A Dream of Cable Beach

Capturing the power of the sea

My late Father spoke to me of the tides at Cable Beach and said there must be a way to harvest the moving of the ocean to generate power. He first saw Cable Beach near Broome during WWII. Over the night the sea seemed to disappear and it came back.

The tides are huge at Cable Beach but strategic globally.

Cable Beach – Tide out

Last night, at a function sponsored by Invest HK, I met Dr Bruce Poon of Mako Tidal Turbines. Dr Poon works in the design and manufacture of the next generation of turbines which harvest energy from the movement of water based on tidal movements. What Mako have been able to demonstrate that there is also energy which can be captured from currents. Dr Poon’s explanation of his work in the area and the global efforts made me read more. Perhaps the ocean and tide power was the next big things that Projects RH (see: www.projectsrh.com.au) in Australia and Tabatinga (see www.tabatingasg.com.au) in Asia and Latin America should be focusing on? I must admit as Dr Poon spoke, I was thinking of its application in the huge Colombian Pacific Port of Buenaventura which is noticeably tidal and is in an area of Colombia needing additional power.

Tidal energy is generated broadly in the same way as hydroelectric power. It uses energy generated by moving water to generate electricity. For me the simplicity of tidal energy is available n the ocean, in estuaries, canals.[2] Three thoughts are appealing:

1)      You do not need to build dams and block rivers. You are not taking water from other purposes.

2)      The flow and timing are highly predictable. The tidal cycle is two high and two low tides occur every 24 hours and 50 minutes.

3)      The water does not need to be pumped back after it has been used to generate power.[3]

4)      Turbines can be placed in lines. [4]

Given about 70% of the earth’s surface is water why do we not have vast arrays of turbines collecting another valuable harvest from the sea? It was originally cost and then perceived cost. Secondly, the real price of energy has risen and the cost of capture of tidal energy has fallen with improved technology, design and new materials

Because the Earth's tides are ultimately due to gravitational interaction with the Sun and the Moon coupled with the Earth's rotation, tidal power is practically inexhaustible. The impact of large amounts of tidal power on tilt of the earth and its rotation speed is negligible. Tidal power is rightly classified as a renewable energy resource.

The three ways commonly used to harvest tidal power are:

1)      Creating a tidal lagoon and capturing the energy as the water enters and leaves the lagoon.

2)      Tidal barrages – specialised dams with turbines

3)      Turbines attached to infrastructure – channels, bridges etc.

Tidal power has had enthusiastic supporters and investors in the 20^th Century with projects in US and Canada in the 1920’s and in 1960’s in France (Rance River estuary in Brittany – 24 * 10 MW but delivering an average of 57MW.

The 21^st Century has seen renewed energy and investment in Europe and Asia. South Korea’s Sihwa Lake Tidal Power Station, completed in 2011, is the world's largest tidal power installation, with a total power output capacity of 254 MW (but a 24.8% capacity factor due to running only one director for environmental reasons).[5] It is appropriate to see tidal power as a new form of renewable energy in the 21^st Century as they application has substantially changed with investors understanding that the capital and maintenance costs need to controlled (reduced) and it needs to compete based on production being over 50% of the time.

The outlook is particularly rosy. There are some predictions that profitable prototypes could be offered to the market in the early 2020’s.

What remains attractive about tidal power is it is predictable and like solar low ongoing cost. What is happening is that the designs are being simplified, capital costs lowered and technical efficiency being improved.

The work being undertaken by MAKO, and others, is seeing a tidal energy becoming able to compete on a level playing field making it affordable to install as well as profitable to invest in. What is pleasing for us to see is so much of the work is occurring in Australia, Singapore and Japan - each od which is surrounded by the great moving oceans.

By Paul Raftery (see www.paulraftery.com.au)

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[1] Source: https://www.google.com/search?q=cable+beach+photo&tbm=isch&tbs=rimg:CbxlS-Zf0f0NIjjX2Wkyg-pIshNEj1sx3FPUX66D7z4QDmY2y2N2YdD3DosVA9uQvost0apSk7F5DqUTseJ8wTCZ4yoSCdfZaTKD6kiyEYLUJ5llafHNKhIJE0SPWzHcU9QRxyur0g_1NYCkqEglfroPvPhAOZhEaDgcSsSvfNCoSCTbLY3Zh0PcOEaBfiRC_1BOaUKhIJixUD25C-iy0RLwCOZCIQh7cqEgnRqlKTsXkOpRGKbIwJ0l6RuSoSCROx4nzBMJnjEYpsjAnSXpG5&tbo=u&sa=X&ved=2ahUKEwj7vOH1o7HiAhWDrI8KHQ20CkoQ9C96BAgBEBg&biw=1261&bih=895&dpr=1#imgrc=19lpMoPqSLJ0sM: Accessed 23-05-19

[2] See: https://en.wikipedia.org/wiki/Tidal_power Accessed 23-05-19

[3] In Australia the so called “national battery”, the Snowy Mountains Hydro Scheme, can be called upon to supply power on demand. But to call it next time the water needs to be pumped back by coal fired power units. The Genex (Kidston) pump hydro project, in Central Queensland, uses solar power to pump its water back.

[4] See : https://www.mako.energy/news Accessed 23-05-19

[5] See: https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station, Accessed 23-05-19.