Letter: Deeply dippy

Professor Andrew Porteous
Saturday 23 April 1994 23:02 BST
Comments

Your support helps us to tell the story

From reproductive rights to climate change to Big Tech, The Independent is on the ground when the story is developing. Whether it's investigating the financials of Elon Musk's pro-Trump PAC or producing our latest documentary, 'The A Word', which shines a light on the American women fighting for reproductive rights, we know how important it is to parse out the facts from the messaging.

At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.

The Independent is trusted by Americans across the entire political spectrum. And unlike many other quality news outlets, we choose not to lock Americans out of our reporting and analysis with paywalls. We believe quality journalism should be available to everyone, paid for by those who can afford it.

Your support makes all the difference.

PETER BOND'S 'Quest to harness power of the deep' (Business, 17 April) quotes a 7.5 per cent efficiency for the Ocean Thermal Energy Conversion (Otec) plant. This 7.5 per cent is the maximum theoretical or 'Carnot' efficiency. If a comparable Carnot efficiency calculation is performed for a coal-fired power station, the figure is approximately 55 per cent. As coal-fired power station have efficiencies in practice of 35 per cent (due to unavoidable losses in the real world of engineering) the Otec plant could be expected, on a pro rata basis, to have an actual efficiency of only 4.7 per cent.

As two-thirds of the energy output is needed to pump the sea water around the plant, the net efficiency could be as low as 1.5 per cent. This does not leave much room for error or for recovering the substantial capital costs of such a project.

Professor Andrew Porteous

The Open University

Milton Keynes

Join our commenting forum

Join thought-provoking conversations, follow other Independent readers and see their replies

Comments

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged inPlease refresh your browser to be logged in