June 08, 2008
Trial Of Offshore Floating Wind Turbine In Norway
A Norwegian fossil fuels company is going to try to use technology developed for offshore drilling to put up a floating offshore wind turbine.
The notion of floating wind turbines far offshore may have come a nautical mile closer to reality late last month, with the announcement of a collaboration between Norwegian oil and gas producer StatoilHydro and Germany's Siemens, a major wind-turbine producer. The new partners plan to install what could be the world's first commercial-scale wind turbine located offshore in deep water. StatoilHydro has allocated 400 million NOK ($78 million) to floating a Siemens turbine in more than 200 meters of water--10 times the depth that conventional offshore wind-turbine foundations can handle--atop a conventional oil and gas platform.
They will use a standard Siemens 2.3-megawatt wind turbine and a spar buoy very similar to what floating oil drilling platforms use. Initially they expect the electric power to be as expensive as solar power (i.e. very expensive). But they think they can get the costs way down.
What I wonder: How much of the higher cost is due to the cable that brings the electricity to shore? That part of the cost doesn't seem very amenable to cost reduction in the short to medium term.
Again, in situ use may be the answer.
How big do electrically-driven ammonia production plants have to be?
PS: The Norwegians have done work on direct electrolytic synthesis of ammonia for small scale use of hydropower.
Regards ammonia production: At what price of electricity and what price of natural gas does electricity become cost competitive for ammonia production?
Granted, the electricity right at the spot where it gets generated will be a lot cheaper than electricity delivered somewhere else. But ground-based wind turbines are going to generate that electricity at a lower price than sea-based wind turbines.
Where I can imagine wind turbines some day getting used to produce ammonia: The Aleutian Islands. Few people. Large amounts of wind. Why not put the wind turbines there on the ground where it is cheaper? Then the ammonia can be sold to Canada, the US, Mexico, and East Asia. Big markets.
If you want to use electricity onsite, I would think aluminum would be the answer - it always migrates to sources of cheap power, like hydro.
Aluminum requires constant power. It also requires heavy duty capital plant. It certainly doesn't work in offshore floating turbines. Even on the Aleutians I wonder whether it could make sense.
The cable cost will be like other costs and fall fast if enough projects are built. I remain a little dubious about offshore wind due to corrosion and construction/capital cost. Even so there is no reason to expect cost reductions when volumes and experience increase.
A wind farm would have two cabling costs: the connection to the land, and the connection of the generators to a central node. It is easy to see that the final size of the farm will dictate the capacity of the connection to land. Sizing knowledge also helps in choosing the best design for the cable web connecting the individual generators.
As some suggest, it might be better to shift some specialized material (aluminum?) production or manufacturing to offshore wind farms. It would depend greatly on the cost of moving the inputs to the platform. In most cases it is going to be cheaper to move electricity rather than raw materials.
"The average natural gas consumption for anhydrous ammonia production is approximately 33.5 million British thermal units (MMBtu) per ton."
= 293.072 kWh
and assuming the cost of ammonia is almost all energy and that the energy cost of a mass of ammonia is about the same with (ignoring ratios) CH4 -> H2 + N2 -> NH3 vs H2O -> H2 + N2 -> NH3, then it takes about:
= 9817.92 kWh/ton
of electricity to produce a ton of ammonia.
So when the price per ton of ammonia rises above the price of about 10MWh you have a good case for going to electric generation of ammonia.
I do not think the calculation is that simple. We have inefficiency in doing electrolysis to generate the hydrogen to attach to the nitrogen.
However, the the cost of anhydrous ammonia is around $1050 per ton.
10 MWh: That's 10,000 kwh. Well, at 10 cents per kwh that's around $1000. So we are in the right pricing neighborhood. But I wonder about the efficiency of electrically driven ammonia production.
True but you have to also consider that when the Haber process reaction energy is from electricity rather than methane combustion, you have more physical chemistry options and you may therefore overcome the electrolysis losses. I don't think the usual, methane combustion powered Haber process is any more energy efficient than electrolysis.
"Aluminum requires constant power. It also requires heavy duty capital plant. "
I believe that aluminum needs trickle power to stay hot, but not full-load - I believe some aluminum production happens primarily at night. I'm not sure about the capital plant - is that a weight concern, or utilization? Some floating oil platforms look pretty heavy.
I think oil platforms are small compared to an aluminum smelter. Better to build on an Aleutian island if wind turbines ever become cheap enough to power the aluminum industry.
One problem with switching to electricity for chemical production is that a large fraction of electricity is generated by natural gas and coal. We can expect electricity to go up in price as users of oil switch to natural gas and coal as cheaper per BTU. That'll drive up natural gas and coal prices.
We will need a lot more nukes, wind turbines, and cheaper photovoltaics in order for electricity to gain a big cost advantage over fossil fuels to drive chemical industries.