On Renewables Without the Hot Air Estimnates of Off-Shore Wind Generation

[danieldwilliam]

Further to a converation elsewhere I've re-skimmed some Renewables Without the Hot Air estimnates on offshore wind. WOTHA estimate of usage is 195 kwh per person per day. Estimate of shallow offshore wind production is 1 kwh per person per day and deep (25-50m) offshore production at double that, 32 kwh /day / person. Total is 48 kwh /d/p.

Shallow area 40,000 km2 with energy denisity of 3W / m2. 1/3rd of shallow waters to be used. Some vague mumbling about shipping and fishing getting int he way.

Based his assumptionson 3MW turbines. 7MW seems standard now. I reckon we'll see 10-12 as the standard in a few years. Not sure what that does to the energy density by area but it can't hurt.

I've always thought his modelling of the economics was niave in that it did not allow for things to become feasible once the cost started falling. When something becomes cheaper to do than the alternatives it all gets done.

I reckon you could double the estimated output by increasing the turbine size, tower size and increasing the area. That gets you to 98 kwh /d/p.

Use of floating turbines in 50m+ deep waters should get you to double that 98 kwh /d/p or about 200 kwh per person per day.

Building all of this is not a trivial economic or engineering task. I think building solar PV in Morocco and shipping the power north will prove cheaper and quicker.

Comments

[andrewducker]

Thank you!

So the figures look much better than he thought because the technology has greatly improved.

(Shame he's not about to update the book)

[danieldwilliam]

I think he would consider me to be too optimistic. However, the tech has moved on in terms of the size of the turbines and towers.

I'm not sure what exactly was driving his decision to only include 1/3rd of the available sea area. Shipping lanes and fishing but I don't think there was much thought beyond "hey, shipping and fishing will need some space".

The real change in my mind is the floating offshore wind technology at eg Hywind.

My model for these things is that new ways of doing things start costing eye-watering multiples of the alternatives. With a bit of development you might start seeing a way to getting the cost down to a mere order of magnitude more. If there are not any fundamental barriers implicit in the physics the cost reduction becomes a function of learning curve effects, scale economies the interactions with adjacecent enabling technology. Once you get yourself on the cost reduction path you are likely to come out at as cheaper than the existing alternative over time.

So key barriers are fundamental barriers in the physics and whether the investments required by earlier adopters to get the technology on a cost reduction path are ever going to be worth it.

CCS for me fails the two tests because it's difficult to see a way of burning fossil fuels and sequestering the carbon that releases more usable energy than just sourcing it from solar PV and even if you could solar PV is almost certainly going to chase you down the cost curve.

Off-shore floating wind passes the first test. There doesn't seem to be a physical limits that stop us building the turbines we would want. Looks like the technology is on a beneficial glide path for costs.

I still think solar PV and big cables will end up being cheaper.

It is a shame he's not around to update the book. I'd be interested to see if his fundamental thinking changed in light of the different economics.

[hilarita]

There's probably also some assumptions about leaving space for birds and not disrupting too much of the maritime environment.

[danieldwilliam]

He talks a bit about birds but I didn't notice an explicit assumption about them.

But he's generally taken quite a conservative line on assumptions -which is fair enough given that others have probably taken too optimistic a set of assumptions.

[cmcmck]

They've been experimenting up off Orkney with wave turbine power for some years. The EMEC platform is just off the island of Eday and we'll be spending time up there again this year.

[danieldwilliam]

Aye, my dad has done a bit of work on them.

I'm keen to see them deployed but I worry a bit that the technology has arrived too late and the use case is a little too narrow for them to see widespread deployment.

I think we are at the point where for the next twenty years, if the technology isn't already cheaper than coal the answer to the question, "what power generation technology should we use" is going to be build some solar PV.

However, the cost of deployment might be reducable through the use of robots.

[armiphlage]

I think wavepower still has a lot of potential. Tens of kilowatts per metre of coastline! I personally prefer submerged pressure-differential systems, rather than the floating systems. Easy to deploy, not going to be damaged by storms, won't interfere with shipping, and if you equip the modules with standoff supports so they don't settle directly on the bottom, the impact to wildlife is minimal.

The few projects being developed seem to be going for large air bladders connected to turbines to draw off the power. I think this would be an ideal place to use piezoelectric energy harvesters connected to a huge array of much smaller air bladders. No rotating parts, and the system will keep working if some of the bladders get punctured by curious sealife.

[danieldwilliam]

For me wave power enjoys some important economic advantages.

1) the units are small, so they can be produced in factory, in volume, giving rise to economies of scale and learning curve effects which should drive down the cost.

2) they can piggyback in part on the improvements in infrastructure and technology created by offshore wind

3) they seem amenable to robotic installation because they are large volumes of small generators.

But I think they have been beaten to the punch by solar PV which has a better scalability because solar PV units are smaller (more volume, more learning) and have a bigger and more readily accessible market. Putting up a solar panel in the desert looks to me to be easier than putting anything in the sea.

I do think we'll see solar PV sitting in a virtuous spot for the next ten years where production capacity of the panels increases and improves, deployment increases year on year and the cost drops by 2- 4% a year.

I hope I'm wrong. Broadly, I like the idea of having lots technologies in the generation mix. What if solar PV causes a horrible industrial disease and that's all we've got. Closer to home as an employee of a maritime robotics company who lives in Scotland I'd love for a power generation technology that involves maritime robotics and a windy, wavy coastline to be economical. That's paying my pension.