Tidal
From Energy-Experts
Here attached is my attempt to get it aired more...
What I didnt get to say was that the barrage may be seen as just a pumped stoage facility for a new nuke at Hinkley-which will ocasionally generate some tidal output in sync with demand, as a bonus.
If we are to have 20GW of nukes and baseload is 20GW, if the barrage does fire off at night with 8GW we wont need its power - or for that matter wind power's input then.
Dave E
From: Dave Elliott
Sent: 13 June 2008 18:41
To: claverton
Subject: [claverton] Severn Barrage
As someone who has studied this in depth over many years, what worries me is not so much the massive environmental impact of blocking of an entire estuary, which WWF, RSPB etc see as imposiible to accept, but the strategic issues.
It is claimed that the 8.6 GW Barrage would generate17 TWh p.a., which is 4.6% of UK electricity. Unfortunatley however, much of the time this electricty could not actually be used, since it would be produced at night time when demand is very low. At other times, when demend is high, the tidal cycles may mean the barrage can't deliver any power at all. It just fires off for a couple of hours or so, twice every 24 hours or so, on a shifting cycle, and also only occasionally delivers at full power, due to the spring-neap tide cycle. The practical result of all this is that, as the Sustainable Development Commission admitted, it would only save 0.92% of UK carbon emissions. Not much for £15 billion. Almost any other renewable energy option would be vastly better in carbon saving terms. Also in direct conomic terms , as the recent Frontier Econocmics study done for WWF, RSPB et al found.
For example a system with many tidal farms made up of small (1-2 MW) tidal current turbines installed in the sea bed at various sites around the coast could generate the same amount of total electricity at much less costs and with almost no environmental impact. And , crucially, since the tides are delayed by hours at each point as you move around the coast, the peak power output from the turbines would be staggered, so that you get more or less continously available power from the system as a whole.
Put simply the barrage is a large invasive, expensive inefficient and inflexible option, whereas what we need is smaller decentalised flexible low impact technologies.
It gets worse. It may be that the barrage may be seen by BERR as a 'pumped storage' facility for a new 3.6 GW nuke at Hinkley- one which will lso ocasionally generate some tidal output in sync with demand, as a bonus. Nuclear plants have to be run more or less continuously at full power, in order to be economic, and for techncal reasons (you can't wind them up and down easily), but demand for their power is low at night. This power can be used to pump water behind the barrage, and this extra head of water can be used later to generate power again, making the economics of nuclear look better. Moreover, tragically, we may have up to 20GW of nuclear power plants in place by the time the barrage is could be built, so then, even when the barrage did fire off in synch with demand, we wouldn't be able to use its power very often, except on those rare occasions when it provides power at peak demand times.
