Engaging Energy

Round three of the UK offshore wind tender process totaled 32.2 GW of nameplate generating capacity. That’s a lorra lorra windmills and well above the expected 25GW power output. Lets be middle of the road and say for the sake of convenience that 3.22 MW turbines exist, that’d be 10,000 turbines located between 22km and 190km from the nearest landfall.

The London Array has started to hand out contracts. Nexans, the submarine cable specialist, has won the power export (windfarm to shore) cable contract. It is 100M Euro for 4x 53km long 150kV capacity copper cables to carry up to 1GW of power from 175 turbines.

If we do a quick bit of maths on that for 32 times the power, roughly twice the distance and 57 times the number of turbines, if the Round Three windfarms use the same technology as the London Array, the export cables alone should cost in the order of 6.5bn Euros (not including inflation or commodity risk). Using my previous estimation of the intensity of copper use in wind power, 10,000 offshore turbines and their associated cabling will use around 310,000 tonnes of conductor grade copper. Copper’s current price is around US$7,200 per tonne giving an embodied copper cost today of US$2.23bn. By the time these windmills get built, that figure looks cheap to me.

Perhaps that’s why the North Sea Supergrid got a bunk up the probability ladder by the nations next to the water. For an estimated one-off cost of 30bn Euro you get a ‘local’ connection, cutting the need for those expensive connections to shore and you get the ability to load balance using Norway’s hydro power excess.

If I had an extra billion or two I’d be looking at building a submarine cabling capacity right now. Not just the cable factory but the cable laying vessel and some upstream capacity in copper recycling. It’d be nice to think that we’d be at super conducting cables for this job, but at 6,000km total length and multi-GW capacity I’m not sure that the tech will be with us in time. Looks like HVDC instead, shame.