Hybrids for emergency power
 

Originally posted at "Prius_Technical_Stuff," it applies to any hybrid:

We had over 226 tornadoes in Dixie and many of them sliced up the TVA transmission lines in Alabama:

Alabama tornado outbreak visuals: jaw-dropping radar and satellite imagery - Capital Weather Gang - The Washington Post

http://crisislanding.appspot.com/?cr...rnadoes_4_2011

The Tennessee River flows east to west and on its banks are the TVA power plants and hydro dams. The big cities are Huntsville, Decatur, Guntersville, Florence, and Scottsboro but the tornadoes sliced up the high voltage power lines plunging the cities, half a million people, into darkness. I live in Huntsville Alabama and here is my report.

At ~5:20 PM, Wednesday afternoon, all power was lost in my building. Under the emergency lights, I left and noticed 'no one else is here.' Regardless, I got in my 2003 Prius and drove home taking a route that avoided main routes. Every light was out so when I got home, backed my 2003 Prius into the carport and ran the contractor cord into the house:

Prius - UPS Project

Data Log:

Wed, Apr 27, 2011, 5:49 PM

Prius started with parking brake set to suppress daylight running lights. Indicated mileage:

50.3 MPG, 10.2 miles: 0.203 gallons (indicated)
0.1915 (tire size adjusted)

Thu, Apr 28, 2011, 2:30 AM

Shutdown for night after running the gas furnace to warm-up the house.

Thu, Apr 28, 2011, 7:21 AM

Restarted 03 Prius.

Fri, Apr 29, 2011

Offered and ran another extension cable to neighbor so they would have lights and TV. They offered a one gallon of gas. Coordinated pulling their plug at 10:30 PM so we could run the gas heater to warm up the house.

Sat, Apr 30, 2011

Neighbor appreciated power, having a few lights and a 7" TV, they were able to plan a trip to Kentucky.

We have a '93, Coachman RV with a full, 80 gallon tank. However, I could not noddle a hose through the filler pipe to the tank and I started thinking about how to tap it. There are two, 20 year old, flexible couplings (I doubt they are flexible now!). I went back into the house to look for a power drill and screwdriver bit and heard that Decatur had power and was pumping gas.

Found another spare gallon in car port and then drove to Decatur in wife's 2010 Prius to fill up her car and a five gallon can for the 03 Prius. Ran the house furnace that night to fight off the chill for the wife.

Sun, May 1, 2011

Drove to Decatur for another five gallons as the news reports were that we might not see power until Tuesday.

Sun, May 1, 2011, 11:34 PM - power restored

1.3 MPG, 10.2 miles: 7.847 gallons (indicated)
1.2 MPG, 10.2 miles: 8.500 gallons (indicated if closer to 1.2 MPG)

There is no need to adjust for tire size as it never moved. So the total:

112 hours, 4 days and 6 hours
7.655 - 8.308 gallons burned

~2 gallons per day, 0.07-0.075 gallons per hour

LESSONS LEARNED

I. gas generators

There were radio news reports of generators for sale, often by I-65 exits or hardware stores in the early powered areas over in Decatur. This was followed by public health and safety warnings:

1) carbon monoxide poisonings - several seen at the local hospital. The hybrid catalytic converter all but eliminates the carbon monoxide risk.
2) refueling fire risks - the small tank requires frequent attention and there were several burn cases. Gasoline spill fires are a real risk.
3) noise - you hear the other generators across the street and 3-4 houses down. But our hybrid mufflers make them all but undetectable beyond the property line.

II. testing of all loads

We bought a 42" plasma TV in September but I didn't test it. During the outage, it started running for 1-4 hours and then it would shut itself off. I suspect a 'self-healing fuse' combined with higher than expected current from the relatively lower voltage, modified sine-wave inverter. Regardless, it is under warranty and I'll take it to the shop on Tuesday.

Saturday I bought a 7" inch, portable TV from Radio Shack but my wife could not make out the audio. Also, it really is a personal TV, not an easily viewable unit. I returned in on Sunday only to pay a 15% restocking fee for a $130 part.

On Monday I bought a 27", Samsung, LCD TV to replace the old analog, bedroom unit. We're watching it tonight and once the plasma screen is back, I'll run an endurance test on the inverter while it is in the 30 day, return period.

III. hot water

I'm looking for a 'cheap', gas water heater to put in the car port near where the car is parked. I'll get a flexible, exhaust hose, like the ones used in garages and wrap it in insulation. On the next power outage (we are averaging one use per year,) I'll route the exhaust gas through the heater and use an outside faucet for cold water and an insulated water hose into the kitchen.

IV. fix the roof before the storm

The time to setup an emergency power system is when it is nice outside. Trying to jury rig something during the emergency is expensive, dangerous, and likely to not work.

The Coachman will have an easy and safe to operate fuel tank tap. It will use a brushless, fuel pump, separate from the vehicle fuel system. I know it is tempting to put in a valve but I don't want to drive down the road and discover a leaking valve. It will be a 'sparkless' pump setup with a return-to-off, key switch.

Comments? Suggestions?

Bob Wilson

That's handy. I'm not running out to buy a hybrid though :)

We camp a lot so I have plenty of resources here, not least of which is the rocket stove, multiple internet options (gsm,our isp, our neighbors different isp), cigarette lighter inverter for the laptop/etc. some garage sale generator which I will probably ONLY get around to in an emergency that can run the blower. Fireplace. Blankets, sweaters, sleeping bags, solar shower, cooler, several gallons of water, shovel, axe. Fortunately emergencies don't happen often enough here for me to lose much sleep over. A few days of roughing it is actually kinda fun.

For water heating how about using the coolant from the Prius? a pair of quick connect hydraulic fittings would work tapped in to the heater hose lines, then connect a heat exchanger, that way you are not wasting that engine heat while trying to heat water.

Hi,

The exhaust heat into a gas, water heater was low hanging fruit. But there are problems tapping engine block coolant.

When the engine coolant temperature reaches 60 C, the engine comes on to maintain coolant temperature. I only want it to come on to sustain traction battery voltage. Also, plumbing adds weight to car as well as being a pumber's nightmare. <groan>

Bob Wilson

I just noticed, you have a Coachman? as in giant RV? Why not just use it one day a year in the backyard (and its shower and heat and whatever else the house is missing)?

I appreciate you want to find new uses for hybrids, but you have "emergency" shelter/kitchen/power/shower/crapper WELL in hand already.

It was a birthday present for my wife. Little did I realize her health would soon reach a point where she doesn't want to go on trips. Still, this is what it looks like with the Prius:
http://hiwaay.net/~bzwilson/prius/pri_tow_100.jpg

I see our Prius as being the start of a co-generation system. As I've been building out the emergency systems, I'm moving towards a day when:

• natural gas - non-traffic fuel source already available at house for economical rates.
• electricity - the current two-stage inverter can be replaced by a single stage using the built-in, inverter to generate true, sine-wave power.
• heat - using the exhaust heat for hot water and in the future, absorbtion cycle cooling.

I want to exploit the engine waste heat and stop just burning natural gas for heat without getting some electrons.

Bob Wilson

Oh, it isn't one of those giant RVs with a bowling alley inside.

Well it seems you have an agenda beyond emergency power then :) Otherwise it would be hard to justify a lot of effort/expense for something that would be utilized maybe 1 day a year.

Is the plan to run the prius on natural gas at home?

Yes, in a co-generation mode. My plan is:

• 1/3d of heat energy - 120/240 AC for house power
• 1/3d of exhaust heat - hot water and possibly cooling
• 1/3d engine compartment heat - the lowest quality and a risk to engine cooling. However, reverse direction on the radiator fans could produce a nice warm breeze for the house, space heating.

What this means is every morning, the car will be warmed up, the house utility bills will shift to natural gas, and I can go to work. When I come home in the evening, I plug the car back into the house and life is good.

Bob Wilson

A few thoughts, for what they're worth.

1) I didn't see any mention of disconnecting the house from the grid lines before hooking up the Prius. You do know that the current could be a hazard to repair crews?

2) Why not get a solar water heater instead of doing all the work to hook up the Prius' exhaust &c? Gives you free hot water 365 days a year.

3) Do you really need to run a plasma TV? A few good books and a couple of LED headlamps use a lot less energy.

i, personally, kill all breakers in my box anytime the power goes out

as long as there is sun; thunderstorms and heavy cloud cover doesn't do much for solar heaters, where as you already have the heat from the coolant, and if you don't use it the radiator gets rid of it

i have a few LED light bars in my place, if the power goes out i can grab a spare battery and hook them up for light if needed

Bob, is there any guesstimate on additional costs in cogen? i.e. nat gas to electricity/heat, extra hours on the prius engine, etc?

How hard is it to get a prius to run off a nat gas hose (I want to teach my little generator how to do that).

Any idea what this works out to on a cost per kwh basis? Just wondering if your practical expereience says that a "smart grid" is actually a good way to do things, or not.

Lets do look at the numbers before naming it "smart grid" please :)

Hi,

I've been running errands today and just had a chance to get back:
1) I run extension cords from the Prius into the house and to the various loads. Until I have enough for whole house power, I'm not going to install a cut-over switch.

2) I've looked at solar hot water systems and rather than do a piece-meal solution, I'm planning a whole house solution. Meanwhile, the exhaust heat is 'low hanging fruit' and easy enough to implement.

3) We only had one TV, the plasma unit, that had a DVT receiver. The bedroom 19" unit is analog and only works when the cable system is operational which it wasn't during the outage. We did use an FM radio as backup to the TV but valley radio was only useful when they chose to simulcast with a TV station.

During a wide-area, power outage, we needed accurate, current information including the curfew, location of gas, food, and supplies, changes to traffic rules, and how to avoid impact areas. I love a good book but how do we get current disaster information?

I can't give the cost until I freeze the design but every time we go through a power outage, I learn valuable lessons. But here are my current thoughts:

• Exhaust heat - route through a 'gutted', gas fired, hot water heater. Ebay suggests prices in the $300-500 range.
• electrical power - I'm expecting to design a power-switch for two legs of MG2 and leaving the current sensor by-passed. With two legs removed, I can provide AC power limited only by how much I wish to draw from the traction battery and MG1 generator. Pulse-width modulation into a filter network should provide exceptionally clean power. The isolation transformer will be $250-350 and the rest of the bits should be about the same, call it $700.
• engine compartment heat - I'm thinking rigging up the hood so it can hinge at the front and rise up at the windshield. Then a wedge-shaped insert can form an air-tight seal and a thermostat controlled fan force warm air into an insulated, flexible duct. It will also include a carbon monoxide and smoke detector to shut it down if anything 'bad' is detected. I figure hardware ~$50 and a foam-and-glass wedge another $50 and insulated duct $200. Add some electronics and sensor, we're looking at $300-400.

As for the fuel cost, I downloaded a spreadsheet of fuel costs. It looks like for one million BTUs:

• $10.54 - natural gas
• $23.73 - kerosene (untaxed, gasoline substitute)

Now I will lose some heat compared to a more efficient, heat-only system. However, it will leave the car fully warmed up each morning so my MPG costs should go down, significantly. Best of all, loss of electrical power will no long be an issue.

Now I have found some conversion systems but the EPA has been a 'horse's ass' about conversion systems. They insist that the vehicle be re-certified with the conversion system and that is a $250-500,000 expense. However, there are . . . alternative sources. So far, I've seen:

• $500 - carburetor systems
• $2,000 - fuel injector systems

Bob Wilson

wow, ok :) maybe I'm still missing something, but why would you need to re-certify if the thing only runs on nat-gas when stationary?

and I may still be missing something, but would it not be insanely simpler to convert a used $500 stationary gas generator to nat-gas? Maybe even retro fit auto start on power outage?

You can still pickle the carburetor off the generator and keep it handy just in case.

This has also been discussed at insightcentral in relation to the G1 Insight as well. You can force regen at tickover with an IMA control mod so the car can sit ticking over. You can get about 10A at 175V dc from the system in this config via connections to the IMA battery. Not that easy and you need something that can take your HV dc supply and convert it to mains ac voltage.

You can take power via the dc-dc converter from the 12v side but that would be limited to perhaps 500w max.

I still think that tapping in to the heater core lines, installing a small ball valve and two quick connect fittings to connect to your water heater would be better then changing the hood around to capture heat, as it would put the heat where you want it via water lines and you would be using the water pump that is already on the engine so you wouldn't be adding more then about two pounds of weight for the quick connect fittings and a ball valve, it would be a fitting before and after the valve in the same line going to the heater core, very simple way to pull heat off the engine, it would also allow you to reverse the setup for warming the car up quickly in the morning by adding an electric pump inline and pulling hot water from the house and warming up the gas engine with it, getting rid of cold starts.

And a stationary generator provides power even when the prius isn't there...

This is one strange agenda.

Things here are never about "simpler" or "easier", are they? I had the same thought though, except it was a small diesel generator in my thought. :) Anyway, great project, Bob.

Bob,

You need to write a book called "1001 things you can do with a Prius" You are never out of ideas.

I have used our Prius as a generator many times now. Most famously to keep the local gourmet chocolate cafe open on Easter. Thanks to Bob for the idea.

I like your thinking. You don't just think outside the box, you have since broken it down and recycled it.

Has anyone considered running the inverter off of the ~270 V high voltage traction battery instead of from 12V? Some solar power inverters may accept the traction battery voltage. What's its voltage range anyway?

The one's I've read about used the NHW20, 04-09 Prius, and the 200V traction battery feeding a modified 3kW, UPS inverter. I've exchanged e-mails with Richard and his is a serious project.

I've seen excellent progress with the solar panel inverters but the last time I checked, they were still fairly expensive, several thousand dollars for 3kW inverters. There is a lot of work going on in this area and if I wanted a turn-key system, I would search harder. But price remains a problem and the too frequent use just for emergency power.

Anther interesting development has been in the inexpensive, 5-6kW, gas generators. One of my co-workers bought a Coleman unit for ~$350 which is impressive since in addition to the gas engine there is the power electronics. Of course they have the advantage of being able to switch the high-frequency alternator to synthesize 60 Hz. But again, these are being sold as dedicated, emergency power.

My current investigation is looking at the 33 kW, MG2 inverter that is water-cooled and already integrated in the car. When parked, MG1 can continue to provide power up to 18 kW and just needs a fuel supply, say natural gas. These are the NHW11, 2001-03 model Prius and can be bought for ~$5k. If done right, the Prius can plug-in to the house to generate power and later still deliver +50 MPG. Add hot water heating and possibly space heating, we're talking a mobile, co-generator.

Bob Wilson

2010 Prius as emergency power source
 

In 2011, we have been hammered with Irene and Lee and a spooky Halloween weekend snowstorm up here in the Northeast. Each has caused its share of damage and power outages. I was lucky and only lost power for about a day and a half where I live during Irene. But during the snowstorm, many folks in CT and MA were without power for a week or more. All of this has got me thinking about backup power systems.

I have a 5000 watt generator which until this year, I have never really had to use. I connected it during Irene so I could pump water from my deep well and run my refrigerators and otherwise live normally. However, I quickly learned that the thing is a complete gas hog, using upwards of a half gallon an hour under low loads. It's also a bear to set up. I need to roll it away from the house on an unpaved driveway and over a lawn to get it in a safe spot to run it. That is quite a struggle and I'm not getting any younger. I figured there has to be a better way.

Searched the font of knowledge and discovered Bob Wilson's well documented inverter system in his 2003 Prius. Decided to give it a try on my 2010 Prius as I too happened to have an inverter (Portawatts 1750). However, I only tested it with a small load...about 300 watts. I just wanted to see for myself what would happen and indeed, the car ran every so often as I tested the power for about an hour to running my laptop, TV, CFL and regular fluorescent lights and other small loads I might want to use during an outage. All worked great!

OK, so I had my little power "appetizer" but now I too would like to have heat in a storm as a next step. Using an Amprobe, I determined that the furnace's largest load was when it starts the 1/2 HP blower motor, 10 amps for a few seconds. Then, the load drops off to about 6.5-7 amps for the remainder of the heat cycle.

Checked the fusible link in my Prius and it says its 140 Amps...not 100. (I took a pic but as a new poster, the forum won't let me post it.)

Tried to find out more info about this on the Internet but have had no luck. My guess is that the 2010 Prius' DC to DC converter can provide more power than the 2003's but I want to be sure. I would need about 1200 watts for a few seconds to start the furnace blower. That would be 100 Amps at 12 volts. This is more than Bob could get during his 2003 heater load test. (Bob: BTW, what does your 1/3 HP furnace motor draw when it starts?)

I've also got a 700 watt rated microwave that draws about 9.5 amps for about 1140 watts. It certainly would be nice to be able to use it...when the furnace wasn't on, of course. Again, 1140 is more than Bob could get with his 2003, but IF I have 40% more with the 2010 (1400?), maybe I'm not getting too greedy.

I like the idea of only using as much gas as I need and not really having to set the thing up. I mean, I park the Prius 10 feet from the house normally. During Irene, there was no way I could easily set up the portable generator during the storm. The rain was coming down sideways...for hours. The generator and I would have gotten drenched. But if my Prius had an inverter mounted in the back like Bob's, I'm sure I could have found a couple of dry minutes early on in the storm to connect a cord and run it into the house. Juice!

As Henry Petroski has pointed out many times in his books, "There is no perfect design". Using the Prius for something it wasn't intended has its limitations and risks. However, putting it to work on an emergency basis for light loads has a lot of appeal to me. I have no plans to sell "the monster" but I'd sure like to use it a lot less...maybe a couple of times a day for 15 minutes or so to take a shower or do the dishes. It would be nice if the rest of the day I could have peace and quiet...and save gas!

Anyway, if anyone can shed any light on whether the 2010 Prius indeed can provide more power from the DC to DC converter than the 2003, that would be great. Also, if anyone else has setup their Prius the way Bob has and has any experience with either running a 1/2 HP furnace motor and/or microwave oven with it, I'd like to hear about your experiences. Thanks.

Worth noting that some battery storage for your generator and a relatively simple controller would smooth it out pretty well too, and let you use your prius as a car during emergencies, and generally allow you to use a smaller generator if your loads a peaky (and allow solar/wind input as a potential contributor)

Hard for me to get excited about something so specific to one vehicle, since there are plenty of vehicle specific forums. Out of thousands of vehicles in the EM garage, 54 of them are priuses.

Also hard to get excited about it when it is solely for emergencies, if you are having enough emergencies that this would make a significant difference in the cost/quality of life then you might want to do some re-evaluating :)

Hi,

One option is to replace the 12V battery with one having a higher "CCA" capacity which sad to say, I don't really know what the OE rating is even after service. But there are a number of alternatives.

I used a resistance, space heater, an especially well behaved load, to stress test the NHW11 inverter. What I observed was a voltage roll-off as the current increased. But you are at the cutting edge.

Now I contacted the vendor of the inverter I plan to use for my wife's ZVW30 and it has a 34 cycle, window for overload, before the current limit protects the circuit. You may want to investigate what your vendor claims.

For my wife's car, I have a high current, circuit breaker bought for RV application. The dataspec indicates it should trip before the fusible link. I'm at a conference but it is rated under 140 A so I'll get a faster action.

GOOD LUCK!
Bob Wilson

Thanks a lot for the suggestions.

BTW, I found out that while the 2010 Prius’ battery is fused at 140, the DC to DC converter output is only fused at 125. Looks like the latter (actually fusible link) sits under the fuse box in the engine compartment. If so, it might be a b**** to change. No thanks. To avoid blowing it, I’d want to stay well under the 125…and who knows how much the car draws for its computer, engine fan and whatnot in “Ready” mode? 10 amps…20? Not sure how one could guesstimate that. In any event, there would not appear to be a whole lot more power available for an inverter from the 2010 model over the 2003.

Dcb’s idea of a battery bank would free me from the worry of blowing that darned fuse…at a price, of course. All food for thought. Thanks again, guys.

Mike