[gersh]

There are about 37 billion tons of CO2 emissions per year. If you could get the price down to $100/ton, you can get the world net zero for $3.7t/year. US GDP is 25 trillion/year. World GPD is about 96.5 trillion. So, it would cost about 3.8% of world GDP per year. World global military is about $2.2t/year, so it would be higher than global military expenditure, but somewhat theoretically possible. If you substantially reduced emissions, it might be feasible to use carbon capture for the rest.

[alexey-salmin]

> If you could get the price down to $100/ton

That is the price of a ton of coal. Buy it from China BEFORE it gets burned and you have a sensible strategy.

Sucking it back from the atmosphere AFTER burning takes 10x more energy which is complete insanity. "Getting price down" and "when it scales" is an utter misunderstanding of the situation. Scale doesn't defeat the laws of physics.

[gersh]

So long as they have coal power plants, and need the electricity unless it get prohibitively expensive, they will just mine more coal. The way to reduce emissions is to replace high-emission infrastructure.

[rayiner]

The political and logistical problems are a far bigger challenge than energy production. Just think of all the concrete that China and India will need to pour in the coming decades and the CO2 emissions of that.

[alexey-salmin]

No. If cheap energy production wasn't a huge challenge we wouldn't have the CO2 challenge either. It is the same challenge essentially. You can say it's "96% the same challenge" if you want to take concrete into equation.

No politics or logistics can change laws of physics. Burning coal with hand and capturing it with the other at 10x the cost just doesn't make sense, neither from the engineering perspective nor from the economical.

[yurishimo]

I saw a graph of that the other day and supposedly concrete was only about 3% of emissions globally.

Even if India and China triple that, we’re still coming out ahead by focusing on the reduction of fossil fuels for power generation, international transport, and heating buildings.

[pietro72ohboy]

Why should anyone stop China and India from making lives better for their people? Seems like the classic American mindset where they get to pour as much concrete as they’d like but when other countries try to do it, they start talking of the environment.

[Dylan16807]

> That is the price of a ton of coal. Buy it from China BEFORE it gets burned

And then that money funds more mines to get coal out of the ground faster.

> Sucking it back from the atmosphere AFTER burning takes 10x more energy which is complete insanity.

Part of the plan needs to be capture at power plants. Another part of the plan needs to be heavy taxes for releasing CO2. If someone needs the convenience for some use case, let them pay the capture price.

[alexey-salmin]

> Part of the plan needs to be capture at power plants.

You realize that this makes power plants energy-negative?

[Dylan16807]

No it doesn't. You're not turning it back into fuel. You need to bottle it up or react it into a non-gas, both of which use much less energy than you get from combustion.

[alexey-salmin]

Well try to write down a concrete chemical reaction to achieve this and you will be disappointed. Light atoms like carbon don't like to stay close to each other at room temperature. You need to pour a lot of energy into chemical bonds between them to make that happen.

So no, it's still an energy-bound problem and we still burn coal to get energy.

[Dylan16807]

One of the options is just injecting CO2 into very deep caves/water. And it will then react with many rocks all by itself!

The company that Microsoft is buying capture from is using lots of energy to remove CO2 from rocks, but that's because they're working to pull more CO2 from normal air. When you have an exhaust pipe it's already concentrated and you can separate it out much more easily.

[AnthonyMouse]

I'm consistently hearing two claims here. One is that we'll have energy to do carbon capture because we may need to overbuild renewables by 3-5x to account for intermittency and then most of the time we'll have a lot of surplus power, and the other is that the only solution is for people to drastically reduce energy consumption.

Clearly at least one of these is wrong, because we can't simultaneously have a big surplus and have to reduce consumption, so which one is it?

[strken]

Why can't we have an energy surplus and also need to reduce consumption of carbon-intensive goods? It's not clear to me why they'd be mutually exclusive.

If e.g. smelters still need to use coal, then an energy surplus doesn't help them. If carbon capture is expensive even with virtually free power due to wages and infrastructure, the capture cost was reflected in the price of steel, and demand for steel is elastic, then we'd both capture more carbon and reduce steel consumption.

[AnthonyMouse]

> Why can't we have an energy surplus and also need to reduce consumption of carbon-intensive goods? It's not clear to me why they'd be mutually exclusive.

The vast majority of carbon-intensive goods are related to energy production. Even when people talk about things like transportation and agriculture and construction, a major proportion of their CO2 emissions are from burning fuel.

> If e.g. smelters still need to use coal, then an energy surplus doesn't help them.

Smelters are using coal for heat. Burning it directly on site is more efficient than burning it in a power plant, losing most of the heat to conversion inefficiency, losing some of the electricity to distribution and then turning what's left back into heat.

If you had cheap electricity that didn't come from burning coal they could just use electric heat. At which point there would be no need to reduce steel consumption.

[hakfoo]

Part of it is the time dimension.

Electricity infrastructure used to be defined by the factories that run from (say) 9AM to 5PM. The grid has to be sized mostly for their needs, and baseload power (fossil, atomic, hydro) are sized for it, This is slow and costly to spin up and down. You see this reflected in things like utility "time of use" plans, where they offer you dirt-cheap energy at 2AM if you're willing to pay a penalty at 3PM. They'd love for you to sop up the glut by running a Bitcoin miner or chilling your house to 15C overnight.

Renewables move on a dime by comparison. If we need n GW of power at the peak time of 5PM, depending on the yield factors of local solar/wind/tidal/etc, we may end up with an infrastructure that generates 3n or 5n at other times of day. A lot of thinking has gone to batteries/molten salt/pumped hydro as ways we can store that surplus for later needs, but we can also direct the glut into processes that are energy-intensive and only economically viable in a power-too-cheap-to-meter scenario.

The CO2 scrubbers could be a viable sink for that excess power once we've got enough grid-scale storage.

[AnthonyMouse]

You're just making the "we're going to have an energy surplus" case.

We already have storage technologies that could compete with present-day energy prices if charging them was near-free. They're currently not competitive because it isn't, but in your scenario during off-peak it would be. So why would anybody have to reduce consumption then? Buy a battery, charge it when power is dirt cheap and use as much as you do now for no more than you pay now.

[AnthonyMouse]

Isn't the cost of that plus the cost of operating the fossil fuel emitting infrastructure significantly higher than the cost of other known alternative power generation methods?