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Comment by newyankee | Hacker News Reader

The thing is LFP or Sodium ion are both expected to have 5000+ useful cycles soon (or possibly even in production now). This means even if you use one full discharge overnight , this is like 15+ years of life of the battery, although I suspect calendar degradation will be much faster.

Higher the cycle life, lower the levelised cost of storage and this is what matters in my opinion. Best is to have some type of long term storage like a Diesel generator only for estimated 1-2 weeks of the year depending on location where it will be needed.

I feel V2G with 3 days backup and a house low power mode which can be utilised in emergencies might solve even this issue.

Oversizing solar to the extent possible for winter loads is also ideal because so far that does not seem to be the driving cost.

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> Best is to have some type of long term storage like a Diesel generator only for estimated 1-2 weeks of the year depending on location where it will be needed.

Unless you live in a location without much sunlight, it’s better to invest in a solar powered system with a transfer switch to go off grid.

If you size the system appropriately it can recharge the battery by day during an outage and now you can operate off-grid for a very long time.

Diesel generators come with maintenance overhead that adds up year over year. They also contribute nothing during normal times, as opposed to a solar install which can offset electricity costs or even earn money.

If you live somewhere dark this is less helpful, though.

Consumption also matters. Some people have eye-popping amounts of electricity consumption while other households get by with far less. The difference, including heating and cooling costs, is surprisingly large between the highest and lowest households.

>Diesel generators come with maintenance overhead that adds up year over year.

A good diesel generator is going to need very little maintenance operating few hundred hours per year.

Why do people talk about engines like they are unreliable? They are modern marvels.

I just replaced a residential condo building's fossil gas generator (Kohler 48RCLC), at a cost of ~$24k, because the association didn't perform the required maintenance on it. Yes, fossil generators can be reliable if you do the maintenance and you monitor to ensure they are doing a test run weekly/monthly under load. Lots of people don't.

My Powerwall quietly sits there charged and waiting to be under load, and charges to full when storm mode is activated (or I activate it manually). It has a 10 year warranty, 15 years if part of a virtual power plant (which my storage participates in with the local utility). It requires no maintenance. I also received a 30% federal tax credit for the Powerwall, which the building will not receive for a generator.

Diesel is not the same as a gas generator. There are a lot of things to go wrong with gas engines tbh. Diesel on the other hand will mostly run without too much fuss so long as there is compression and there is fuel.

Diesel lasts longer, but you should also be polishing the diesel fuel to keep it in good condition, which is another point of failure. When fossil gas is available, it is usually elected as the fuel of choice because this is unnecessary (as the generator is hooked up to gas pipelines, and no storage consideration is required). Propane will last forever in a proper container, but poses more storage risk than diesel.

TLDR Diesel generators where you might be without mains for a while and intend to replenish the fuel with deliveries during the outage, fossil gas for use cases where gas delivery pipelines are available (urban, suburban), propane for offgrid use cases (rural, cell towers, etc) where fuel longevity is a concern.

https://en.wikipedia.org/wiki/Fuel_polishing

if you dont have an ICE car, i think id prefer propane over gas? ill likely have the propane tank for a grill anyways

I think he is talking about natural gas rather than gasoline/petrol.

In this context, "gas" is "natural gas" delivered continuously through pipelines directly to your property. Propane is delivered by truck periodically, and stored in tanks on your property. Gasoline and diesel would also be delivered by truck periodically.

They are modern marvels indeed, but if you were to park your car in a field in May, by New Years when you go to start it up, it's a coin-flip whether or not it will.

Generators need to be exercised and maintained. You are committing to fire that thing up for a few hours every month, just to make sure it's in running order when you need it (I used to work next to a hospital that fired them every week).

For a modern car, If mice don't get into it and you have a battery maintainer, it's close to 100% going to start right up.

That fuel is probably going to be bad by then thanks to the ethanol that's put in it. Diesel is much more stable in that case.

I wonder if anyone has done any modern testing.

I had a 1990s car that started right up with 2015 fuel that sat in its tank for 9 months.

I had a car parked during covid and then remote work that probably consumed 1 tank of gas over the period of 2 years. Other than battery drain it was fine.

> Generators need to be exercised and maintained. You are committing to fire that thing up for a few hours every month, just to make sure it's in running order when you need it (I used to work next to a hospital that fired them every week).

This can easily be automated, Generac will handle testing for residential generators.

We have several large scale full building generators. Our exercise cycles are 15 minutes once a week. Our diesel mechanics fully service the engines every 3 to 6 months depending on size and importance.

Fuel is easy because we have an external tank with a visual gauge that you can read from several feet away. When they added DEF they neglected to add a DEF gauge that's as easy to read. Thank goodness they sell DEF at any old truck stop.

You do need to run it at least once per quarter, though.

> operating few hundred hours per year

Do you really have a few hundred hours of power outage per year?

Around here, the power is so stable that we go multiple years without an outage that lasts longer than a few seconds.

If I installed a generator it wouldn’t a couple hundred hours per year. It wouldn’t run at all for years at a time unless I manually exercised it as yet another maintenance task for my already too long list of things to maintain.

Unless you live in a location without much sunlight, it’s better to invest in a solar powered system with a transfer switch to go off grid

You're sadly describing my situation. Dec sees 6 hours of light, less even, and while the sun does get above the horizon, it doesn't get over the top of the forest.

(The trees have no leaves, but there's still a lot of tree trunks between me and sun.)

Bah.

> Best is to have some type of long term storage like a Diesel generator

LNG or propane would be far superior fuel types for long term standby generators. Periodically exercising a machine that runs on CH4 results in very minimal buildup on internal components. Liquid fuels are much dirtier and can also go bad.

Diesel is used in situations where you can afford all of the crazy maintenance. It's worth the trade off if you can.

The maintenance difference isn't that large. Diesel in a good tank also lasts an extremely long time, unlike gasoline. Diesel engines are more thermally efficient so you get more electricity per unit of fuel burned. The tanks don't need to be under pressure or replaced nearly as often as those for propane either. This is why most hospitals, data centers etc. that aren't near a natural gas line use diesel generators not propane. Natural gas has the benefit that when piped in, you don't need storage at all.

If you have access to ethanol-free fuel, that basically eliminates gasoline "going bad". It's the ethanol that degenerates over time.

I wouldn't say it "eliminates" it. Even without ethanol, gasoline still goes bad far faster than diesel. Gasoline is full of aromatic hydrocarbons that eventually will break down, and after a few years you're left with a brown stinky liquid.

Up until a year ago where I live, Chevron 94 Octane was ethanol free. I had issues with older carbureted engines after leaving gas in them for ~2 years. With E10 I wouldn't dare go that long as it can be so corrosive.

I can fill diesel tanks myself if need be.

I'm going to have a hell of a time with LPG.

There are dual-fuel generators, Ecoflow has a propane+gasoline option [1]. The problem with a pure propane setup is that propane doesn't really want to get gaseous if it's too cold outside - just like your cigarette lighter that you need to warm in your pants pocket before it can actually light a fire.

Diesel plus <any other kind of fuel> isn't available on cheap residential units I'm aware of, particularly as the ignition and fuel injection mechanisms are much more complex than a gasoline/propane mechanism.

[1] https://www.ecoflow.com/us/dual-fuel-smart-generator

No, LFP is 8k-12k cycles, and sodium are expect to be 15k to perhaps 20k cycles. This is reflected in the manufacturer warranties, and many sources. Here's one:

https://www.volts.wtf/p/whats-the-deal-with-sodium-ion-batte...

that makes calendar aging the limiting factor even more. I feel that so many cycles can also aid in smoothing solar & wind (at turbine level) output and increase their utility.

I feel that long term energy storage will be split between thermal and non thermal in interesting ways and the market for them will open up after first level of daily disruption

20,000 daily cycles if 55 years. 10,000 daily cycles is 27 years. The expected usage case for these batteries is near daily usage.

I hadn't really thought about thermal tech in such extreme terms until your comment, but to me it appears to be the tape storage of our times. There will always be a fair amount of infrastructure hidden that almost nobody knows about, but it's going to be dwarfed in active usage by HDDs or SDDs.

The tech advantages really are that big for batters and other solid state energy tech over the moving parts thermal variety. Thermal tech hasn't had an upgrade like LTO-6 (or is it 7 now) and is pretty much at the end of its possible engineered capabilities, but batteries are just barely getting started on what they are capable of.

The article here concludes with one year long cycle, of the 1MW battery.

Not without exception; there's some draw down after dinner even on the charge up sunny months. But a couple kWh against a 1MW pack is not super super notable. If it were cycle count alone degrading battery it'd still be an almost 5000 year battery (before becoming a 0.8MW battery).

As others are pointing out, we have stabilized chemistries even more, so 5k cycles is pretty low at this point.

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