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This morning Dave Borlace of YouTube Just Have a Think fame reached out to ask me a few scheme to seize waste warmth from a trash burning electrical energy plant, put it in thermal storage on barges and tow it 28 kilometers downriver to displace gasoline burning boilers in a district heating scheme. It’s all very Rube Goldberg-y, with the identical chemical compounds utilized in hand heaters stuffed in transport containers and a few massive barges a day taking 56-kilometer spherical journeys. However does it pencil out?
The chemical combination, per the corporate’s published, peer-reviewed paper, is sodium acetate trihydrate and water, with a few hint parts added to stop stuff from precipitating out of the liquid and ruining efficiency. Not like hand heaters, it’s reusable hundreds of instances. The stuff is secure sufficient, though you wouldn’t need to drink it or spend any time round bigger concentrations of the polymer. If the barge sank, it wouldn’t be an enormous deal.
The vitality density seems to be 60 Wh/kg (218 kJ/kg) of thermal vitality, so not electrical energy nor anticipated to be, a standard extra of thermal vitality storage answer claims. Given the low temperature of 58° Celsius for the molten liquid, that’s fully ineffective for making electrical energy, so the items are imperfect, however helpful for comparisons. That is mainly molten salt, however a lot decrease temperature than the molten salts utilized in experimental nuclear reactors or dead-end concentrating solar energy crops just like the one which failed just lately in Morocco. That’s good, as a result of when that stuff ‘freezes’ right into a strong, it tends to develop and rupture tanks, in addition to having to be chipped out manually. The excessive temperature variants are additionally very corrosive, which these things appears to keep away from.
As a result of it’s exploiting section change vitality traits — strong to liquid and again with the very excessive vitality necessities of simply the section change — it’s not price heating it a lot above 58° C as a result of the overwhelming majority of the vitality comes from altering section. It’s like water that stays at 0° Celsius for fairly a very long time earlier than altering to ice, and vice versa. It’s the identical thermodynamic get together trick that we use to maintain our iced tea chilly.
The largest Thames barges are 1,650 metric tons in capability, so ignoring the pesky containers, that’s slightly below 100 MWh of low-temperature warmth storage. They’re asserting two barges with 120 MWh between them, in order that pencils out as viable.
A 28 km river journey twice every day for the 2 very massive barges is price exploring for prices and carbon debt. That’s 3-4 hours a method upriver, and 2-3 hours downriver. Upriver would doubtless require a MWh of vitality. Downriver a 3rd of that in all probability. Diesel has an vitality density of 12.6 kWh/kg and tugs are possibly 30% environment friendly, in order that’s about 300 kg of diesel, so virtually a ton of carbon dioxide per spherical journey or two tons a day. (Any errors are mine from Googling for tugboat energy necessities, however it doesn’t seem materials if I’m off a bit.)
That’s a tug and crew making two journeys every means absolutely loaded over eight hours each day. In all probability 4-5 individuals within the crew with a labor price of maybe £60k per particular person annual labor prices. Plus insurance coverage, operational prices of tugs, and so forth. Calling it £1,500 per day in operational prices wouldn’t be out of line.
The sodium acetate trihydride prices round £500 per ton, and 120 MWh would require about 2,000 tons of the stuff. In order that’s a £1 million only for the storage medium. Reusable as much as 10,000 instances they are saying. In idea that’s slightly below 30 years. In all probability one other million for the barges. In observe, let’s amortize it over 20 years. That makes it fairly low cost truly, solely about £300 per day. The warmth seize facility on the supply of warmth may cost a little one other £1.5 million per extrapolation from this study, so one other £200 per day amortized.
So, 120 MWh of low temperature warmth for operational prices of £2,000 or maybe £17 per MWh. Two tons of carbon dioxide or 17 kg per MWh.
In fact, they’re burning waste for vitality to make this warmth and meaning they’re burning plastics. That implies that they’re turning durably sequestered carbon into atmospheric carbon inefficiently. Each ton of municipal strong waste emits over a ton of carbon dioxide. The electrical energy seems to be about 540 grams CO2e/kWh, which is to say it sucks. Additionally, plenty of the waste may very well be recycled and the biomass must be ending up in compost or different biomass utilization schemes.
So transporting the saved warmth isn’t significantly excessive emissions, however making it definitely is. If the warmth had been being captured with 100% effectivity on the waste burning plant, 120 MWh of warmth would equate to maybe 60 MWh of electrical energy. But it surely’s doubtless solely 50% environment friendly, so it’s in all probability one to 1. That 120 MWh of warmth shares the 540 grams CO2e/kWh, so name it 270 for every. Meaning the warmth has a carbon depth of 270 kg per MWh and a day has a carbon depth of over 32 tons of CO2. That’s about 12 million tons of CO2 per 12 months.
Appears a bit Rube Goldberg-y for low temperature warmth. You can simply sink a geothermal shaft and put in an industrial warmth pump that turns electrical energy in warmth very effectively with nobody it. No crew. No diesel. No coping with tides. Decarbonizing electrical energy too.
A floor supply industrial warmth pump with a COP of three (regular for heating, with cooling being larger), would require 40 MWh of electrical energy for a similar warmth each day. At 162 grams CO2e per kWh in London in 2023, that’s about 6.5 tons of CO2 a day or 2.4 million tons per 12 months. That goes down yearly, in fact.
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The 40 MWh per day at London industrial charges would price maybe £4,400 per day. A 2 MW warmth pump (40 MWh/24 hours rounded up) and a little bit of thermal storage to steadiness larger demand intervals may cost a little £2 million as effectively, about the identical as tugs and the warmth storage materials, so £300 or so there. Spherical that to £5,000 per day together with upkeep and the like.
It truly appears to pencil out economically, assuming you may have ‘free’ waste warmth 28 km up river and there’s no price of carbon. And assuming my rapidly Googled supply of operational prices for Thames tugboats make any sense.
However let’s value carbon in for enjoyable. The present UK carbon price is £64.90 per ton of CO2e. The waste warmth plant at 540 grams CO2e per kWh, 0.54 tons per MWh, must be paying £35 per MWh in carbon charges. That turns into maybe one other £2,100 per day for the barges of hand heaters, sharing the fee with the electrical energy. For the warmth pump answer, the carbon value is included within the electrical energy, so it’s not paying that.
How does this web out?
- Barges of hand heaters about £4,100 per day
- Floor supply warmth pump about £5,000 per day
However that’s in 2024. The chances are high that the UK will observe the EU’s emissions buying and selling scheme intently per coverage steering and communications, however it’s not formally linked but, apparently.
EU ETS budgetary guidance for enterprise circumstances kicks in at that time, and once I say kick, it’s going to kick like a mule.
These are USD, so conversion is required. US$203 in 2030 is about £162 per ton. That turns the waste warmth’s share of the generator’s carbon value into £5,200 per day. In 2040 it will likely be £9,300.
Abruptly, that warmth pump is trying higher and higher. The chance that the waste-burning electrical energy producing unit will proceed to be worthwhile with will increase in carbon pricing and plenty of low carbon wind vitality and grid storage hanging round may be very low. I count on that if they really began delivering waste warmth from the plant, it will be a scheme that wouldn’t final a lot past 2030, throwing the entire amortization calculations out the window. If it doesn’t present a strong return on funding by 2030, it by no means will.
Burning municipal trash can’t be decrease carbon. When you bolt on carbon seize, it turns into far more costly. When you pay for the carbon dioxide emissions it turns into far more costly. Because the UK continues to construct large HVDC interconnections to jurisdictions generally hundreds of kilometers away to share North Sea wind with Morocco, European hydro with the UK, and Moroccan sunshine with the UK, the flexibility for a trash-burning plant to compete is disappearing quickly.
My guess is that the trash-burning electrical energy plant will cease working someday between 2030 and 2035, and in consequence, gained’t be producing waste warmth. This is similar outdated story for the district heating facility, so they need to concentrate on this danger. In spite of everything, they solely have gasoline boilers as a result of they needed to change the warmth from the Battersea Energy Station, which shut down in 1983, then lastly is being renovated into blended residential and industrial area with Malaysian traders, with a part of the ability re-opening in 2022.
Absolutely the district heating facility will see the carbon pricing entice and dodge the bullet, and the barges of hand heaters operating laps up and down the Thames will stay an attention-grabbing thought. Or possibly not. It’s not just like the UK has a latest historical past of nice public decisionmaking, particularly the place water is worried.
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