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Electrically conductive bricks can replace fossil fuels in industrial processes

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Re: Electrically conductive bricks can replace fossil fuels in industrial processes

#61

Post by klyrs »

amelius wrote: post #60
klyrs wrote: post #57

Earlier quoted context omitted.

Responding to your question two above: You've probably seen multiple instances of this in your daily experience. A fuse is a thin conductor between thick electrodes. A light bulb is a very fine conductor between thick electrodes, encapsulated in a vacuum bulb. If you use tungsten electrodes, you can easily melt copper in the manner I've described -- that's how TIG welders work. Responding to your question about elect…

True, but something should be there to close the loop on that not-so-thin brick, and that something will get hot. That picture shows only a single brick, not a loop of bricks so something does not add up.

The picture shows glowing hot electrodes; are you being deliberately obtuse?

Re: Electrically conductive bricks can replace fossil fuels in industrial processes

#62

Post by Qwertious »

throwup238 wrote: post #12
mauvehaus wrote: post #10

How does this fit into the wider picture of steelmaking with electric arc furnaces? Those have been around for a good long while; what can this do that an electric arc furnace can't? https://en.wikipedia.org/wiki/Electric_arc_furnace

Pretty much nothing, at least for steel. You still need the carbon to incorporate into the alloy so like arc furnaces, they can only be used with mostly scrap material. That’s why steel makers still use coal. They need the coke.

IIRC steelmakers use roughly 2 parts iron to 1 part coke, which means coke would be 33% of the weight, but steel is only 1% carbon - that's an efficiency of only 3%. Metallurgical coal is used primarily because it burns hot enough to efficiently melt iron.

Re: Electrically conductive bricks can replace fossil fuels in industrial processes

#63

Post by Qwertious »

XorNot wrote: post #7
thinkingkong wrote: post #6

If these systems have enough thermal mass then maybe you could even power them with solar or daily offset cheaper power in another storage mechanism. Between this and the newer co2 reduction technologies in kilns we might be close to finding ways to build combined steel and cement factories that have massively reduced greenhouse gas emissions.

That's just inefficient solar thermal though. If you want to do that you'd be better off using parabolic mirrors to heat regular fire bricks directly. These are unique it seems because they're durable electric heating elements that can hit industrial process temperatures and might be cheaper then alternatives?

Solar thermal requires lots of pipes that you pump molten salt and/or steam through, it's far more expensive than PV. The efficiency doesn't matter as much as the cost, unless you're limited by land to build grid PV on.

There are no moving parts in PV or these bricks, which means they'll have near-zero maintenance costs.

Also I'm pretty sure solar thermal can't heat steel - it relies on steel pipes throughout the entire system.

Re: Electrically conductive bricks can replace fossil fuels in industrial processes

#64

Post by peepeepoopoo73 »

This is incredibly wasteful and will end up being a net-negative for greenhouse gas emissions by crowding out other, more efficient uses of that electricity besides heating things up. One of the first things they teach you in engineering thermodynamics is that electricity is very high quality energy compared to process heat, and that you can do a lot more useful things with electricity such as powering motors or electronics. Electricity generation typically results in lots of waste heat, which you would be far better off recycling into process heat through cogeneration instead of what this article is doing, which is throwing away process heat to convert electricity into even more process heat.

Re: Electrically conductive bricks can replace fossil fuels in industrial processes

#65

Post by upsuper »

peepeepoopoo73 wrote: post #64

This is incredibly wasteful and will end up being a net-negative for greenhouse gas emissions by crowding out other, more efficient uses of that electricity besides heating things up. One of the first things they teach you in engineering thermodynamics is that electricity is very high quality energy compared to process heat, and that you can do a lot more useful things with electricity such as powering motors or elec…

> Electricity generation typically results in lots of waste heat

Typically, but may no longer be true with renewables. I don't think any of solar pv, wind, and hydro generates significant heat in the process of their power generation.

Re: Electrically conductive bricks can replace fossil fuels in industrial processes

#66

Post by throwup238 »

Qwertious wrote: post #62
throwup238 wrote: post #12

Earlier quoted context omitted.

Pretty much nothing, at least for steel. You still need the carbon to incorporate into the alloy so like arc furnaces, they can only be used with mostly scrap material. That’s why steel makers still use coal. They need the coke.

IIRC steelmakers use roughly 2 parts iron to 1 part coke, which means coke would be 33% of the weight, but steel is only 1% carbon - that's an efficiency of only 3%. Metallurgical coal is used primarily because it burns hot enough to efficiently melt iron.

> Metallurgical coal is used primarily because it burns hot enough to efficiently melt iron.

That’s the historical reason, but now it's used because carbon is a reducing agent that binds to oxygen, preventing it from oxidizing the iron back into iron oxide and because the coke is used as a permeable membrane to let the resulting gasses escape.

If it was just a matter of heat, there's any number of cleaner fuels steelmakers could use but they can't because the coal serves an important role in the chemistry of blast furnaces.

Re: Electrically conductive bricks can replace fossil fuels in industrial processes

#67

Post by danans »

s1artibartfast wrote: post #51
danans wrote: post #46

Earlier quoted context omitted.

> IF you just want to go electricity>heat>electricity I think the idea here is to go electricity->heat-storage->heat-usage, using the heat storage to take advantage of cheap renewables that might be otherwise curtailed and to buffer the heat to provide reliability for whatever process it is used for. Almost any form of energy storage other than heat (i.e. batteries, hydrogen, gravity) would be far more expensive in t…

Thanks, I understand better. I'm sure there are some applications for pre-heating to time shift demand, but I do think it is limited.

> I'm sure there are some applications for pre-heating to time shift demand, but I do think it is limited.

Another example of a big application for time-shifted heating is domestic hot water heating with heat pump water heaters (or even resistance water heaters if the electricity is cheap enough). At least one company (https://www.harvest-thermal.com/) is taking this further to also provide space heating by time-shifting heat, again using water as the energy storage technology.

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