally decide that we need the solutions that they provide. This is the model followed for hollow-fibre microfiltration membranes currently being installed in advanced water treatment plants around the country.

The independent technical assessment of CETO identified the West Australian coast as “an ideal location for the [first full-scale implementation] due to the high and constant wave energy (waves over 2 m occur 90 % of the time) that occurs along the south west coast”. However, ultimately, the assessment authors concluded “that a good commercial project test site may be in Northern Ireland, where there is economic support available for renewable energy projects in terms of the NIROC, combined with a good wave energy resource”.


The above text may sound pessimistic about Australian inclinations to support the development of innovative energy sources. However, stock exchange investors have a solid reputation for their collective ability to predict future events and they appear to be optimistic.

The Binningup desalination plant was announced by the West Australian Premier on May 15 2007. From that date over the next four weeks, the Carnegie Corporation share price rose from around 3.5 cents to more than 20 cents. It has since corrected to around 13 cents, but it is still an impressive sudden rise.

The red line is the share price, the burgundy line is the 20-day moving average and the blue line is the Australian stock exchange index “S&P/ASX 200”.

I wonder whether similar impacts were observed for other West Australian energy sector companies...

[Please note that I am not in the business of giving investment advice and nothing on this blog should be mistaken for such!]


Steve J. said...

Hi Stuart, nice blog!

I agree with Professor Jennings. CETO is exciting and probably has a bright future, but I think its very unlikely that the Western Australian government would take such a massive risk to power a billion dollar desalination plant with a still-developing technology that has not been tested on a large scale. The share price "correction" probably reflects investors thinking this through more carefully over time.

Perhaps the desal plant could incorporate a large-scale CETO trial, but still be powered by the electricity grid for its main supply. It would be an expensive exercise, but maybe Kevin Rudd’s government would be prepared to help fund it.

Stuart Khan said...

Thanks Steve,

A ‘non-committal’ large-scale trial sounds sensible to me. I would be particularly interested to ascertain the long-term reliability. Seawater is a corrosive environment and this will be an important challenge to address. What is the likelihood of the cylinders being seized by sand or barnacles? I suspect that it might take some time to confidently address these questions.

Anonymous said...

A carbon tax would be a disaster for the Australian economy!

Thomas said...

Hi Stuart

CETO looks like an interesting technology to get high pressure water to land. You talk about making fresh water using reverse osmosis. Nice idea, but some RO technologies are more efficient than others . . . Here at Modern Water plc (, we have some patented technologies that reduce the amount of energy (or pressure) required to drive the RO process (lower kWh/m3) by over 30%. We are also looking for projects to invest in within Australia. Can you suggest anyone that we should talk to?

Thomas Yeung

Stuart Khan said...

Hi Thomas,

I took a quick look at your website, but couldn't find any details regarding the RO technology that you refer to. As you would know, there is considerable interest in reduced-energy RO for desalination. Much of the recent progress has been attained by modifications to the membrane zeta potential in order to optimise electrostatic rejection of negatively charged ions.

There is a huge amount of work going on with desalination in Australia presently. Most of the major projects tend to be tendered for by consortia of 3-5 companies, each bringing various skills and/or products to the table. As a membrane supplier, I would suggest that you make your products known to the large international engineering companies involved with desalination plant construction. That way, you may be able to participate in a tender suitable for your product.

clay said...

Hey Stuart,

I'm doing a project in one of my business classes. We need to come up with an idea for a water plant in the middle east. I found a few articles talking about utilizing wave energy to power desalination plants. The plant would be located in Israel, so the only body of water you would be able to utilize is the Mediterranean. Are the waves generated in this area a feasible source of energy?

Anonymous said...

amazing !!!

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