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> What’s groundbreaking about the Hywind project, located in more than 300ft (90m) of water, is that the giant masts and turbines sit in buoyant concrete-and-st
by sradman 6y ago
> What’s groundbreaking about the Hywind project, located in more than 300ft (90m) of water, is that the giant masts and turbines sit in buoyant concrete-and-steel keels that enable them to stand upright on the water, much like a fishing buoy. The turbines’ nearly 10,000-ton cylindrical bases are held in place with three taut mooring cables attached to anchors, which lie on the sea floor.
> Currently the electricity they generate is often almost twice as expensive as near-shore wind turbines and three times that of land-based wind turbines.
- Aerroon 6y agoHow long would one of those have to generate electricity to make up for its own construction? 10,000 tons of concrete and steel probably cause quite a lot of CO2 pollution to make.
- cogman10 6y agoLast time I researched it, it came to about 1->2 years to pay back manufacturing energy. That was for land based turbines. Bigger turbines payed back faster. So 1MW was closer to 2 years while 3MW was closer to 1. The steel used was by and large the biggest energy cost.
- brandmeyer 6y agoSteelmaking's CO2 footprint is driven by energy costs, but concrete's CO2 footprint is driven by the chemistry of the commonly-used concrete production stages. It isn't visible in energy costs.
- sradman 6y agoPortland cement production, not concrete which consists of aggregate as well. There must be many trade offs in this design and one can imagine pure sand as ballast so the concrete plays some structural role. The sea floor anchor design and high voltage underwater cables also seem like hard engineering problems.
- sergeykish 6y agoStrangely each time I see a doubt about renewable energy quick search resolves it [1]. I've thought hydro produces least, no > At a dam in Brazil, where the flooded basin is wide and the biomass volume is high the methane produced results in a pollution potential 3.5 times more than an oil-fired power plant would be. A theoretical study has indicated that globally hydroelectric reservoirs may emit 104 million metric tonnes of methane gas annually [2]. There is no green gas free energy only different cost, even nuclear. But maybe we can reduce emissions and some day catch them back. [1] https://en.wikipedia.org/wiki/Life-cycle_greenhouse_gas_emissions_of_energy_sources https://en.wikipedia.org/wiki/Life-cycle_greenhouse_gas_emis... [2] https://en.wikipedia.org/wiki/Environmental_impact_of_reservoirs#Greenhouse_gases https://en.wikipedia.org/wiki/Environmental_impact_of_reserv...
- sradman 6y agoFlooding land for hydro power generation can also release significant amounts of natural mercury: https://en.wikipedia.org/wiki/James_Bay_Project#Mercury_pollution https://en.wikipedia.org/wiki/James_Bay_Project#Mercury_poll...
- Retric 6y agoMethane’s impact is really overblown. It’s got an atmospheric half life of ~7 years and rapidly turns into CO2. Hydroelectric’s steady state is therefore already baked into the current climate and future releases are equivalent to about ~285 million metric tons of CO2. (The difference is due to CH4 being heavier than CO2.) Except the carbon in that methane comes the atmosphere so the the long term global warming impact of existing dams is approximately zero. Now increasing methane production can have an impact, but it just doesn’t stack linearly like CO2 does.
- soperj 6y agoHow is it overblown sorry? It's half life is actually 9.1 years, which means after nearly a decade, half of it is still left, and this is methane produced annually, so it's continually being added to. Add that to the fact that methane is 84 times better at trapping heat within the atmosphere than C02. Most methane production from Hydro isn't even counted because it's considered green.
- droopyEyelids 6y agoDo you have a link explaining that? Cement is made by baking limestone in a kiln, so the energy inputs are really high. I thought it was up there with smelting.
- sradman 6y agohttps://en.wikipedia.org/wiki/Portland_cement#Environmental_effects https://en.wikipedia.org/wiki/Portland_cement#Environmental_...
- jerven 6y agoThe steel is still steel a hundred years later. Anyway life time co2 is bounded by project cost. E.g. If you bought coal/gas for the cost of the project how much co2 and energy would you produce. Most estimates are about 3 to 6 months to recover energy used to produce a wind turbine.
- vbezhenar 6y agoSteel corrodes and rusts in a salt water. You need to replace steel or replace the entire construction after some time.
- SiempreViernes 6y agoWe've known of paint for a while.
- AstralStorm 6y agoAnd also of galvanic protection with copper electrodes.
- arethuza 6y agoI can remember watching one of the jackets for the Forties field being towed down the Moray Firth in '74. Still there and working today! https://www.energyvoice.com/opinion/92008/forties-at-40-the-ultimate-north-sea-prize/ https://www.energyvoice.com/opinion/92008/forties-at-40-the-... https://en.wikipedia.org/wiki/Forties_Oil_Field https://en.wikipedia.org/wiki/Forties_Oil_Field
- hadlock 6y agoOnce you get about half an inch to three quarters of an inch, the steel creates an oxide layer that protects the material underneath. You can look at ship wrecks all over the world from a hundred years ago, the steel for the steam boiler is usually the last to go. The steel cables holding up the suspension bridge Golden Gate Bridge in San Francisco (87 years old), clouded in fog and arguably one of the harsher saltwater environments (near-constant 20mph winds 8 months out of the year) is still using it's original steel cables, and there are no plans to replace them.
- jarvist 6y agoFrom the brochure, it's 2300 tons of steel in the substructure vs. 670 ton weight of the towers. It's not stated what fraction of the ballast is fixed, and what fraction is water. Normally the fixed ballast would be rock. I don't know how these numbers compare to a shallow water fixed installation, or even an onshore turbine (they must have some foundations!).
- gehsty 6y agoHywind is a demonstration site, I understand it was not optimised not for foundation design, it’s main purpose was to get an understanding of the dynamics of the turbine blades as the structure pitches and rolls, so I wouldn’t focus on the 10,000te figure. Future generations will reduce this significantly.