Comment by jl6 | Hacker News Reader

Comment by jl6 | Hacker News Reader

The world used about 180,000TWh of energy in 2022[0]. That requires about 21TW of generation capacity. If we assume wind turbines have a capacity factor of about 30% due to the intermittency of wind, we would need about 69TW of nameplate capacity.

If each of these turbines is rated at 16MW, we would need about 4.3 million of them.

Is there enough space?

Let's assume turbines should be spaced 10 rotor diameters apart[2]. A turbine of this size (246m diameter) would need to have about 2.5 * 2.5=6.25km^2 of dedicated space. So we will need about 27 million square kilometers of open sea space.

Coincidentally, that's the same as the total area of continental shelf in the whole world.[3]

Continental shelf depth is up to 200m.[4]

The deepest wind turbines today are in depths of 59m.[5]

What should we conclude? As long as we figure out a way of building turbines in deeper water, or perhaps floating turbines, and a way of manufacturing the required materials (hopefully without recourse to fossil fuels), the project seems just about plausible. But it would be a truly planet-scale endeavour.

[0] https://ourworldindata.org/energy-production-consumption

[1] https://en.wikipedia.org/wiki/Capacity_factor#Wind_farm

[2] https://ideasmedioambientales.com/wind-turbine-spacing/

[3] https://en.wikipedia.org/wiki/Continental_shelf

[4] https://www.britannica.com/science/continental-shelf

[5] https://www.sse.com/news-and-views/2023/04/world-s-deepest-o...*

You're confusing primary energy with useful energy.

What people need to realize is that if we go to renewable, electric energy, in most cases this will also involve efficiency improvements. Many fossil fuel based processes are horribly inefficient, with electricity you can often avoid doing things like "80% of our energy goes into heating up the air around whatever we're doing".

That said: Yes, we'll need a lot of wind turbines.

I don't mind being conservative for this exercise, and renewables have their own inefficiency issue: we'll need to accept the inefficiency of using electrolysis to produce the hydrogen needed to synthesize the feedstocks needed to run petrochemical processes (e.g. producing plastic), because energy production isn't the only thing that depends on fossil fuels.

The goal is to stop turning fossil fuels into CO2. Plastic production is not an urgent issue.

There are however various companies looking to e.g. make ethylene from CO2 which, if made economically viable, simultaneously fixes previous fossil CO2 release, and further reduces the financial viability of continuing to drill for more fossil gasses.

Hydrogen production is about 80% efficient and only a small part of our needs depend of hydrogen.

> of open sea space

I'm not disagreeing with your math, but it doesn't need to be offshore only. Currently 93% of wind power is on land, and 7% is offshore[1].

In the United States, it's much more extreme. Literally 99.99% of turbines are on land and 0.01% are offshore[2].

Offshore is growing faster than onshore, though.

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[1] See "Technology deployment" section here: https://www.iea.org/energy-system/renewables/wind

[2] See this map: https://eerscmap.usgs.gov/uswtdb/viewer/ . It shows 72,731 wind turbines, 7 of which are offshore. Also see this Wikipedia article: https://en.wikipedia.org/wiki/List_of_offshore_wind_farms_in...

Is anyone seriously proposing a wind turbine monoculture for energy generation?

Pick your desired percentage of wind in the future energy mix. Even if we say 25%, it's still going to need millions of turbines. And our energy demands are not shrinking.

My country produces around 20% of its energy from wind nowadays, 2010 it was less than 3%. Seems to work just fine and is growing rapidly.

We built about a million aircraft globally during WWII (specifically: 1939-1945). I’m not saying the average WWII airplane compares perfectly to a modern wind turbine, but the technology and industrial base we used to do this was also vastly more primitive. So yes, I’d bet that a sufficiently-motivated human society can crank out a million turbines over a multi-decade time span. You can Google the IEA “Net Zero by 2050” report to find estimates of how much offshore wind capacity there is (it’s a lot.)

It does illustrate the specific challenge of this energy transition. If a given energy technology isn’t being mass-produced in factories, it’s basically irrelevant given the scale of what we need to do.

> And our energy demands are not shrinking.

I think they should be, but even if they aren’t, there still is the observation that a kWh of electricity often can produce more of what we really want (light, motion, compute power) than a kWh of oil (about the only thing we can efficiently convert that into is heat)

For example, Google tells me

- petrol is about 12 kWh/kg,

- the modern fiat 500 has a 47l gas tank,

- Tesla sells cars with 50kwh batteries.

Yet, that Fiat doesn’t have ten times the rang of the larger Tesla.

Energy consumption is an indicator of living standards. I hope we harness and use much more reliable energy!

Energy consumption is a bad indicator of living standards. Everything that defines my living standard has become much more energy efficient during my lifetime. I have for example more light in my house than I used to and consume about 20% of the energy I used to. My induction stove uses a lot less energy than the wood fired stove my grandma had at her house. My current computer uses about a tenth of the electricity of my computer twenty years ago and does much more. An electric car uses about a third of the energy of a gas car. A heat pump uses about a fourth of the energy of a fossil furnace.

Induction stove. Electric car. Heat pump. Those are indicators of being born in privilege. What about your AC in car and hotel and home?

USA setting off nukes and Britain fire bombing Dresden are examples of energy use which is wasteful and polluting. There are always exceptions to one broad indicator, in this example energy usage.

Technology improvement typically brings more efficient use of resources and less pollution. Energy consumption, as one indicator, tracks with increased GDP and increased standard of living.

Many advanced economies have decoupled energy use from economic growth.

https://ourworldindata.org/energy-gdp-decoupling

USA, and some western Europe, exported dirty manufacturing energy use and pollution outside the borders. Any nation rich or strong enough to export pollution of manufacturing will tend to show the numbers you highlight.

I recommend you read the short linked article before making strong statements.

> It would be wrong to assume that rich countries have only achieved this by offshoring manufacturing overseas – which would simply mean that other countries are consuming this energy on their behalf. Consumption-based energy use – which adjusts for the energy used to produce the goods we import and export – has also plateaued or fallen in many countries. We see this clearly in the chart for Sweden.

My point is that maximizing energy demand in no way leads to improved living conditions.

Can we agree that energy released and used in war fighting is wasteful? In the general view of war fighting "over there". Britain did not improve the living conditions of those in Dresden.

There are designs for floating turbines (but they still need to be anchors to the sea floor). Though I wonder if, on scale, they could be made into a flotilla that would only need a smaller amount of anchors for the whole thing, and also be towed around if needed.

I heard that the total wind power across the whole world is something like 20 times the total power humanity needs. So if we ended up doing this, we'd stealing some 5% of power from the wind, which is quite a lot. This itself could have significant climate consequences.

Solar shouldn't have this problem, instead: the amount of power we receive from the sun is ridiculously larger than what we can ever thing to consume.

I don't believe that number, wind is essentially second hand solar power and insolation is orders of magnitude larger than what we need. Do you have a source?

That’s just a 2100x2100 square. How much ground area does one of these turbines need?

I know that in reality you couldn’t just put them all in one place.

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