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I loved this, especially because when I read comments that start with "It's math time", usually they go on to show how some "nice in theory" idea would never scale, but that's the complete opposite in this case!

Also, another thing that's good about these types of energy intensive industrial operations is they can essentially act as a sort of battery - it's a large load on the grid but (I'm guessing, someone correct me if I'm wrong) could potentially be more flexible with respect to time shifting: if it's a bright sunny day, crank up the furnaces to full speed, but if it's cloudy, back off. That helps make solar installations more economical if there is a good chance something will be there to take up extra power.

You're correct that the power required is quite big. It's actually one of the dead-spot in my comment. Supplying 135MWh for 37min is a lot. For example, the Jichuan Solar Park – China is "1,000MWh" and 90km^2 wide (I assume the number is the optimal output).

So, if we want to produce 1,888 millions tons of crude steel with solar panels, and assuming we can supply with Jichuan solar park 10 plants producing 300T of steel:

1,888/3 = 630 steel factory = 630 Jichuan Solar park = 56700km2. It's a bit larger than Croatia. For steel only. And it's assuming ideal production, only solar panel surface...So it could be Ireland actually.

As for the "nice in theory", my small demonstration is actually in this ball park, because the other dead-spot is that I account for electric production. It represent ~30PWh and worldwide consumption of energy is ~180 PWh (85% of those are from fossil).

So this 5% increase of renewable energy, of total electricity production, is actually swimming in those 15%.

Northern Africa has a lot of cheap land and a lot of sun. Wind, too. Steel can be then transported (it is already shipped across large distances). You would have to solve maintenance, but that should be doable.

The main obstacle for investment is political stability and alignment.

There's another catch to your calculation: arc furnaces use scrap steel, which is only enough to supply 30% of the world's demand at this time. That's why 30% of steel is from electrical power. AFAIK most of the furnaces are already built in places with plentiful renewable power to take advantage of negative power prices. There are furnaces in Europe that operate only when the power is free.

Most of the world's steel is produced from ore, which not only requires three times the energy of recycling scrap but also vast quantities of carbon from fossil fuels to incorporate into the alloy. I believe there's a relatively new electrolytic process for the ore but at far smaller scale and it requires even more power.

I love math like this. It makes things sound doable. 144 TWH is a lot of power. The world produces about 25000 TWH per year currently. So, we're talking less than a percent here of global electricity generation. Which over the course of the next decades is going to shift to be mostly/entirely generated by renewables.

This obviously won't happen overnight. But it suggests a few long term trends for steel production to move close to where renewable power is cheapest and most plentiful. E.g. Australia is a renewables power house and exports a lot of mined but unrefined materials. Long term it makes more sense to produce aluminium, steel, etc. locally instead of exporting the ore to China, India, etc. and then re-importing it the upcycled materials.

Thank you. I actually have to point that 25,000 TWh (I have the number of 29 PWh) is electric production only. global energy consumption is ~180,000TWh (a drop of 10,000TWh during covid, yay!), 85% of it is (c)oil&gas.

My numbers might be slightly out of date. It makes sense for energy generation to have grown recently.

For oil and gas energy usage, you should take into account that usable energy and energy consumption are two things. When electrifying, you typically end up needing less energy overall. The notion of replacing oil twh with solar twh is simply wrong. This is something the IEA gets wrong in most of its reports. Which is one reason why their estimates and predictions keep having to be corrected by them every few years.

A good example is ICE cars vs. EVs. A gallon of gas represents about 33.7 kwh of energy. A Tesla can do over 4 miles per kwh. Most ICE cars get nowhere near 120 miles per gallon. Anything over 1 mile per kwh of gas is actually pretty good. Especially for bigger cars. So, an ICE car wastes about 70-80% or more of its energy (heat, noise, vibrations, friction, etc.). You see the same pattern in other sectors where electrifying usually also means improved efficiencies. Most Teslas only have 2-3 gallons worth of kwh in the car. An ICE car with a tank that small would have a terrible range.

So, a doubling or tripling of electricity generation might actually be good enough to replace most fossil fuel usage.

You are correct, but conversion from thermal to electricity is quite inneficient. and it represent 60% of global electricity production. So driving a tesla is more efficient IF it comes from renewable.

EVs (and heat pumps) do not require renewable grids to be more efficient than ICE cars (and gas boilers)

They are sufficiently more efficient (roughly 4x) than even adding the 60% inefficiency of gas turbines and electricity transmission, charging losses etc. do not destroy their inherent efficiency advantage.

That's one of the neat things about heat pumps. In my province in Canada about 25% of our energy is used as electricity and 75% is used as heat. This is ignoring cars, looking at residential, commercial, and industrial. The majority of our electricity generation comes from coal and natural gas, with some hydro and some wind/solar. People are very keen to close down the polluting power plants but are generally quite quiet on the topic of converting our residential and commercial heating to electric even though that covers 75% of our energy use.

But with heat pumps (backed up by resistive heating since we get cold enough to need it), we can still get a win there. Natural gas and coal generation can be ~30% efficient, but heat pumps can readily have a 4:1 COP or better. Even factoring in the inefficient generation of electricity we can still heat our homes with net less energy and then focus on replacing our electricity generation with less polluting sources (eg a mix of nuclear baseload, wind+solar+battery, and natural gas as a fallback)

> 1.44 gigajoules (0.4MWh) is required for 1 ton of steel. In theory.

That's actually a lot less than I thought it would be. My smallish (6kW) solar system on my garage has generated 20MWh in the ~3.5 years it's been operating. I'm sure 50 tons (in theory) of steel isn't huge by industrial standards, but that's more than I'd expect from a residential array in Michigan.

It's a little bit more than the energy of a "normal" lightning, according to wikipedia^T^M

One of the side problem is energy density. Your garage can deliver 6kWh at best, but it can't deliver 12kWh for 30min.

you don't happen to play factorio do you?

I did played to shapez. But I realized it's programming for kids and I'm not a kid anymore ahah, so better programming for usefull things.

The heated metal can act as a battery. Another post on HN says they can recover 40% of energy from a heat source over 1000C. Seems like everyone wins here.

> We observed +5% of renewable energy production worldwide

“The amount of renewable energy capacity added to energy systems around the world grew by 50% in 2023, reaching almost 510 gigawatts (GW), with solar PV accounting for three-quarters of additions worldwide, according to Renewables 2023” https://www.iea.org/news/massive-expansion-of-renewable-powe...

A sector can grow by 50% and still be a small fraction of the overall mix.

This is in fact the common problem with growth figures: going from 0 to 1 unit is literally infinity % growth, going from 1 to 2 at the same rate is 100%, but 1 to 3 is now only 50% etc...

But you've also got the problem that capacity versus production is important to renewable energy in a way which doesn't apply the same to fossil fuels. Build a 1GW thermal power plant, you'll get about 0.8GW across the year. Build a 1GW solar plant, you'll get 0.1 - 0.25 GW across the year. But in terms of capacity you theoretically have 1GW, and at times on any given day, will.

Wind and solar supplied 12% of global electricity in 2022 up from 10% in 2021 and things are still accelerating. You can’t keep this kind of growth rate up for long before things change. https://www.cnbc.com/2023/04/12/wind-and-solar-generated-a-r...

Your capacity factor numbers are also off ex: 29.7% capacity factor averaged over 3 years https://en.wikipedia.org/wiki/Mount_Signal_Solar.

Thermal is also much lower than your suggesting. China the world’s #1 coal consumer has capacity factors under 50% because they are using them for load following. France’s nuclear averaged ~70% for years for similar reasons. It’s only where the there’s excess natural gas and minimal solar/wind that thermal can keep high capacity factors but that’s becoming rare.

Grabbing one specific solar install and saying it's representative of all solar is absurd. If I take my rooftop solar in Sydney and generalize then I'd be saying it's 12.5%.

If I go by the CSIRO estimates[1] then that range is a reasonable middle for Australia (generally considered a sunny country) and would be optimistic for somewhere like Germany[2].

You're also misrepresenting capacity factors for thermal power plants: a thermal powerplant used to follow load operates below it's maximum capacity factor. Renewables can't follow load - capacity factor is the best they can do.

[1] https://www.csiro.au/en/research/technology-space/energy/Gen...

[2] https://en.wikipedia.org/wiki/Solar_power_in_Germany

I’m saying your range was incorrect and it only takes one example to show that. But here’s another 32.3% using single axes tracking: https://en.wikipedia.org/wiki/Mesquite_Solar_project. I can go over 35%, but the point’s clear. In the real world roughly half of grid scale solar power is generated from plants over 25% capacity factors and sub 15% is mostly just outdated solar thermal or very poor locations only in use because of subsidies. https://emp.lbl.gov/pv-capacity-factors

Thermal power plants pay for fuel and therefore real world capacity factors are lower as renewable generation increases. I could point to many coal power plants in the 40-50% range, but that feels pointless.

Anyway, rooftop solar isn’t representative of the grid scale solar because it’s doesn’t use ideal angles for the latitude let alone 1 or 2 axis tracking. It’s also frequently shaded by trees etc. People trying to make money selling at wholesale prices just care more about efficiency than someone offsetting retail electricity rates.

You are still not getting it. If someone says "we installed 1GW of capacity" then what does that mean?

It means you've either got 1GW of dispatchable generation on hand, or some proportionally much smaller amount of non-dispatchable generation on hand.

The number doesn't mean anything without correct context which was the entire point.

But "dispatchable" is key. Choosing to run a thermal powerplant at lower output due to market conditions is different to literally being unable to generate energy.

So talking about "X increase in renewables" doesn't tell you a thing, which was the entire point I was making.

If you build 100GW of solar then in temperate Australian regions it's actually like having 25, in Germany it's like having 10, and in the California desert I guess you maybe get 40. What you don't get, is 100GW on demand. And overnight you get zero.

All of which has a pretty substantial effect on whether "installed capacity" can move the needle on total CO2 emissions because the effect on grid production is much less linear then traditional thermal power plants.

> "we installed 1GW of capacity"

“Wind and solar supplied 12% of global electricity in 2022” that’s the number I am tracking not how many panels they happened to use. Location and other details matter. Plopping down Solar in the UK, Germany, or southeastern Australia is a poor investment. So no I don’t give a fuck about hypothetical GW in dumb locations, it’s also irrelevant to the point I was making.

> can move the needle on total CO2 emissions because the effect on grid production is much less linear then traditional thermal power plants.

Batteries + Solar means is more linear than thermal not less.

Again just track renewables by kWh over the year not simply nameplate capacity if that’s what you want to know. It’s not some secret people actively tack and report it as useful information.

As to the rest of your points, market conditions exist before you install the power plant. Initially the question is wind or solar more useful needs to be addressed. Pick solar and many choices remain.

Install solar with 1 or even 2 axis tracking and you get more hours per day of generation from the same land and panels than fixed installation but higher cost per kWh. Install it X miles west and power comes on a little later each day. Add a battery and you can shift supply within the day. People don’t just plop down panels randomly there’s a huge amount of optimization up front to maximize long term gains.

Thermal on the other hand has fewer levers, shifting the power plants location doesn’t help match the demand curve and there’s no option for cheaper but less reliable output. The economics also completely kill the idea of having batteries to cover the after work spike in demand etc etc. Right now people are trying to decide if they want a power plant that’s only going to provide 45% of hypothetical capacity while still being forced to pay the full construction costs. Net result an absolutely massive increase in how much wind and solar generation is used not just installed each year.

> “The amount of renewable energy capacity added to energy systems around the world grew by 50% in 2023

Literally the quote I was responding to, with a source, before you ran off on this tangent, I presume because you can't read.

You've continually failed basic reading comprehension here.

Look up the user name on that comment before you dig yourself in deeper. The very first sentence of my initial response to you specifically countered that argument, but you just want to keep repeating it as if it was somehow meaningful.

But I hardly care at this point so I’ll leave with a more simple rebuttal:

Grid scale Solar’s global capacity factor has been flat over the last several years. So kW vs kWh only matters at the local level, globally the difference is a rounding error in terms of climate change and it’s going to remain that way for at least a decade.

This logic does apply to fossil fuels because fossil fuel plants cannot compete on cost with renewables when they’re running at full capacity. In terms of actual production, many fossil fuel plants are running at lower than their potential production.

That's the entire point: a proportional increase in renewables isn't a 1:1 reduction in thermals. You don't replace 1GW of thermal plant capacity with 1GW of solar. You replace some fraction of its output, but it still runs overnight, or at times of low production or whatever.

So installed capacity increasing doesn't directly tell you much about the future composition of the grid, particularly in the absence of significant storage or overnight capable sources like wind (which after still variable).

Well, sort of. You’re likely going to use 100% of possible production for wind and solar. That’s much lower than “capacity”, true. But you’re going to use it.

Fossil fuel sources on the other hand are being rapidly downscaled. And if it’s not operationally profitable to run a gas plant at reduced capacity, the plant will have to shut down entirely. This is happening to peaker plants due to battery power coming online.

the economics of gas plants become much, much worse quickly. The cost of energy from a gas plant that’s run a small portion of its planned output is much higher due to the fixed costs.

This should push up the price of off-renewable time power, which will increase the business case for batteries. It’s a bit of a death loop.

Gas will be here for a long time yet but I predict mainstream forecasts are underestimating how quickly the tides will turn to the share of renewables

Meaning it increased from 3.3% to 5% in 2023?

For some reason that I don't understand, the IEA mostly reports the amount of capacity added to energy systems per year and the changes in that amount. So that 50% number isn't the growth rate of solar PV energy capacity, it's the growth rate of the growth rate. OP is talking about the growth rate of the percentage of the system that is solar.

It's the equivalent of if they identified something's velocity and you tried to contradict them by pointing to its acceleration.

Probably because the base is changing fast enough that it’s hard to compare percentages of the total population over time. Geometric growth is kind of hard to follow.

which mean we can produce close to 3000T of steel in a year with renewable. (1,888 millions tons were produced in a year).

The 5% is for all electric sources. I don't look at renewable only but any sources (and coil&gas makes a solid 60% of it).

Every one has a plan until reality strikes. Or as Mike Tyson put so eloquently, “Everyone has a plan until they get punched in the mouth."