Thursday, 3 March 2011

Deep Green revisited

Back in February 2010 I did a blog post (click for link) about new developments in wind and underwater power generation technologies. They both used the tethered hang glider/paraglider concept to generate more wind power than conventional wind or tidal turbine systems by “flying” in a figure of eight pattern that increases the effect speed of the water or wind plus greatly increases the area (and thus the available harvestable energy) that can be covered by each generating unit.

Here’s an article in the Guardian online that revisits the Minesto technology. Briefly, their first sea trial will be held in Strangford Lough in Northern Ireland this summer (where engineers are already testing other other conventional tidal technology.




TonyTheProf said...

Tidal streams (which are regular) seem a far better way of exploting natural power resources than wind power, which seems very problematic in terms of being able to determine how much is available at any one moment, and thereby being able to meet transient peaks in demand.

I still think the real breakthrough will only come with some real investment and breathrough in energy storage.

At the moment, only pumped-storage reservoir systems seem commercially viable.

Nick Palmer said...

Molten sodium and/or "flow" batteries are feasible and economical now but this new development might be significant too.

new much cheaper storage battery

Looked at over a continent, the nature of low pressures (depressions) and anticyclones is such that the wind will always be blowing somewhere and a decent grid can spread the love around.

The idea that because wind power is transient it cannot power a grid is a bit of a canard. Firstly, no-one ever said that wind on its own is sufficient to replace the steady supply from fossil fuelled stations. A portfolio of technologies including concentrating solar, tidal, wind, anaerobic digestion plus storage could.

Here's a link to a paper that claims we could use "Wind, Solar and Water Alone to Power the World by 2030"

TonyTheProf said...

Perhaps for the UK; I can't see a huge potential for wind power in Jersey, however, because the wind simply isn't always blowing everywhere (although walking outside today brrr. it certainly felt like it)

The problem with transient demand is (a) where to dump excess energy when it exceeds exceeds current demand (b) how quickly alternatives can come on line if its flow decreases significantly; unles you want widespread blackouts.

And both really relate to the problem of storage. Actually I think water potential (in terms of using surplus energy to move it uphill) storage using dams is probably the best means of mass storage.

You also missed out nuclear in your portfolio of technologies.

Nick Palmer said...

Umm. I did say "and a decent grid can spread the love around"
- the grid we have now is optimised for large power stations with constant output. Not for sustainably sourced electricity where some sources can fluctuate.

In any event we have the same "fluctuation" problems at the moment with the conventional grid, only from the other side - massive nuclear and coal powered stations generate more at night than is needed locally so other smaller stations (often gas powered) have to throttle back, which they are designed to do as they have less "inertia".

If we had to use sustainable sources with the current grid systems the reverse would happen - at night and periods of low demand, the wind, tide, hydro, anaerobic digestion gas, solar concentrator etc would supply the night/lower load and "nimble" gas powered (could be AD gas or syngas) stations would throttle up for peak moments during the day. Just the same sort of problems as the ones we already solve but seen though the looking glass. Not a problem.

Water storage is OK but is expensive and probably not capable of much expansion except in those areas which are geographically suitable, quite a few of which are already used. Compressed air, silicon metal, flow batteries, compressed AD gas storage are all do-able. Future smart grids are planned to be able to utilise the battery systems of EV cars as a huge load stabilisation/storage resource.

A sustainable grid also recognises that giant power stations are rather an artifact of our giant consumer civilisation. Instead of having, say, 200 giant power stations supplying a country, we should substitute, say, 2000 much smaller CO2-Lite "stations" scattered around more evenly - not to mention 100s of thousands of home/hamlet sized fuel cell stations supplying the hamlets and exporting the surplus. Not forgetting millions of EV cars.

Such a situation would be massively more robust and would generate way more economic goodies than the current system, not to mention stabilising international relations because we would not be beholden to unstable fossil or nuclear fuel supplies.

BTW, I didn't forget nuclear, I excluded it. While a case can be made for GEN III/IV stations (if they can be demonstrated to work as the promise shows) as a solution to powering our current civilisation while reducing CO2 emissions greatly, the big problem is that this is just a one-dimensional answer to a multi-dimensional problem and therefore dangerously misleading.