A new way to make steel could cut 5% of CO2 emissions at a stroke
technologyreview.com
technologyreview.com
ISS also is getting a plastic recycling machine that will be used to 3D print replacement parts from plastic waste and old parts.
Human spaceflight is like the Sustainability Olympics.
If anyone is really serious about global warming, shutting down coal plants should be priority 1, natural gas plants priority 2 and transportation emissions priority 3.
In the US using the average electricity mix, an EV like the Model 3 emits a factor of 2.5x less GHG than an equivalent diesel vehicle. Because 40% of electricity is from clean sources (nuclear, wind, hydro, solar, geothermal), and coal is just 27% now.
As for moving transportation to electrical propulsion, the real effect has to be judged by the marginal effect it has on emissions. If the marginal change is covered by coal, the benefit is much smaller than if the marginal change is covered by clean sources.
Citation needed. Hydrolox has the highest Isp, but for a boost stage, that alone at all costs is not the most important quality. Hydrolox engines, tanks and piping all needs to be much larger and heavier than other fuels, and in practice, this eats the gains that the higher Isp buys you and more.
It's not an accident that basically all the new engine designs, by multiple different companies, have tested hydrolox and then switched to methalox.
Additionally: operating oxygen-rich causes the bulk density of hydrolox to improve dramatically. This is relevant for first stages, and if reusable launch vehicles become so cheap that propellant cost becomes a major constraint, then I should point out that liquid oxygen is practically free: less than $100 per ton.
For first stages, you're right (unless you get clever and are able to solve the engineering challenges of running oxygen-rich). For upper stages, hydrolox again looks very attractive (because a first-order optimization shows that it's energetically favorable to use higher Isp on the upper stage than the lower stage if you need to make a choice... of course, commonality of stages is also desirable at lower flight rates).
The opposite is true. The relevant problem of hydrogen is that it readily leaks through thin walls. This means that as methalox rockets move to ever thinner composite tanks made of better materials, hydrolox really cannot do better than the current state of the art.
> operating oxygen-rich causes the bulk density of hydrolox to improve dramatically.
True. But it also makes your exhaust into a hot, oxidizing torch, meaning you need much more durable (and heavier!) engine bells.
> For upper stages, hydrolox again looks very attractive
The other problem is that it must be cooled much deeper, and takes much less energy to boil off, making long term storage a hard problem. This makes hydrolox less interesting for any upper stages/manouvering engines that do anything more complex than deliver cargo to earth orbit. Once you add long coast times, it gets really bad -- to the point that the SLS moon missions actually get lower efficiency from their upper stages than they would get from kerolox, once you account for the extra hydrogen they have to ferry up just to let it boil away.
> commonality of stages is also desirable at lower flight rates
Commonality of stages is desirable at all flight rates. Paying for the highest possible efficiency gadget for every task is one of the reasons old space has such huge problems competing in cost with the new entries. Just having a little more thrust and burning a little more fuel is more cost-efficient than having another engine manufacturing line.
Methalox engines will probably power almost everything newly designed going forward. Not because they are the best solution for anything, but because they are 90% there at everything, while lacking the worst problems of everything. Their fuel is easy to contain and stable for long-term storage, they have no carbon build up in the exhaust, their exhaust is reasonably cool and not heavily corroding, and they have enough thrust and enough of Isp that these advantages will outweigh a minor efficiency loss in almost all situations.
The winds of the industry have shifted, and now that methane has been proven, no new hydrolox engines are being developed, with basically everyone choosing methalox for new designs instead. JSC Kuznetsov, SpaceX, BO, ESA and Landspace all independently made the same choice. Others have chosen to use engines developed by some of them. The end result is that the only major rocket operators still developing a future rocket with non-methalox engines are:
- Roscosmos (The Angara rocket family development was started before methalox was seen as viable. There are future plans for switching propellants, but afaik no funding for them currently.) - Arianespace (The Ariane 6 development was started before methalox was proven. Ariane NEXT is going to run on methane.) - NASA (SLS was mandated to use existing engine designs by the senate, because the senators' home states needed the money.)
Your points about hydrogen leaking are not actually accurate. This doesn't negate the advantages at all, and as vehicles get larger, the advantages become even more pronounced. Oxygen-rich is used on Russian engines, which are some of the best engines ever made (although they haven't improved on them much in the last couple decades).
Commonality of stages is more important at lower flight rates since you have to pay for amortization of the greater development costs.
I like methane/oxygen. It is a very good choice. But I also don't buy into the hydrolox phobia that has become popular. Hydrolox is still a very good choice.
(I think that SpaceX and Blue Origin are completely right for picking methane/oxygen for BFR and New Glenn; I'm speaking even more long-term...)
Random googling gives following two figures to compare:
"A jumbo jet (Boeing 747-400) flying from London to New York burns approximately 70,000 kilograms of fuel"[0]
Falcon 9 Full Thrust - Takeoff mass (tonnes) 549, Payload to LEO (kg) (from Cape Canaveral) 22,800 (expendable)[1]
So, roughly 70 metric tons of fuel for a London->New York flight, vs. 500 metric tons for a LEO launch. It's quite comparable. Now consider that there's five orders of magnitude more flights than there's rocket launches[2]. Even if you take an order of magnitude off that to account for most flights being shorter than LHR->JFK, you still end up with space launches barely registering. And then some rocket fuels are non-carbon-emitting.
--
[0] - https://www.flightdeckfriend.com/ask-a-captain/how-much-fuel...
[1] - https://en.wikipedia.org/wiki/Falcon_9#Performance
[2] - https://garfors.com/2014/06/100000-flights-day-html/ says > 100k flights per day, and there's less than 1 space launch per day.
Space industry definitely isn't emissions-free, but right now it doesn't even register. We might have a problem in the future, but there's hope in switching to cleaner fuels planetside and eventually sourcing fuel for space operations from space. As it is today, in my opinion space industry has very good value proposition in terms of utility/carbon emitted.
The 747’s net cargo of passengers plus luggage probability amounts to around 300-400 lb per passenger. 22,800 / 400 ~= 57 passanger equivalent to 22,800 / 300 ~= 76 passanger equivalents.
Further people take much longer trips than your benchmark getting them even closer.
Maybe less if you're not talking about Americans. Even counting 40lb of luggage those are pretty porky passengers. :)
Clearly no :P Also I realized that, unless I have a specific problem I need to solve, I don't remember or like reading about things. I have been taught things in school/uni that I thought were terribly boring and was bad at, until I needed to solve a problem with that information and then I had to re-learn everything. Kind of a waste of time, but I can't change my brain!
That said, they usually have an even larger CO2 footprint because processes used to make them take natural gas an an input, or use lots of electricity mostly coming from fossil fuels. The main reasons they're chosen are for their specific impulse (hydrogen) or long-term stability and readiness (solid fuel in ICBMs), rather than their CO2 emissions.
If numbers like this were regularly given to laypeople, the climate change discussion situation would be much better. That number for a single flight is ENORMOUS!
Per passenger you are getting something like 50mpg.
Perhaps it's better to restrict oneself to flying OR driving that kind of distance. And it adds up - if you drive: do you ever look at your total mileage, then calculate your carbon emissions?
https://www.nytimes.com/2013/01/27/sunday-review/the-biggest...
"For many people reading this, air travel is their most serious environmental sin. One round-trip flight from New York to Europe or to San Francisco creates a warming effect equivalent to 2 or 3 tons of carbon dioxide per person. The average American generates about 19 tons of carbon dioxide a year; the average European, 10."
Seems like there's some tricky math going on, notice: "equivalent" in the above quote:
http://www.carbonindependent.org/sources_aviation.html
This calculates 180 kg CO2/hour per passenger. So 8 hours or so between NYC and Paris? 1,440 kg. 1.6 tons. Not quite a few orders of magnitude.
Once through all the calculations, the above then states, "The CO2 emissions are therefore rounded up and the Carbon Independent calculator takes a values of 250 kg i.e. ¼ tonne CO2 equivalent per hour flying."
So that's more like 4 tons to Paris. (on Basis 1)
Look at the correction at the bottom of the NYT piece:
> "A news analysis article last Sunday about the impact of air travel on global warming referred imprecisely to the environmental impact of one round-trip flight from New York to Europe or to San Francisco. It has a warming effect equivalent to 2 or 3 tons of carbon dioxide per person, but does not generate that much carbon dioxide per person. (The estimate also includes warming from other greenhouses gases.)"
So actual carbon output per person was correctly calculated, but there is some "carbon equivalent" multiplier slapped on other gasses that brings their totals up from 170kg/px to 2-3T/px.
I personally would not consider that a "enormous" amount of fuel to move 400+ people 5,500km.
These are/were used to power things like lighthouses and radio relays in sparsely populated areas.
nuclear power was not at all pioneered by the space exploration... it was pioneered by people trying to destroy other humans. the first nuclear reactor was not for power electrically, but to breed plutonium for bombs. https://en.wikipedia.org/wiki/Nuclear_power
human spaceflight is a void where intelligence and resources disappear into
Nuclear power was pioneered by people trying to defend their sovereignty.
Human spaceflight will pay dividends in the long run. Short sightedness will never result in profit or improvement.
On the other side, NASA is nowadays quite efficient with their money. And companies like SpaceX showed how costs can be tremendously decreased.
Two for the price of one! (Well, potential solutions to problems that is! One, how to generate oxygen on other planets, and two, how to smelt metals on this one while generating less carbon emissions. Well played!)
(This was sarcasm.)
Until the product is actually built and tested at commercial scale, it’s too early to say how well or affordably it will really work.
Moreover, merely producing a green version of a product for around the same price won’t be enough to transform the industry, given the billions of dollars in sunk costs in steel mills that can operate for decades.
Even if the perfect technology came on the scene today, it’d probably be several decades before we could effectively transition to it
Talk about playing the long game...
I wonder how much cheaper their method would need to be, given the above. Would it be faster/cheaper to develop perfect scrubbers to retrofit onto existing mills? (Funded through donations, and/or to sell to offset carbon taxes.)
Still good to have this new technology available to transition to down the line.
I thought about that over the last few years because it's aqueous process so should be able to run intermittently.
Edit: Paper
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.843...
OTOH, I remember industrial electricity prices to be closer to 7-10cents per kWh, so it won’t be that far off what we have now.
I only know a little about steel prices from being a hobby machinist, but I know a bit more about hay prices. For the price of a cheap laptop, you can get two tons of hay delivered :-)
Hot rolled in US is 928$ per metric ton
Hot rolled in EU is 620$ per metric ton
China is in the mid 500s.
Unclear to me if the new US tariffs are to blame, gap is larger than the 25% I expected.
I could imagine most steel plants are big enough that they'd want their own infrastructure in any case. So, for a future steel plant based on this stuff with its own cheap energy supply, it might end up being cheaper and cleaner. That could end up being really disruptive.
U.S. Steel operates integrated mills, which make steel from raw materials. "Mini-mills" make steel using electric arc blast furnaces to recycle existing steel.
If you need very high quality steel, you have to get it from an integrated mill. Everyone else can use the recycled stuff. The real benefit that you are talking about is the fact that recycled steel quality is improving enough to be useful in more applications.
PS - U.S. Steel is converting their Alabama mill to an electric arc blast furnace (they may have finished by now).
This just isn't true anymore. Process control has improved a lot since EAF mills were first created.
EAF mills also provide more flexibility because they can make much smaller batches. This allows for more niche alloys to become accessible.
This technique looks nearly identical to the technique used to make aluminium from aluminium oxide.
The only difference is it needs to happen much hotter (1500C vs 700C).
The process uses a lot of electricity, so much that it is the main cost of aluminium production.
The process, when used in steelmaking, would use 824.2 kJ/mol of iron(III) oxide, producing 111.6 g/mol of iron. That works out to 7.42 kJ / g, or 2 kwh per kilogram of steel. Price varies widely worldwide, but with the cheapest electricity in europe that works out to about $0.10.[1]
Thats lots of electricity for the refining process, and it seems likley that 0.7kg of coal [2] works out far far cheaper at $0.05 [3].
[1]: https://1-stromvergleich.com/electricity-prices-europe/ [2]: https://www.worldcoal.org/coal/uses-coal/how-steel-produced [3]: https://markets.businessinsider.com/commodities/coal-price
Your estimate of 2kWh per kilo would look very promising for this process. Also the comparison of electrical price, with the price for raw coal surely begs some adjustment.
[1] https://www.quora.com/How-much-energy-does-it-take-to-produc...
[2] https://www.worldsteel.org/en/dam/jcr:f07b864c-908e-4229-9f9...
*Not including the time required to retool the entire Earth's iron smelters into electrolytic smelters and build out associated electric infrastructure needed to accompany the exponential increase of a country's energy intake.
We're talking about a constant factor on top of a steel industry already very dependent on electrical power, certainly not (sigh) an "exponential increase of a country's energy intake".
The coke is the fuel that fires the furnaces.
Look at your iron-carbon phase diagram: https://www.tf.uni-kiel.de/matwis/amat/iss/kap_9/illustr/fe_...
Cast iron contains a high concentration of carbon, which makes it brittle. To make steel you need a heavy oxidizer to extract the (reduced) carbon. This is usually done using a "basic oxygen furnace", which is basically injecting a high pressure, very high velocity stream of oxygen into the metal to game thermodynamics into combusting the carbon without combusting the iron.
The phase diagram is very interesting too. Very little carbon is needed to go from elemental iron to steel, looks like about 0.008%. Thanks for posting that!
The way I understand it, is that when mined they get iron-oxide, Fe(2)O(3), or Fe(3)O(4), so there is no carbon present.
They use the coke to make carbon monoxide (CO). And this process removes the oxide and adds carbon to iron to create pig iron.
From there it will be further processed to create different steels, alloys and iron products.
Wikipedia (https://en.wikipedia.org/wiki/Iron_ore) under the smelting paragraph describes the oxide removal process.
Blast furnaces need fuel to raise the temperature of the blast furnace input to speed up stripping what becomes slag and the oxygen from the iron oxide in the iron ore. Carbon monoxide is what is able to penetrate the iron ore at the high temperatures.
My previous comment is criticizing the author for suggesting that yet another fuel produces the heat for the blast furnace.
BF is very simplistically a giant counter current reactor. Ore and Coke (the reactants) are added at the top at room temperature and hot gas (the "blast") is injected at the bottom and they flow past each other.
CO is not the only reductant that plays a role Hydrogen primarily from the humidity contained within injected gas also plays a role in the heat balance of the furnace.
Hydrogen is actually very efficient at reducing iron and avoids the CO2 byproduct. I know in the past some alternative ironmaking methods have looked into using things like hydrogen gas and natural gas (CH4) to directly reduce iron ore using a process abbreviated as DRI (Direct Reduced Iron) and for a while in the '90's this was marketed as a Blast Furnace alternative I haven't really kept up with technology.
I started my career as a Metallurgist (Materials Engineer) working at a Blast Furnace they are hugely complicated beasts.