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28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

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Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#121

Post by ComputerGuru »

zaroth wrote: post #60
piaste wrote: post #45

Earlier quoted context omitted.

I'm not sure those considerations are applicable. There is no "ecosystem" that depends on the rate of slowdown of Earth's rotation - we do need to leave some rotation to keep flora and fauna alive, but that's a "reservoir" problem, to use the OP's formulation, not an intensity one. As for the addition of energy (heat) to the planet, sure, but there's nothing specific about tidal energy here. All energy sources except…

Also worth noting that trying to extrapolate the effects of current technology at this timescale is pointless. There will be tide changes in human’s technological capabilities long before there could be any reckoning for over-extraction of the Earth’s rotational energy. For example, in our ability to bring mass into orbit. Add a couple orders of magnitude in that capability, and humans can start directly tuning the E…

How much dust would you need to shoot up to affect a statistically significant change in the amount of sunlight getting through?

Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#122

Post by ComputerGuru »

dogtimeimmortal wrote: post #105
LM358 wrote: post #29

Earlier quoted context omitted.

"Tidal Energy Is Not Renewable": https://cs.stanford.edu/people/zjl/pdf/tide.pdf Previous discussion on HN: https://news.ycombinator.com/item?id=37383283

Thanks for this! Something has always bugged me when I hear about big plans for tidal energy. TLDR, the 1000 year estimate is is derived from the geometric series proof(i needed a refresher). Wolfram explains it pretty well: https://mathworld.wolfram.com/GeometricSeries.html ...then i needed a refresher on exponents and logarithms: https://wou.edu/mathcenter/files/2015/09/Exponents-and-Logar... It's good to do the ma…

Population growth is effectively over.

Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#123

Post by SoftTalker »

zaroth wrote: post #60
piaste wrote: post #45

Earlier quoted context omitted.

I'm not sure those considerations are applicable. There is no "ecosystem" that depends on the rate of slowdown of Earth's rotation - we do need to leave some rotation to keep flora and fauna alive, but that's a "reservoir" problem, to use the OP's formulation, not an intensity one. As for the addition of energy (heat) to the planet, sure, but there's nothing specific about tidal energy here. All energy sources except…

Also worth noting that trying to extrapolate the effects of current technology at this timescale is pointless. There will be tide changes in human’s technological capabilities long before there could be any reckoning for over-extraction of the Earth’s rotational energy. For example, in our ability to bring mass into orbit. Add a couple orders of magnitude in that capability, and humans can start directly tuning the E…

> within the next ~50 years

Very optimistic. We haven't even been to the moon again in 50 years.

500 years, maybe.

Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#125

Post by beefman »

For comparison, electricity was sold to the U.S. grid at about $48/MWh in 2023. This is less than any of the cost projections mentioned in the article.

Howabout materials? It says this weighs 28 tons and makes 1.2 MW. That's 21g/W assuming a 100% capacity factor, no balance of plant, and assuming those are short tons. Compare to an iPhone 15, which consumes about 1W per 150g in use. That's a materials intensity multiple (EROI estimate) of ~ 7. An average automobile on an average commute dissipates about 67kW, or 27g/W for a multiple of ~ 1.

Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#126

Post by macNchz »

lelag wrote: post #6
mywacaday wrote: post #4

Earlier quoted context omitted.

I've often thought why not dam a whole estuary or bay and use hydro to collect the energy on the the fall and rise of the tide. I know the environmental impact wouldake it unpalatable but are there any reasons it wouldn't work?

It's been done. Biggest one is Sihwa Lake Tidal Power Station[1] and France had a 240MW tidal plant since the 60s [2]. This type of project has been few and far between and I would guess they might be very costly to build and maintain compared to the harvested energy. [1] https://en.wikipedia.org/wiki/Sihwa_Lake_Tidal_Power_Station [2] https://en.wikipedia.org/wiki/Rance_Tidal_Power_Station

This is interesting–it made me wonder if this had ever been considered on NYC's East River, which is a tidal estuary with strong currents. Turns out there's been a company working on it for a while, with free-moving turbines rather than something that spans the whole thing: https://www.energy.gov/eere/water/articles/tidal-testing-und...

Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#127

Post by rsynnott »

beefman wrote: post #125

For comparison, electricity was sold to the U.S. grid at about $48/MWh in 2023. This is less than any of the cost projections mentioned in the article. Howabout materials? It says this weighs 28 tons and makes 1.2 MW. That's 21g/W assuming a 100% capacity factor, no balance of plant, and assuming those are short tons. Compare to an iPhone 15, which consumes about 1W per 150g in use. That's a materials intensity multi…

That would benefit from various subsidies; from the article it _looks_ like the $54/MWh projected figure is before subsidy.

Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#128

Post by [deleted] »

debok wrote: post #55
tetha wrote: post #14

Since the number 1.2MW didn't mean much to me, modern on-shore wind turbines seem to supply 3-4MW and offshore ones 8 - 12MW. But this seems a lot easier to transport and install compared to cranes and the nightmare of navigating turbine blades on trucks through places. And if these hold up to water and don't cause too many problems for wildlife, there would be a lot less discussions about these "messing up my skylin…

A kettle uses ~1.5KW, a geyser ~2KW, an oven ~5KW, a stove about ~3KW. These are fairly high estimates I got from some quick googling. If you add these all up, and account for some more appliances (HVAC, fridge/freezer etc.), I think it is safe to estimate that a household less than 20KW at peak, even though it is a fairly high estimate. So going backwards from there, 1.2MW = 1200KW and 1200KW / 20KW = 60 households…

[deleted]

Re: 28-ton, 1.2-megawatt tidal kite is now exporting power to the grid

#130

Post by thfuran »

tetha wrote: post #36
out_of_protocol wrote: post #15

Earlier quoted context omitted.

> too many problems for wildlife There were a meta-analysis regarding population of birds in areas with/without wind turbines, found no statistically significant difference (unlike coal, where difference was huge)

Yep. I mostly meant for or rather caused by this kite. I wouldn't expect it intuitively, as it's just a big object in the water, not moving erratically or obstructing anything.

I guess erratic is in the eye of the beholder, but it's certainly moving.
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