The Oil Drum: Europe

I am appalled that the Severn Barrage scheme has not found favour. If we are going to get renewable energy up above the miserable 20% in 2020 level trumpeted by the report we need all the sources we can utilise. We need them both for the total quantity and to even out the variability that renewable resources have. Electricity needs to be generated to meet the demand second by second as it peaks and falls. Without any energy storage scheme on a TWhr scale we will need to keep conventional generating plant on standby or built massive excess renewable capacity and shed it when not needed. This is a problem that is trivial at the 0.2% level of renewables that we have now but rises to dominate the economics if we could get the figure up to 50%.

Tidal power is predictable. A double pond scheme with one pond  filled at high tide and one emptied at enables the generation to match demand peak, effectively combining generation capacity with storage. With this and as much other renewable capacity as we can build we can up the renewable share

To get an idea of how great a resource the Severn is, consider that the 1998 single barrage scheme would produce 17TWhr per year. The largest of the lagoon systems favoured by Friends of the Earth would generate 24TWhr per year. This is equivalent to the output of 2150 of the very largest 3MW 100m diameter offshore turbines at a 30% load factor for the barrage and 3030 of them for the lagoon system. For the 200kW 24m diameter turbines common onshore operating at 25% load factor the figures are 39000 turbines for the barrage and 54800 for the lagoons.

Using Sanyo's best 200W 1.18m² solar photovoltaic panels at 10% load factor you would need 97 million panels for the barrage and  154 million panels for the lagoons.

There are drawbacks and environmental costs on all energy schemes. The lagoon scheme has lower environmental costs but uses much more ballast or concrete. If we turn down every new scheme because there are some disadvantages we will be left with the default option. Conventional oil will peak and decline. For a couple of decades a frenzy or development of filthy alternatives such as tar sands, oil shale, Venezuelan super heavy oil and coal to liquid conversion will struggle to fill the gap before that fails but not before pumping enough carbon dioxide into the atmosphere to ensure climatic disaster. We will be left in an economic and environmental calamity.

We desperately need tidal power and the Severn is the second  best site in the world.