Interesting Links for 04-06-2021

[andrewducker]

Cryobattery energy storage plant proposed for Highlands (claimed efficiency between 60% and 70%)

(tags:temperature air storage energy scotland )

Fifteen Years of Radar Reveal Venus's Most Basic Fact

(tags:space radar )

Disgraced Tory who Boris Johnson gave House of Lords seat against official advice donates £500k to party

(tags:corruption bribes Conservatives )

Is there now a final solution to the mystery of Dyatlov Pass?

(tags:russia snow death history )

How feasible would it be to inject you with microchips in your vaccines?

(tags:vaccination processor conspiracy technology ViaDrCross )

A Fart Joke Is Not a Pogrom

(tags:jokes propaganda Israel Jews genocide )

Thirteen on trial over online abuse and death threats to girl who attacked Islam

(tags:Islam abuse law France )

Comments

[armiphlage]

I'm not sure if cryobatteries make economic sense.

Compressing air enough to liquify it requires expensive rotating equipment with hideously expensive lubricants. If you want to minimize energy costs, you have to use multistage compression, which increases your capital costs. We used to do it at our factory to make liquid nitrogen, but then switched to getting it delivered to avoid the hassle.

Making guesses from the cost of delivered liquid nitrogen, it'd be maybe $0.10 per litre to liquify air in bulk, capital and operating costs included.

One litre of liquid air will expand to about a cubic metre at ambient temperature and pressure. If you had it drive a piston or turbine, it'd generate about 10^5 J, or about 0.02 kWh.

That means you'd need to charge $5.00 per kWh to recover the cost of liquifying the air.

I suspect that it'd be better to sell the liquid oxygen and nitrogen than to try converting it back into electricity.

[andrewducker]

Yeah, that's not even slightly economically viable. Thank you for the numbers!

[danieldwilliam]

Five bucks a kWh is about two orders of magnitude more than it needs to be.

[armiphlage]

A linked article indicates how they might make it more feasible - they plan to store the heat generated during the compression phase. But I still don't understand the economics.

https://www.bbc.com/news/business-50140110

Adiabatic compression (where the air gets hotter as it is compressed) is more efficient than isothermal compression (where you cool the air as it is compressed). However, you can't have your storage medium much hotter than ambient, or the costs of your compressor will soar (both in energy usage, and in needing to buy equipment capable of higher pressures). So they'd need to have multi-stage compression, dumping heat via intercoolers. Perhaps they'll be circulating water from a tank at maybe 50 C (~325 K) to cool the air between compression stages? Depending on the temperatures, number of stages, and type of compressor, they might get about ~85% efficiency.

When turning the liquified air to electricity, if they're using a turbine for power generation, they're limited by Carnot efficiency. If we have temperatures of 79 K and 325K (assuming they're using 50C hot water heated by the compressor intercoolers), that's only about ~75% efficient for the power generation phase.

That gives you an overall efficiency of ~60-65% for the cryobattery.

Nickel-iron batteries also have an overall charge-discharge efficiency of 60-65%. NiFe batteries can be made from stacks of commodity metal plates cheaply sliced by a plasma cutter, instead of needing parts to be precision-machined by 3-axis CNC equipment. NiFe batteries have no rotating parts to wear out or need lubrication. NiFe batteries can respond instantly to changes in power demand, instead of taking minutes to respond. Most importantly, NiFe batteries can be stacked in a warehouse unattended, without needing 24/7 supervision by a stationary equipment engineer.

(caveat: it's been a quarter-century since I studied thermodynamics, and it was tied with statistics as my worst subject).

[andrewducker]

My understanding is that Nickel-iron batteries require significant maintenance, are large, and discharge by themselves. I don't think they're going to catch on either.

[armiphlage]

Wow - the cost of lithium ion batteries has been plummeting, and their efficiency and lifespan is going up. It looks like those might soon be the cheapest for grid storage.

[danieldwilliam]

If you are looking at maybe 65% round trip efficiency and that's on a par with a nickel-iron battery then it is not crazy to build some demo plants and see if you can make the costs comparable or up the conversion efficiency or find some useful niche use-case - even if it's unlikely.

But it doesn't sound like a definate winner does it?

[andrewducker]

Certainly worth a try if you can find someone else to pay for it!

[armiphlage]

It seems like a lot of equipment to do something that can be done more simply with existing methods.

There could be lots of more useful things to do with liquified air than just running a turbine. If you had a facility high in chilly windy mountains, next to hot, urban lowlands, you could liquify air cheaply with offpeak power and pipe it to large buildings for cooling, and THEN run the expanding gases through a turbine. You'd need a smaller-diameter pipe than with chilled brine or ammonia cooling systems, and there would be no need for a return pipe.

[danieldwilliam]

Aye - I thought your comment about being able to stack nickel-iron batteries in a warehouse was very telling.

However, it's early days in the finding of practical solutions to the issue of large amounts of intermittent generation on the grid. I'm not sure we understand the problems very well yet so worthwhile trying out a range of different solutions.

There must be a number of places with some chilly uplands near hotter lowlands. What do you reckon the range of the pipes would be? 60 km?

[armiphlage]

It looks like we'd need to both insulate AND pressurize the pipeline to keep it liquid, or have a double-walled vacuum-insulated pipe (like a long Dewar flask), which would be expensive. 60 km is likely technically feasible, but I suspect long-distance pipelines wouldn't be competitive with traditional HVAC systems.

David E. H. Jones did propose once in New Scientist running a pipeline from the top of Mount Kenya to downtown Nairobi to provide cooling and fresh water. The working fluid would also absorb moisture from the atmosphere on the mountaintop; at the bottom, the pressure would force the water out through a reverse osmosis filter. He proposed treacle as the working fluid, so I am not too sure of how practical it would be.

[danieldwilliam]

60 km seems (from memory) to be the standard maximum distance for shipping heat for district heating schemes but that's an unpressurised pipe - insulated but with acceptable losses of heat from 60C to 45C over the distance travelled, or more as they tend to be shipping waste heat from nuclear power stations or heat intensive industrial processes. The input heat is free so the efficiency of the transfer is not critical.

(Reminds me that I must write something about renewable heat in Scotland soon.)

I do love these slightly Heath Robinson schemes like the Nairobi one.

[armiphlage]

Is 45 C warm enough for direct heating, or is it used as the input to heat pumps?

The one in Toronto uses steam. It's generated just from burning natural gas, not even with cogeneration. Some of the distribution branches don't even have condensate return pipes!.



Some good news - we're expanding our district cooling system! Currently, 80 buildings get cooled in summer using 4 degree C water from the bottom of Lake Ontario. I toured one office tower's basement - the huge compressor bay was empty, replaced with a relatively small heat exchanger sitting quietly in one corner.

https://www.toronto.ca/wp-content/uploads/2021/06/8e43-June-2021-Island-Comm-Assn-mtg-Enwave-DLWC-Update-Final.pdf

[altamira16]

With that last one, I hate these cases. Is this case going to heighten Islamaphobia? How much should people be held accountable for someone else's suicide?

I think there have been a few like it in Massachusetts. Here is one about the suicide of Phoebe Prince.

Here is another one where a woman goaded her boyfriend into suicide. This one was awful.

[andrewducker]

It might do, but that doesn't mean that death threats are okay.

And yeah, it's a thorny area.