6 ms·

It's math time, let's look what wikipedia say about electric arc furnace: - 1.44 gigajoules (0.4MWh) is required for 1 ton of steel. In theory. - 300T of stee

It's math time, let's look what wikipedia say about electric arc furnace: - 1.44 gigajoules (0.4MWh) is required for 1 ton of steel. In theory. - 300T of steel needs 132 MWh, and a "power-on time" (the time that steel is being melted with an arc) of approximately 37 minutes. ---- wikipedia end ----- From https://ourworldindata.org/grapher/electricity-prod-source-stacked https://ourworldindata.org/grapher/electricity-prod-source-s...: total world electricity from renewable was 10,700TWh in 2021. 11,600 TWh in 2023. 1.5 billions (metric) tons of crude steel were produced in 2023. 30% of it by electric power. ------------------------ (A) Let's assume that 20% of those 30% already come from renewable (which is not the case, anyway). 30x20% is 6%. It means 24% of the 1.5 billions tons are looking for renewable. It means 360 millions of tons needs its green energy. It means we need to find 360 millions x 0.4MWh = 144 TWh. If we don't assume (A), we get 152 TWh. It means we need to dedicate ~1.5% of renewable worldwide energy to replace 24% of crude steel "e-production". In theory... We observed +5% of renewable energy production worldwide. If we wanted to make the steel *production* go green (1.5*3.33 = 5%), in theory it could be possible in one year...in theory. Tbh, I expected a more crazy conclusion. I'm quite sure the number is off by more than 10% though. But even if it was off by 100%, it would mean it's possible in 2 years. On a side note: it's useless anyway if those 5% are not coming with a decrease of 5% of coil&gas consumption. Which is not what's happening... Feel free to redo the math, I can make a mistake!

dr_dshiv 2y ago
> 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-power-opens-door-to-achieving-global-tripling-goal-set-at-cop28 https://www.iea.org/news/massive-expansion-of-renewable-powe...
- XorNot 2y ago
  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.
  - Retric 2y ago
    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-record-amount-of-global-power-in-2022.html 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 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.
    - XorNot 2y ago
      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/GenCost https://www.csiro.au/en/research/technology-space/energy/Gen... [2] https://en.wikipedia.org/wiki/Solar_power_in_Germany https://en.wikipedia.org/wiki/Solar_power_in_Germany
      - Retric 2y ago
        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 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 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.
- deleted 2y ago
  [deleted]
- passwordoops 2y ago
  Meaning it increased from 3.3% to 5% in 2023?
- lolinder 2y ago
  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.
  - jncfhnb 2y ago
    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.
- logtempo 2y ago
  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).
cpill 2y ago
you don't happen to play factorio do you?
- logtempo 2y ago
  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.
dukeofdoom 2y ago
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."
jillesvangurp 2y ago
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.
- deleted 2y ago
  [deleted]
- logtempo 2y ago
  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.
  - jillesvangurp 2y ago
    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.
hn_throwaway_99 2y ago
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.
- logtempo 2y ago
  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%.
  - krab 2y ago
    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.
    - Slava_Propanei 2y ago
organsnyder 2y ago
> 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.
- logtempo 2y ago
  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.
silverlake 2y ago
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.

dr_dshiv 2y ago

> 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-power-opens-door-to-achieving-global-tripling-goal-set-at-cop28 https://www.iea.org/news/massive-expansion-of-renewable-powe...

XorNot 2y ago
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.
- Retric 2y ago
  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-record-amount-of-global-power-in-2022.html 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 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.
  - XorNot 2y ago
    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/GenCost https://www.csiro.au/en/research/technology-space/energy/Gen... [2] https://en.wikipedia.org/wiki/Solar_power_in_Germany https://en.wikipedia.org/wiki/Solar_power_in_Germany
    - Retric 2y ago
      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 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 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.
deleted 2y ago
[deleted]
passwordoops 2y ago
Meaning it increased from 3.3% to 5% in 2023?
lolinder 2y ago
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.
- jncfhnb 2y ago
  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.
logtempo 2y ago
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).

cpill 2y ago

you don't happen to play factorio do you?

logtempo 2y ago
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.

dukeofdoom 2y ago

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."

jillesvangurp 2y ago

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.

deleted 2y ago
[deleted]
logtempo 2y ago
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.
- jillesvangurp 2y ago
  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.

hn_throwaway_99 2y ago

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.

logtempo 2y ago
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%.
- krab 2y ago
  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.
  - Slava_Propanei 2y ago

organsnyder 2y ago

> 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.

logtempo 2y ago
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.

silverlake 2y ago

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.