Introducing ... the Ocean Source Heat Pump?

A few months ago I put up a post about how a Ground Source Heat Pump works. But here's an interesting twist on the same idea: the Ocean Source Heat Pump. *

As David Mackay has pointed out, the risk with ground source heat pumps is that you eventually extract enough heat to freeze the ground around you. Essentially, the ground is a good store of heat because of it's low thermal conductivity, but for the same reason it's also hard to replenish the store. Which means that if you're constantly take heat from the same hole in the ground, eventually you get to a point where you've taken it all.

Of course in the ocean you have a different situation, first of all because you're working with a liquid heat store, and secondly because you can more easily float your power station around to different locations. In the video clip I have linked to above, Dr Ted Johnson, Director of Alternative Energy Development at Lockheed Martin who are developing the prototype, says:

"I dream of thousands of floating OTEC ships, roaming the seas of the world and providing an inexhaustible supply of clean energy, fuel and water for all people of the world"

Well, it's a wonderful vision and I agree with that. But presumably the problem is how to store the electric power that the floating heat pumps generate, or more precisely how to do that without destroying the economics of the thing completely. Bear in mind that electric storage is REALLY expensive: even a small 24 KWh battery for a state of the art electric car costs about $10,000 - $15,000, and Ted is talking about ocean pumps with 10 or 100MW capacity. So even without having done the math on this (which at some level is against all my principles), I'd assume that the energy storage costs do this project in.

BUT, hang on a moment. Things would be different, wouldn't they, if you had something useful you could do with all that power right there in the ocean? And if you think for a minute about the applications of clean energy generation in close proximity to the ocean... well, it doesn't take long for desalination to jump to mind, i.e. the highly power-intensive conversion of salt water to drinking water.

Perhaps Dr Johnson has come up with something unbelievable after all, the answer to the world's water wars of the future. And clean water is of course, much easier to store and move around than clean energy.



* Of course, I noticed that this technology is not exactly a heat pump, but it's a close cousin. So let's get on with it and not be too pedantic.

Energy Flow Chart 2009

I've been meaning to post this for a while. If you've been enjoying the blog so far, then you should enjoy this (which comes from here and uses these as units) without further explanation. Click on the image for a full size view. 

It's not a tube map.

Our electricity could be gone for months

Earlier this summer I blogged about High Impact, Low Frequency events, unlikely occurrences but which could knock out the power grid. It sounds fanciful, but it's a real issue - dangerous electro-magnetic pulses could be caused by solar flares, electro-magnetic storms or by man-made nuclear explosions at high altitude.

So, very pleased to hear  Radio 4's Today Programme covering this topic today, with an interview of Avi Schnurr at the EMP Coalition. It's a risk we face that didn't exist a hundred years ago. The interview has not been posted yet, but should appear soon on the i-player (but for UK internauts only I believe).

High Impact, Low Frequency?

The BP oil spill has got us all thinking about low frequency, high impact events. But some people have been thinking about these things for quite a while, including the team at NERC - the North American Electric Reliability Corporation. Who knew such an institution even existed? Their job apparently is to worry about unlikely events that would be really, really bad if they ever came about.

The latest NERC report includes a detailed section on geomagnetic storms:

The analysis indicates that the [geomagnetically induced current] in over 350 transformers will exceed levels where the transformer is at risk of irreparable damage...  Such large scale damage could lead to prolonged restoration and long-term chronic shortages of electricity supply capability to the impacted regions, arguably for multiple years.

In other words, a really big storm could roast enough components (70-80% of transformers in some states) to put the lights out for years. A version of this event happened in March 1989 and knocked out parts of the Canadian grid for most of a day. But since then, the grid has been developed in ways that make it more vulnerable than before: essentially, higher voltage transmission means geomagnetically induced currents can travel further and do more damage.

From a different angle, we could perhaps get a similar effect from a high altitude nuclear explosion. Here's a photo of the last time we had a go at one of those. This one was 400km in the air but the electromagnetic pulse was enough to blow out the streetlights in Hawaii, 1500km away.

(This is the 1962 Starfish Prime explosion.)

Vive la France!

Congratulations to France, which has de loin the lowest per capita CO2 emissions in the G8. Good news for those who think the future is nuclear. Of course some of us think that the future will not be nuclear. If anyone has a G8 league table of hazardous waste per capita please post the link.

PS I am guessing France benefits from a bit of warm weather too, from a quick look at the Canada column. The dataset comes from here if you are after the source.