We just need more hills
August 7, 2021 12:57 PM   Subscribe

Mining the lime and marl requires energy, though. That’s where the energy to fuel the truck is coming from.
posted by mr_roboto at 1:12 PM on August 7, 2021 [2 favorites]

Sure, but that energy would be wasted otherwise - this recaptures some of it, at least.
posted by sagc at 1:17 PM on August 7, 2021 [4 favorites]

Isn't the energy coming from whatever geological process made/moved the rock above sea level? I mean, yes obviously you have to expend energy to make the rocks movable, but that's not where their potential energy is ultimately from.
posted by Jon Mitchell at 1:17 PM on August 7, 2021 [10 favorites]

That’s pretty cool.
Does the several-times-a-day recharging wear the battery out significantly faster?
posted by Thorzdad at 1:24 PM on August 7, 2021

An even more energy efficient way to use the stored geomorphological potential energy. (Also a mine.)
posted by clew at 1:31 PM on August 7, 2021 [2 favorites]

The UKs last aerial ropeway uses no power, moves 300 tonnes a day, and will be gone by 2036. - YouTube.

That potential energy comes in handy. If the truck works as a positive energy gain, maybe it powers some of the extraction, or at least the workers cell phones.

posted by zengargoyle at 1:33 PM on August 7, 2021 [5 favorites]

That’s where the energy to fuel the truck is coming from.

Darned science people, spoil all the good magic tricks.... ;-) :-} ,-)
posted by sammyo at 1:36 PM on August 7, 2021

That saves up to 196 metric tons of global-warming carbon-dioxide gas a year.
If I've got the math right, that's enough C02 to offset the production of 100 truckloads of concrete per year.

(Also can't help but notice the truck is painted green.)posted by joeyh at 1:42 PM on August 7, 2021 [7 favorites]

The article also links to this experiment with a Chevy Bolt in the Rockies, where the descent recharged a decent fraction of the battery. Maybe I need to take my Bolt up Mt Tamalpais to test it out, in the name of science, of course ...
posted by chbrooks at 1:48 PM on August 7, 2021 [4 favorites]

Interesting spin on the age-old notion of moving mountains.
posted by riverlife at 1:50 PM on August 7, 2021

Please don’t spoil the illusion of an over unity dump truck.
posted by interogative mood at 1:56 PM on August 7, 2021 [1 favorite]

That saves up to 196 metric tons of global-warming carbon-dioxide gas a year.

Please to pay no attention to the cement being made.
posted by They sucked his brains out! at 2:02 PM on August 7, 2021 [5 favorites]

The energy comes from the decision to process the material downhill from the mine.
posted by achrise at 2:33 PM on August 7, 2021 [1 favorite]

Surely it will be used downhill from the mine after processing - so in this ideal frictionless world it doesn't really matter much where the processing is done.
posted by each day we work at 2:39 PM on August 7, 2021

All we need to do is build EVs on the moon and have them charge up on their way down to the planet (waves hands), then even with some lossage from inefficiency they should go a good long time without recharging.
posted by zengargoyle at 2:42 PM on August 7, 2021

Okay, but hear me out. Our parents had to walk to school, 20 miles, uphill both ways.

So if we only drove EVs backwards along that route...
posted by allegedly at 2:45 PM on August 7, 2021 [12 favorites]

(waves hands)
A Mach 32 capable windmill would do it nicely.
posted by rhamphorhynchus at 3:20 PM on August 7, 2021 [1 favorite]

There is a certain Type of Guy who is going to read this article and decide to start loading his Tesla with rocks whenever he's at a topological high point.
posted by qxntpqbbbqxl at 3:21 PM on August 7, 2021 [2 favorites]

Start EV ride share service that only goes from the top of the mountain to the bottom.
posted by zengargoyle at 3:26 PM on August 7, 2021

Plans approved for a Gravity Battery near Pahrump Nevada involves electric train cars going up the mountain at night then powering the grid during peak use during day as they decend down the slope.
posted by hortense at 3:27 PM on August 7, 2021 [3 favorites]

There is a certain Type of Guy who is going to read this article and decide to start loading his Tesla with rocks whenever he's at a topological high point.

Business model: what if Uber, but rocks?
posted by jquinby at 3:30 PM on August 7, 2021 [4 favorites]

start loading his Tesla with rocks whenever he's at a topological high point

Eventually, with the paired unloading of the rocks at the route low point, this will level out all our roads, making them suitable for rail. All right then!
posted by clew at 3:42 PM on August 7, 2021 [6 favorites]

Yeah until we fix the fact that there are billions of humans on the planet nothing else is worth fixing.

Or we could resist the impulse to shit on improvements to something problematic like mining.
posted by tigrrrlily at 4:45 PM on August 7, 2021 [1 favorite]

And when the material you are moving is at a low altitude (like in a gold or copper mine) and needs to go up, you do this.
posted by eye of newt at 6:02 PM on August 7, 2021 [1 favorite]

Gravity battery and mining industry question:
One modern method of mineral extraction, especially things like Appalachian coal, is Mountaintop Removal. (Instead of digging a tunnel into the side of a mountain, you blow the entire top off, scooping it out of the crater like a soft boiled egg in the shell.)
One experimental solution to storing the fluctuating output of clean energy sources like solar and wind is to pump a lot of water to a high place, then let it flow back down later; capturing that as gravity fed hydroelectric power when it's needed later.
Could one combine the two, converting defunct mountaintop mines into reservoirs?
Making up for some of the environmental destruction, stabilizing the power grid, and bringing in jobs in a restorative industry?
(Gonna be losing some of the energy to removing heavy metals from the water as you go.)
*Slaps mountainside* This baby can store 500 megawatts, easy. Sometimes a big rainstorm will give us an extra 25 for free.
posted by bartleby at 6:32 PM on August 7, 2021

Big picture: how much of an impact does zero-energy transport of cement production input make? What else could we do that might have a bigger impact?

This truck is part of an industrial process of cement production, which is the key ingredient in concrete production. On the demand side, there are billions of homo sapiens, who demand shelter from the environment and services such as healthcare, education, transport, much of which is achieved through stuff built out of concrete. Here's a Guardian [1] article introducing concrete and it's greenhouse gas impact:
After water, concrete is the most widely used substance on Earth. If the cement industry were a country, it would be the third largest carbon dioxide emitter in the world with up to 2.8bn tonnes, surpassed only by China and the US. The material is the foundation of modern development, putting roofs over the heads of billions, fortifying our defences against natural disaster and providing a structure for healthcare, education, transport, energy and industry.
Beyond Zero Emissions [2] give one estimate of cement production's greenhouse gas impact:
Cement production is the world’s single biggest industrial cause of carbon pollution, responsible for 8% of global emissions. That’s as much as the global car fleet. [...]The manufacture of one tonne of cement causes about 0.87 tonnes of carbon dioxide emissions (global average). More than half (55%) of the emissions from cement making are a result of heating limestone. [...] A further 32% of cement-related emissions come from burning fossil fuels (coal, coke or natural gas) to generate the heat required to make clinker in the rotary kiln. The remaining 13% of emissions relate to the electricity used to grind and transport material.
The most common type of cement used worldwide (~95%) is portland cement. Portland cement is about 90% clinker by mass, and 10% other stuff. A 2009 Ecofys report for EU [3] calls out the key importance of clinker production:
One of the most important indicators to measure the efficiency of a cement plant is the specific energy consumption for the production of clinker (in MJ/t clinker).
The Ecofys report lists average sources of CO_2 during clinker production: calcination: 55% , thermal energy required for calcination: 22% , heat losses: 13% , transportation: 5%, electricity: 5% . Both the BZE and Ecofys estimates suggest a zero-energy ore transporter might reduce the carbon dioxide emissions of cement production by at most roughly 5% . From the Ecofys study we see that if we somehow improved the process to eliminate all CO_2 emissions due to heat losses, thermal energy, transport and electricity, we could lower the CO_2 emissions of clinker production from 100% down to 55% due to calcination.

A 2017 UN report on eco-efficient cement [4] explains the importance of the calcination process:
From the standpoint of CO2 emissions, the most important characteristic of [minerals used in Portland cement] is the calcium content. The calcium comes from calcium carbonate (limestone) and the first step of producing clinker is the decarbonation of the limestone:

CaCO3 → CaO + CO2

This is the chemical reaction that accounts for some 60% of CO2 emissions from the manufacture of traditional Portland cement. Since no large-volume concentrated sources of calcium exist other than limestone, the manufacture of calcium-based cements inevitably leads to substantial “chemical” CO2 emissions associated solely with the decarbonation reaction, and not with the fuel burned in the process. It is exactly for this reason that the cement industry is such a significant CO2 emitter. This also a cause for optimism — it is clearly possible to reduce these emissions in a relatively inexpensive way, simply by changing the composition of cements.
One ton of portland cement requires about 0.54 tons of input CaO and 0.46 tons of other inputs. The CaO comes from CaCO3 in limestone. After we cook limestone to decarbonise it, limestone's composition, by mass, is around 55% CaO, 43% CO_2 and 2% other stuff [5]. So producing 1 ton of portland cement needs CaO from about 1 ton of limestone, and getting the CaO out of limestone by cooking it chemically releases 0.43 tons of CO_2 emissions.

How to reduce greenhouse gas emissions related to concrete production?

1. I reckon the biggest thing we could do is to focus on demand side: reduce demand. Difficult politically to discuss reducing or regulating the human population. Pretty difficult politically to discuss reducing demand for housing, schools, hospitals, etc. Anonymous online forums are not a productive place to debate one-child policies & so on.
2. replace use of concrete as a building material with a lower-emission material. Wood?
3. replace use of portland cement in concrete with lower-emission alternatives. Some of the various reports linked below argue for this. E.g. Geopolymer cement (BZE 2017), cements with reduced clinker content (UN 2017).
4. keep using portland cement but make incremental reductions in emissions by decarbonising energy supply, reducing heat lost.

Another thing that would be very helpful would be pricing the externality of CO_2 into the world economy, aka carbon tax. Apparently the bulk price portland cement in 2020 was about USD $124 / metric ton. To a first approximation, we've seen manufacturing one ton of portland cement produces one ton of CO_2 pollution. If we assumed a low-end carbon price of USD $25 per emitted ton of CO_2, that would effectively raise the price of portland cement to USD $149 / ton. For a more serious "we're not mucking around" carbon price of USD $250 per emitted ton of CO_2 , that'd translate to a price of portland cement of $374 / ton. That'd give capitalist entrepreneurial industrialists a big profit incentive to deploy alternative cement products with satisfactory material properties but less greenhouse gas emissions in order to win market share from more expensive polluting portland cement.

[1] (Guardian 2019) https://www.theguardian.com/cities/2019/feb/25/concrete-the-most-destructive-material-on-earth
[2] (BZE 2017) https://bze.org.au/research_release/rethinking-cement/
[3] (Ecofys 2009 report for EU): https://ec.europa.eu/clima/sites/clima/files/ets/allowances/docs/bm_study-cement_en.pdf
[4] (UN 2017) https://wedocs.unep.org/bitstream/handle/20.500.11822/25281/eco_efficient_cements.pdf
[5] See chapter 5: "Characterisation of limestone and lime" of ??? http://www.ltv.ovgu.de/ltv_media/Downloads/Lehre/Vorlesungen/Process+Engineering+of+Metals+and+Ceramics/Chapter+5+Characterisation+of+limestone+and+lime.pdf

(some of the above may be quite wrong: i am not a chemical process engineer, i am not your chemical process engineer, i drank too much coffee this morning & went down the rabbit hole trying to understand cement manufacturing)
posted by are-coral-made at 7:28 PM on August 7, 2021 [3 favorites]


> One experimental solution to storing the fluctuating output of clean energy sources like solar and wind is to pump a lot of water to a high place, then let it flow back down later; capturing that as gravity fed hydroelectric power when it's needed later. Could one combine the two, converting defunct mountaintop mines into reservoirs?

There's at least one research group scanning global GIS data to identify candidate sites for pumped hydro energy storage: Global pumped hydro atlas . Mine sites as called out as tricky to estimate for suitability as storage from GIS data as:

> Brownfield sites (existing reservoirs, mine sites) are poorly handled at present due to lack of information about their true shapes (and hence volumes).
posted by are-coral-made at 7:47 PM on August 7, 2021 [1 favorite]

Ask me about my plan to use California wildfires to power steam turbines...
posted by ChurchHatesTucker at 7:48 PM on August 7, 2021

Not a mine, but a really simple and efficient battery system: haul a bunch of trains carrying concrete slabs up a hill and let them down to get energy. Would be perfect for empty land.
posted by zardoz at 8:48 PM on August 7, 2021 [2 favorites]

It's a step in the right direction for sure. These are relatively small mine trucks tho' and I'm pretty sure battery tech has not got to the stage of heavy mine trucks ~325tonnes laden (Catepillar jpg) - typical sites I work on. It may get there but there but not yet. Overhead / conveyor systems are fine and well as long as site layout is not changing; many pit mine' layouts change at least monthly as pits widen, are backfilled, and the reinstatement surface is constructed - this necessitates self-powered vehicles on pit sites.

Some progress though[ABB pdf link], it's likely mines will be electrified in a staged process as there are a number of hurdles, mines also often occur in very hot/cold places which can challenge battery storage> Also mines often very remote so where does the power come from? If it's burning coal/oil locally to make electricity that is self-defeating.

A serious issue in NZ is our energy source mix which is 40% renewable (mostly hydro, and mostly in response to early 70's oil shock, and nuclear war threats). The rest is some of the poorest quality coal in the world - we're just closing our only oil refinery down as the government has lost their collective mind. Droughts, one and two year B are becoming a lot more common and the hydro lakes are not refilling fast enough. Meanwhile car electrification is ramping up rapidly. As a result NZ IS importing a lot of coal [RNZ article], not a good look.

But most of our society is designed around several things that needs to stop. Like demolishing buildings rather than remodeling. Absolutely need to move away from cement ETH.ch is working on that. And planning and thinking a lot more before doing, which is hard in industries that are male-led and doing and performative performance is seen as masculine, and thinking about things first as... less masculine

are-coral-made also on taxing shipping fuel, amazing that Maersk is calling for it! But governments need to do this globally. It would also cut out the moving of very low value products like plastics toys, sand and milk powder.

Your point 2 - look up Philip Oldfield@SustainableTall and their page @ unsw
posted by unearthed at 9:31 PM on August 7, 2021 [3 favorites]

In terms of the TOTAL amount of potential energy you can store, it's hard to beat pumped hydro.

Snowy Hydro 2.0 is one such project that simply utilizes existing dams, and is expected to be able to store 350,000 MWh of energy.

But it's unclear if that's what you really need.

You judge a battery on two things - its output, and how much it can store.

Comparing pumped hydro to the Tesla Mega Battery in South Australia.

Tesla Battery (at its actual cost of $A90 million, 100MW output, 129MwH of storage)) - A$900 per kW of output, and A$700 per kWh of storage.

Snowy Hydro (forecast of A$7 billion, but say, overruns to A$10 billion, 2000MW output, 350,000 MWh of storage) - A$5000 per kW of output, and A$30 per kWh of storage.

The question is, what's the use case? Sure, storage is cheap but... do you really NEED to store 3 weeks of energy for the entire state and assume that literally your entire renewable grid goes dark for 3 weeks, with zero wind and solar output?

At this point, it would be much cheaper to simply over-build renewables (wind / solar) as they are getting so cheap and build small battery storage sites and have enough storage to average out consumption over a few days.
posted by xdvesper at 12:51 AM on August 8, 2021 [3 favorites]

There are talks about "mobile recharging" EVs Knight-Rider style...

Imagine big rigs with a hard-docking tow mechanism in the back, that an EV can latch onto, and be recharged by its own regen mechanism as it was "towed" down the road.
posted by kschang at 3:33 PM on August 8, 2021

Perhaps future hitchhikers will congregate on hilltops in hopes of competing to sell off their varying kinetic potential.
posted by CynicalKnight at 8:38 PM on August 8, 2021

Somewhat related, if you run down the batteries in your Tesla somewhere really inconvenient, you can charge it by towing, activating the regen brakes like the dump truck in the FPP.
posted by Harald74 at 11:05 PM on August 8, 2021

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