Californians out of electricity cant get gasoline to generators!

[BrianHG]

A little 3 minute reality check...

[notsob]

And there is always a heat pump system for your hot water ( works on ambient heat - obviously better with sunlight )

https://energieaustralia.com.au/thermodynamic-solar-system/

[orion242]

Why isn't it more common to build houses out of more fire resistant materials like brick and steel in high fire risk areas?

or at least ..... https://californiachaparralblog.wordpress.com/2018/12/07/exterior-fire-sprinklers-saved-188-properties-wet-homes-dont-burn/

Wonder how practical this really is.  System needs to be isolated and self contained.  Power source for the pump and water source. That link calls for a 10k gal tank which isn't a small item.  Does the typical CA lot in these areas have enough space for this?

Just trying to get an idea of the water required...

https://www.forestry.umn.edu/sites/forestry.umn.edu/files/cfans_asset_183520.pdf

60gpm?  So your 10k tank is just under 3hrs of runtime.  Better have perfect timing on activating that.  That said some are running these systems for hours prior to a fire to wet everything.  That's a ton of water in an area that doesn't have an massive supply for starters.

Seems pretty costly and the maintenance on these is probably alot more than most homeowners are capable of.

[richard.cs]

Wonder how practical this really is.  System needs to be isolated and self contained.  Power source for the pump and water source. That link calls for a 10k gal tank which isn't a small item.  Does the typical CA lot in these areas have enough space for this?

10k US gallons is about a 10 foot cube, doesn't sound unreasonable for an underground tank to me, not necessarily cheap though. It's used almost never, so trickle-filling it over many months sounds reasonable, and it could be filled with rainwater / greywater. I've not looked at these systems in any detail but I guess there's a diesel pump that needs to sit idle for years at a time and then reliably run when needed, this needs care and maintenance, but it's a well understood problem. Actually piston engines aren't great at this, but in this application independence from external energy is definitely necessary.

At one point I was considering helping a friend build a fire tank of that sort of size on his (UK) farm, the nearest fire hydrant he has is 1/4 mile away the other side of a busy road and when he'd had a fire previously there was a fairly long delay as hoses were set up and problems with limited flow. It never came to anything in the end, it's a lot of effort for something that probably will never happen again. If he lived somewhere with more significant fire risk we'd probably have done it. In this case we weren't thinking of pumps, just a big local store of water the fire brigade could pump from.

Of course a masonry house with a tile roof is likely to fare rather better in terms of surviving falling embers and radiant heat compared to common US construction, although it'll still catch fire eventually if it's in the middle of a burning forest.

[orion242]

10k US gallons is about a 10 foot cube, doesn't sound unreasonable for an underground tank to me, not necessarily cheap though.

Indeed.  Looking at the tanks, this isn't as big as I initially thought.

@60gpm, that tank isn't lasting very long.  Certainly won't be running the system for hours prior if a fire is in the area to soak things.  Maintenance on the pumps is a hassle most will forget.  Areas with freezing conditions, another hassle.  More fire retardant / proof materials seems like a better investment IMO.  Or maybe just don't build in a natural fire pit in the first place.

[Marco]

The link says radiant heat won't ignite a house from more than 10 meter away ... put an alumized fireproof tarp across the home and that would probably be reduced to a couple of meters.

Maybe you could make a system with two pyrotechnic launchers on the outer edges of a roll of tarp to quickly shoot it across a home, feels like something which could be done very cheap.

[CatalinaWOW]

A substantial fraction of California homes already have a 30k gallon tank, called a swimming pool.  Adding pumps and plumbing is a low cost option.  Some bright guy could rig up an Arduino with appropriate sensors to start the flooding.  Seems like an appropriate risk reduction measure.  Remember that for all the horror in the news only a tiny, tiny fraction of the housing stock burns in these fires.  It doesn't warrant cost is no object solutions.

[SilverSolder]

A substantial fraction of California homes already have a 30k gallon tank, called a swimming pool.  Adding pumps and plumbing is a low cost option.  Some bright guy could rig up an Arduino with appropriate sensors to start the flooding.  Seems like an appropriate risk reduction measure.  Remember that for all the horror in the news only a tiny, tiny fraction of the housing stock burns in these fires.  It doesn't warrant cost is no object solutions.

Perfect solution!  -  make a swimming pool required in the risky areas, per building code.

[free_electron]

it is now worth $390k.

That must be either a very small house, or somewhere remote. I can't find anything below 1 million $. Up on communication hill a 3 bedroom begins at 1.4 million . Want a teeny little patch of land , barely enough for a table and 4 chairs and 20 square feet of grass ? that'll be 2 million please.

[free_electron]

But here's the thing:  The cost to maintain electricity to the meter is paid for by energy consumed through the meter.  If PG&E isn't selling kWh, they can't afford to maintain the system at the residential level. 

Let them deal with the industrial customers. Individual homes should be solar , no selling electricity into the grid, and a connection for nighttime , or off-season use only. That would lighten the load on the grid.
Stick a 20KWh pack in the garage.

To be effective, an array probably needs to be around 8 kW in the Sacramento area.  We had that size and it covered all of our kWh for the year.  All we paid PG&E was the $5/month meter charge.  We were paying $0.15/kWh to the solar company instead of $0.35/kWh to PG&E

perfect !

One of the rules:  You can't be a 'net generator'.  PG&E doesn't want to buy back solar energy.

There's no need. Whatever excess you produce : dump it in a pack. And if you combine roof space for electric and warm water ... two birds with one stone.
Actually i wonder how come nobody makes cooled solar panels. Basically run a non conductive cooling fluid on the back of the panels pumped through a heat exchanger into storage for warm water.
Cooling the cells gives ore efficiency and you get free warm water ... Even if the cooling shuts down , or there is enough warm water : it won;t damage the cells as they are already capable of handling the full heat.

Battery systems are going to be a maintenance nightmare.

Not really. And it doesn't have to be pure battery . bloomboxes look interesting. Anyway, for night time use you would still pull additional (but reduced) power form the grid.

I'm not sure that battery systems can provide enough kW to cook Thanksgiving dinner.  One of the things about solar is that it is useful for kWh but not so much for kW.  I doubt I can afford a battery system large enough to run a 5 ton HVAC unit along with the usual kitchen appliances along with another couple of horsepower for a garbage disposal and the all important well pump (also 2 HP, I believe).  There's a reason the house has a 200A service.

52KW inverter enough for you ? Size of two shoe boxes. That easily 200 amps at 240 volts.

I have a 5 ton AC and electric range. 120 amp service. no problems. 200 amps is excessive. You only need it for night. Nights are cooler, less AC consumption. You really only need power for fridge/freezer ,interior lighting.
I have a very efficient AC system ( variable speed scroll compressor with variable speed furnace/exchange ). It maintains the house at fixed temp throughout the year. i cut my summer electricity bill in half by switching to such a system. no more bang-bang approach to cooling. OK, the system cost money i will probably only start recuperating after 10 or more years, but it can be done. It lightens the load ont he battery pack.
You need to shift and adapt new technologies to work on a pack based system, but the machinery does exist.

[DimitriP]

Actually i wonder how come nobody makes cooled solar panels. Basically run a non conductive cooling fluid on the back of the panels pumped through a heat exchanger into storage for warm water.
Cooling the cells gives ore efficiency and you get free warm water ... Even if the cooling shuts down , or there is enough warm water : it won;t damage the cells as they are already capable of handling the full heat.

Higher price, less competitive , less sales, less profit.

As for having a variable speed A/C compressor....in this day and age why do they even manufacture non variable speed A/C compressors?  and if SEER 17-24 is a good thing why are still SEER 10-14 on the market?
You'd think economics of scale would make up for
Higher price, less competitive , less sales , less profit.
Hmmm.....

[BravoV]

Actually i wonder how come nobody makes cooled solar panels. Basically run a non conductive cooling fluid on the back of the panels pumped through a heat exchanger into storage for warm water.
Cooling the cells gives ore efficiency and you get free warm water ... Even if the cooling shuts down , or there is enough warm water : it won;t damage the cells as they are already capable of handling the full heat.

[gerts]

Here's a data point from a californian (south bay area) about 200 miles from active fires up north.  Been out of power since 8pm Saturday.  Power is supposed to be restored tonight (48hr blackout).  Here's the irony.  I live in in a rural, high fire danger, grassy hill area.  I depend on electricity for water (private well).  Hope there's no fire on my property!

ps.  I'll be rectifying this with a new generator - current one only has 120v circuits.

[rstofer]

Installing a permanent generator with transfer switch is a pretty big deal.  First problem:  What fuel?  Gasoline is kind of ugly because of storage.  LPG might be ok if the fuel economy was workable.  Natural Gas might be the best choice and would be ideal if the generator was "Dual Fuel" with LPG.

I really don't want to use gasoline because I don't want to store it.

Watch the "Starting kW" rating and see if your well pump will actually start.  Just for a number, assume 1000 Watts per HP running and as much as 6 times that for starting.  I'm guessing that my well pump is 2 HP so I would be looking for a generator that has a 12 kW starting capability.

Apparently this Briggs & Stratton 12 kW generator will empty a 5 gallon Propane tank in 2 hours.

https://www.amazon.com/Briggs-Stratton-40531-Generator-Symphony/dp/B017K0QDPI

It won't support our 5 Ton HVAC system, I would need to get a lot more serious before I starting looking for something that will start the well pump.

So far, we haven't been impacted.  The major high voltage lines run right through town and if those go down, half the state goes with it.  That's why PG&E hasn't been shutting down the major transmission lines.  Too many customers would be impacted.  Of course, they have gone down before.

[maginnovision]

Rural you typically have an lpg tank on your property anyway. Unless you're strange and have electric heaters, water heaters, and oven in rural California. 

Near me Arnold and LeBron both had to evacuate. Another sepulveda pass fire. Last time some homeless people started the fire, see what it is this time.

[Someone]

Why isn't it more common to build houses out of more fire resistant materials like brick and steel in high fire risk areas?

or at least ..... https://californiachaparralblog.wordpress.com/2018/12/07/exterior-fire-sprinklers-saved-188-properties-wet-homes-dont-burn/

Wonder how practical this really is.  System needs to be isolated and self contained.  Power source for the pump and water source. That link calls for a 10k gal tank which isn't a small item.  Does the typical CA lot in these areas have enough space for this?

Just trying to get an idea of the water required...

https://www.forestry.umn.edu/sites/forestry.umn.edu/files/cfans_asset_183520.pdf

60gpm?  So your 10k tank is just under 3hrs of runtime.  Better have perfect timing on activating that.  That said some are running these systems for hours prior to a fire to wet everything.  That's a ton of water in an area that doesn't have an massive supply for starters.

Seems pretty costly and the maintenance on these is probably alot more than most homeowners are capable of.

Not uncommon for rural properties in Australia, some places expect a fire on a 5-10 year cycle. Maintenance on a small petrol powered fire pump is almost nonexistent and you run a test/practice/drill once or twice a year to check everything and everyone is ready to go. They are predominantly advertised for reducing the threat of embers (which can be mostly addressed through appropriate building materials and design) and planned for a few hours run time to be used in combination with people actively defending the property. So its not about getting the timing perfect, you only turn it on when its actually needed.

This is what it looks like from the inside:
https://www.abc.net.au/news/2019-09-09/ember-attack-during-bushfire-on-the-sunshine-coast/11494188
Proper clothing allows prepared people to keep fighting the fire during that, until the front approaches and they need to take shelter from the direct radiation.

[NiHaoMike]

Rural you typically have an lpg tank on your property anyway. Unless you're strange and have electric heaters, water heaters, and oven in rural California. 

California winters are very mild, a heat pump will be cheaper to run than getting propane.

[maginnovision]

Rural you typically have an lpg tank on your property anyway. Unless you're strange and have electric heaters, water heaters, and oven in rural California. 

California winters are very mild, a heat pump will be cheaper to run than getting propane.

I guess snow is pretty mild? It snows at my dads every winter. Anyway, even if you didn't use gas for home heat you'd still use it everywhere else you can.

[NiHaoMike]

In warmer climates, modern heat pumps can get competitive with natural gas (especially after factoring in service charges!) and will be cheaper than propane in all but the coldest climates.

[orion242]

Not uncommon for rural properties in Australia, some places expect a fire on a 5-10 year cycle. Maintenance on a small petrol powered fire pump is almost nonexistent and you run a test/practice/drill once or twice a year to check everything and everyone is ready to go.

Petrol, if your not putting additives in the fuel and running it monthly, its almost certain the carb is going to get hosed up.  Per the reports linked above, a fair deal of the systems couldn't be activated from lack of maintenance or because they where drained for winter.  Can see many that forget about them until they need it, and it won't start.

planned for a few hours run time to be used in combination with people actively defending the property. So its not about getting the timing perfect, you only turn it on when its actually needed.

Which is fine if you plan on staying behind.  Not sure that's something I would be up for unless I had a large margin around the property and a crap load of water at hand.  Assuming most are going to head for safer ground when the evacuation order comes.  Chance of burning alive or insurance claim...hmm.

[Nusa]

Rural you typically have an lpg tank on your property anyway. Unless you're strange and have electric heaters, water heaters, and oven in rural California. 

California winters are very mild, a heat pump will be cheaper to run than getting propane.

While it's certainly true that most of the population enjoys mild weather, especially near the coast, it's a big state with a lot of climates. It holds the record for the hottest (Death Valley) AND coldest (Bodie) spots in the continental US for 2018. (Obviously Alaska wins cold if one includes it.)

[orion242]

In warmer climates, modern heat pumps can get competitive with natural gas (especially after factoring in service charges!) and will be cheaper than propane in all but the coldest climates.

Natural gas is cheaper than propane typically.  In the north, air 2 air HPs aren't too useful once temps drop below the teens.  Some of the newer systems do better, but they still fall over to electric resistance during design days.

Would be interesting to run the calcs in a few areas on a modern 2k sqft home and what kind of storage and solar install would be required for HVAC & normal electrical use.  Given its nearly unheard of, I'm guessing the additional cost has a payback that's several times the average length of ownership.

[orion242]

Could be as simple as a central A/C condensing unit connected to some copper tubing placed inside some storage tanks, then use a pump to circulate cold water through some radiators. Not much more complex than a conventional A/C.

And you need condensation pans and piping under all these radiators.  All your piping needs insulation or its dripping all over.  Pipe insulation in resi isn't something I have seen unless the HO added it later.

The storage tanks are fiddly.  You need to keep the liquid level full and prevent "over" freezing and bursting them.  Figuring out and sensing the sweet spot reliably is a real PITA in commercial systems that have been doing this for years now.  Seen more than one storage tank split wide open due to a failure to sense fully charged.  You have pumps that need to circulate the fluid that's just eff losses vs a normal forced air system.  In the end you still have to deal with electrical needs that require batteries.

[NiHaoMike]

Would be interesting to run the calcs in a few areas on a modern 2k sqft home and what kind of storage and solar install would be required for HVAC & normal electrical use.  Given its nearly unheard of, I'm guessing the additional cost has a payback that's several times the average length of ownership.

Just check the off grid sites, there's probably an install somewhere of your description whose owner is willing to share data. The climate would obviously make a big difference in the HVAC and solar needed, but the battery capacity would be mostly determined by other factors if thermal storage is used for HVAC.

And you need condensation pans and piping under all these radiators.  All your piping needs insulation or its dripping all over.  Pipe insulation in resi isn't something I have seen unless the HO added it later.

The storage tanks are fiddly.  You need to keep the liquid level full and prevent "over" freezing and bursting them.  Figuring out and sensing the sweet spot is a real PITA in commercial systems that have been doing this for years now.  You have pumps that need to circulate the fluid that's just eff losses vs a normal forced air system.  In the end you still have to deal with electrical needs that require batteries.

The pumps and fans would only use a few tens of watts if they're the really efficient BLDC type. Ducted systems have pretty high losses unless the ducts are oversized, something corner cutting HVAC installers rarely do.

Sensing when the tanks are frozen to design capacity does pose some challenges, most likely it would be easiest to leave some air space for expansion and consider them "full" when the temperature suddenly drops indicating the lack of additional water to freeze. Could also experiment with things like ultrasonic sensing or detecting the size of the air space.

All in all, it's a good research area just like solar thermal air conditioning using calcium chloride. Most likely the two would be complementary technologies.

[orion242]

The pumps and fans would only use a few tens of watts if they're the really efficient BLDC type.

BLDC pumps in the capacities you need for a modern house ok.  What do those cost?  Never seen them in the commercial space, so I assume these are going to be pretty costly and not readily available.  Cooling the dT of the fluid / air is far less than heating typically requiring higher flows.

Sensing when the tanks are frozen to design capacity does pose some challenges, most likely it would be easiest to leave some air space for expansion and consider them "full" when the temperature suddenly drops indicating the lack of additional water to freeze. Could also experiment with things like ultrasonic sensing or detecting the size of the air space.

Been there done that with ultrasonic and many other methods.  Its "fiddly" and the system can easily be destroyed the first time you fail.  KISS is return temp and pay close attention to the delta T, but that's not a fool proof method either.  The feedback of over / under charged are very close to the noise floor.  One needs a few safety checks at minimum and solid understanding of the system to avoid destruction.

All in all, it's a good research area just like solar thermal air conditioning using calcium chloride. Most likely the two would be complementary technologies.

I think the idea has merit over trying to use batteries alone to provide HVAC needs to a house.  This is just cooling needs, thermal storage for heating doesn't go far.  The cost & complexity is still likely ROI than never computes in all but the rarest cases.