Using PIP As A Generator

I've proven that point with the real-world numbers I've posted on this forum, and on the forum I link to in my signature. It is actually more efficient to use my Prius than it is to use my inverter-genset Honda EU3000is.

 

Well yea - anytime you use a genset that is only 120v it will be less efficient than a 240v genet. Usually the difference will be around 15%. You ought to compare the 240v Honda EU-6500 or larger if you want to be fair, & compare apples to apples. The little toy 120v generators like you compared to is really no comparison. The high quality Prius backup power inverters can output 240 volts - so you really need to look at apples to apples. But again every person's needs and affordability considerations are primary issues. It's not so much a question of which is better but rather which is most affordable turning on what the individual needs and technical skills are.
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Actually the operating specs are fairly close, much closer than the EU6500is (which my parents have and it uses a decent amount of gas, about 10 gallons per day or about 0.40 gallons/hour). I'm seeing 0.13 gal/hr on the Prius, 0.15 on the EU3000is.

 

No one is calling you a liar. You made your point, and I've made mine.

 

back of the napkin - .13 gallons would be a teeny bit over 2 cups of gas. The total theoretical energy in 2 cups of gas would be 4kWh (including non usable heat loss). Then, there's parasitic loss in just having the Prius ignition turned on .... ~250Wh. At this point just counting conversion loss going from battery storage back to AC power .... not even counting for a small amount of friction loss while the ice runs? Wouldn't it defy the laws of physics to pull more than 1.8kWh off the traction pack? 100% duty cycle of your eu3000 is what ~ 1kWh higher than that - IIRC? So it makes sense your Honda 3000 would use more gas, unless your required power is so low that the Prius gets an advantage by turning itself off constantly. I'm guessing efficiency turns on how much or little you're pulling from the traction pack or generator ... not saying one is higher or lower than the other but rather as I mentioned earlier - every tool has its purpose. That's why we have both.
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There is roughly 33.4 kWh/US gal so if you are using 0.13 per hour then you could only theoretically get around 4.3 kW per hour at 100% of the energy contained in the gas. Obviously there are going to be quite a few losses along way but even assuming both the Prius and the generator are equally efficient at converting gas into kWh's, the fact that the Prius has the advantage of a battery bank to buffer the loads (ie runs at peak efficiency then cycles on/off depending on the load) gives it a pretty significant advantage over the Honda inverter generators. I'd be interested to see what the actual VA (power) was under monitored conditions (ie logged over time with same loads on both the Honda portable and Prius/UPS setup).........that should provide more concrete evidence as to what the true efficiency of the system really is over time.

Here's the writeup on the setup and results:
Doug's PriUPS

Unfortunately for me it looks like all the UPS systems running 1-phase voltage are set for Prius battery input (192V nominal in UPS vs 201.6 nominal in the Prius, which is a great match). All the other including the Highlander (288v nominal), 1st Gen Prius (273V nominal) and the Camry (244.8v nominal) are bacially very limited in the number of compatible high power UPS options. So at this point I think I'll either need to buy my own 2nd gen Prius or go with my Plan B (nice 1800 RPM diesel genset).

 

Yes. I figure my house is using a few hundred watts for about 16 hours of the day (fridges, freezer, wood stove fan, dvrs), and ~1500 for the other 8 when things like tvs and lights are on. My 12 month daily average is 42 kw, but that includes loads not on the UPS (like A/C, well, and water heater). I checked the logs for my APC and yesterday's average was over 500 watts over 24 hours, which added up to about 37.6 kw for the day.

Diesels are a great choice for manufacturing and businesses, since the building load is fairly constant and known. This isn't true for homes, as I demonstrated earlier in this post. Diesels need to be loaded to at least 40% most of the time to prevent coking and other issues. However, with homes only needing a few hundred watts for the majority of the time, problems will occur over time. Now, if you are instead recharging a battery bank as the primary load each time the genset is run, then you are closer to a steady load. This is the reason you find diesels for businesses and gas/LPG/NG for homes.

 

See my reply to MTL_hihy, above.

 

I agree the larger business/commercial diesel gensets need to be loaded due to the fact they more often than not have turbos and/or may have emissions equipment, but I have to disagree on the coking for smaller gensets. There's clearly some myths circulating out there about this subject. Coking only occurs on things like the EGR system, turbocharger or catalytic converter and none of the smaller 2-3 cylinder gensets have had any of these items on them as far as I have seen. As long as you still have good cylinder compression, injector deposits are really only from using poor quality fuel and even then they can be cleaned in place by switching the engine to bio-deisel for a short period. I have a friend who converted an old 6 kW diesel construction light tower to power his house and let me tell you it's one heck of a setup (not even as loud as a portable gas genset and will supply nearly double the rated capacity in surge situations).

This type of setup also may be a good fit in my situation since I've got a diesel truck stilling in the driveway anyway so I'd have plenty of fuel at all times if needed. Gas is often hard to get during extended outages so keep in mind these small diesel gensets aren't picky on fuel either, they will burn home heating oil, waste veggie oil or even things like used engine oil (should be cleaned first so obviously it's only used in a pinch). These small diesel gensets are extremely miserly on fuel and would certainly put any gas powered genset to shame. The main issue with diesel gensets for the home is cost (very expensive new), but it is possible to get a used light tower for around $1500-3000 and they usually come on a trailer so now you can have a portable system you can bring anywhere you need it (UPS / battery based systems stay with the house) and no need to unhook your power if you are out and about during the day. The PriUPS setup is certainly slick and great in extremely lower power conditions (like overnight keeping the electronics going), but you still can't knock a small diesel genset either for both reliability and fuel economy. I really do like the idea of a diesel powered UPS system (best of both worlds)........but in the meantime I can certainly vouch for how well one of those small diesel gensets work in a home application.

 

It might be time to revisit the old concept of co-generation. I know some buildings are already doing so. It's hard to argue the virtues of using a diesel engine for both power generation and indoor heating. Years ago, a lot of apartments got their power from a genset on the roof, which circulated hot water through the building as well. Maybe some day, someone will figure out a way to plumb the cooling system of the Prius into the heating system of a house.

 

Lots of people with experience over on the Wind Sun solar forum talk about coking, wet stacking, etc. Some of them are also north of the Great Lakes where even LPG freezes up, let alone diesel. The only reliable fuel up there is gasoline. Temps may not be a factor for you, but something else to consider. I otherwise agree about the low fuel consumption, high fuel availability in a pinch, and the added bonus of enough torque to go with 1800 rpm windings in the head for reduced sound.

 

I'm curious where that was done on apartments, I've never heard of that. I would think that vibration would be an issue for the top floor.

Unfortunately/fortunately the Prius' high efficiency wouldn't make it a good candidate for that. It doesn't have much waste heat most of the time while operating as a generator since the engine is off a good bit of the time. The computer will fight any heat removal by wasting fuel just to keep the system hot enough to meet emission requirements, which then reduces the overall efficiency since that fuel isn't producing any useful electricity.

 

At risk of going way out in left-field, the concept of co-generation hybrid would be a great fit with a motorhome. I don't know if any hybrid motorhomes are being built, but it would save on mileage, and also heat the interior, if a way to run the diesel motor on fewer cylinders, according to power-demand could be designed.

 

I believe that in the early days of electricity, large power-grids didn't exist, and local generating plants were the norm in cities. Some apartment buildings with their own generators hit on the idea of harnessing the heat of combustion, and feeding it through the radiators in the building. As for vibration, I'm sure some sort of dampeners were used.

 

Cogeneration Technologies - onsite energy and thermal engineering services, cogeneration, trigeneration, district energy and distributed generation solutions

 

I assume this might be what you are talking about (notice the turbo):
Load Banks for Prevention of Wet Stacking in Diesel Generator Sets | Powercity

We have very cold temps up here (-40F) and I've never had issues with diesel freezing before (bio-diesel will go solid at those temps) but a small fuel pre-heater for winter weather will ensure you never have any cold start or gelling issues. Most people up here do run propane powered standby gensets so not sure why gas would be the only option. Even if I had one I probably wouldn't run a diesel all night unless I needed the heat pump running (should pull around 30% load) so more than likely if there were a true outage you would try to conserve fuel by only running it in the day when people are up and about. Also switching to bio-diesel for a bit (while exercising the generator) will help clean out those deposits and help keep it running well despite long periods of idling. I would still say the PriUPS has the clear advantage under very low consumption scenarios (due to the high capacity buffering the traction battery provides) but as loads increase the diesel begins to show its stripes rather quickly.

Actually that's a pretty good idea if you were looking at increasing efficiency which is always a benefit when resources are harder to come by.

 

Why dirty diesel when you can get electricity and heat from a natural gas fuel cell generator :

Doosan Fuel Cell America – PureCell Fuel Cell Systems

I'm no fan of fuel cells for cars technology - but these things are pretty good
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Few reasons....

1) We don't have a natural gas line anywhere near my house
2) Diesel has a wide range of fuels you can use in a pinch (remember this is for emergency use)
3) Fuel cells are expensive (used diesel generators are available/affordable)
4) Easy to get parts and do maintenance yourself

I would love to see a small propane powered fuel cell for use as a generator but haven't seen anything marketed as affordable yet.

 

Its expensive but they are targeting the right crowd going high end first. When the fuel cell can be manufactured cheaper they can either make the fuel cells bigger or make many smaller ones for houses. When they become affordable they provide:

1) Can co-locate them inside the house - minimal noise, no vibration, no moving parts.
2) Can also be used to heat the house.
3) Provides water vapor as exhaust.
4) Putting them inside the house helps with security and ease of hook up.

iPad ? HD

 

Looks like a tri-generation system. From Natural Gas, you get heat, electricity and hydrogen. The system is claimed to be 90% efficient.

Here is a DOE report of tri-generation success story.

https://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/tri-generation_fountainvalley.pdf