4 ms·

"Can be" is pretty critical. Most hydrogen is currently produced from methane (natural gas) via steam reforming. The barriers toward renewable production are

"Can be" is pretty critical. Most hydrogen is currently produced from methane (natural gas) via steam reforming. The barriers toward renewable production are economic, not technological, but at current prices natural gas is a lot cheaper than electrolysis. On the plus side, it's good to know that fertilizer isn't a blocker from going fossil-fuel free.

londons_explore 5y ago
Fertilizer can be carbon free (ammonia from hydrogen from water + sun), but about 0% of the world's supply is that. All the hydrogen comes from natural gas. Steel can be made carbon free, but so far it's all made in a blast furnace with a lot of coal. Aluminium can be carbon free (electricity), but so far we reduce carbon electrodes and release a lot of CO2 because carbon is cheaper than using extra electricity. All it would take is the right global tax or incentive structure and all these industries would quickly move over, saving us 20+% of CO2 emissions!
- sophacles 5y ago
  Sorry for being pedantic, but isn't carbon-free steel just iron?
  - betterunix2 5y ago
    Pretty sure he meant carbon emissions, but technically you are correct, "steel" is a mixture of iron and a relatively small amount of carbon. As far as I know (but I am not an expert) there are not many applications for elemental (pure) iron.
  - bsder 5y ago
    The carbon in the steel is a tiny fraction of the carbon used to make coke which fuels the process. This is similar to plastics. Sure, plastics use petroleum. However, if we quit burning petroleum for cars, suddenly we have 100+ years of petroleum reserves for plastics.
    - sophacles 5y ago
      Oh wow, serious brain-fart on this side. Now that you say it I realize i was kind of being dense - thanks for spelling it out!
- nostrademons 5y ago
  "Steel can be made carbon free, but so far it's all made in a blast furnace with a lot of coal." Most (think I'd heard 75-80%) of it is made in electric arc furnaces from scrap steel these days. This is a big factor in the Rust Belt's decline and Nucor's (and China's) advance: we made enough steel that now we have surplus scrap, and it's cheaper to melt it down and reform it than to dig more iron ore out of the ground and make steel in blast furnaces. I thought aluminum production was also largely in electric arc furnaces, and the main CO2 contribution was generating the electricity used for it. Edit: apparently it's about 70% of steel in the U.S. is produced by electric arc furnaces, and they produce about 85% less CO2 than blast furnaces. Aluminum is produced in electric arc furnaces, but with carbon electrodes, which release about 1/2 lb of CO2 for every pound of aluminum.
  - londons_explore 5y ago
    I'm not counting arc furnaces for steel because they don't make steel - they recycle already made steel. Also, the recycling rate for steel is partly only impressively high because a lot of steel is wasted during the steelmaking process - so it isn't really recycling either, merely a loop inside the manufacturing process.

londons_explore 5y ago

Fertilizer can be carbon free (ammonia from hydrogen from water + sun), but about 0% of the world's supply is that. All the hydrogen comes from natural gas. Steel can be made carbon free, but so far it's all made in a blast furnace with a lot of coal. Aluminium can be carbon free (electricity), but so far we reduce carbon electrodes and release a lot of CO2 because carbon is cheaper than using extra electricity. All it would take is the right global tax or incentive structure and all these industries would quickly move over, saving us 20+% of CO2 emissions!

sophacles 5y ago
Sorry for being pedantic, but isn't carbon-free steel just iron?
- betterunix2 5y ago
  Pretty sure he meant carbon emissions, but technically you are correct, "steel" is a mixture of iron and a relatively small amount of carbon. As far as I know (but I am not an expert) there are not many applications for elemental (pure) iron.
- bsder 5y ago
  The carbon in the steel is a tiny fraction of the carbon used to make coke which fuels the process. This is similar to plastics. Sure, plastics use petroleum. However, if we quit burning petroleum for cars, suddenly we have 100+ years of petroleum reserves for plastics.
  - sophacles 5y ago
    Oh wow, serious brain-fart on this side. Now that you say it I realize i was kind of being dense - thanks for spelling it out!
nostrademons 5y ago
"Steel can be made carbon free, but so far it's all made in a blast furnace with a lot of coal." Most (think I'd heard 75-80%) of it is made in electric arc furnaces from scrap steel these days. This is a big factor in the Rust Belt's decline and Nucor's (and China's) advance: we made enough steel that now we have surplus scrap, and it's cheaper to melt it down and reform it than to dig more iron ore out of the ground and make steel in blast furnaces. I thought aluminum production was also largely in electric arc furnaces, and the main CO2 contribution was generating the electricity used for it. Edit: apparently it's about 70% of steel in the U.S. is produced by electric arc furnaces, and they produce about 85% less CO2 than blast furnaces. Aluminum is produced in electric arc furnaces, but with carbon electrodes, which release about 1/2 lb of CO2 for every pound of aluminum.
- londons_explore 5y ago
  I'm not counting arc furnaces for steel because they don't make steel - they recycle already made steel. Also, the recycling rate for steel is partly only impressively high because a lot of steel is wasted during the steelmaking process - so it isn't really recycling either, merely a loop inside the manufacturing process.