Why a plug-in?

Because electricity is much less expensive than gasoline and MUCH less polluting in nearly all circumstances except maybe diesel generated electricity.

Plug-ins also utilize larger capacity batteries which help push fuel milage even higher so there is less fuel use in general.

 

The cost per mile to drive a PHEV is lower today than to drive a regular hybrid. As gas prices continue to rise, that price gap will widen. Further, my power is supplied by a nuclear power plant. No greenhouse gases from that.

 

A little research will tell you all the answers. Briefly: much lower fuel cost per mile (ie, combined gas/electric cost per mile), reduced C02 per mile (with the possible exception of people whose electricity is produced entirely by old coal plants, as is the case in (say) Minnesota), substitution of domestic coal/nuclear/hydro for imported oil. And, for the truly paranoid, the ability to use your car even if there are spot shortages of gasoline. If recharge occurs at night, there are substantially higher pollution and cost benefits for the utilities, and we could convert nearly the entire US fleet to electric miles before additional generating capacity was needed (due to 50% peak-to-trough day-to-night demand for electricity now). But if recharge occurs during the day, we would have to add generating capacity.

For the Hymotion conversion (and, I assume, the others), the car operates as a normal Prius once the battery pack is exhausted (so you don't recharge the battery from the gasoline engine, solely from the grid). And most drivers drive very few miles daily, so the ranges being discussed will cover a large fraction the typical driver's daily miles. (Not everyone, obviously, but true for many.) The net effect of that is that a PHEV with 30 or 40 mile range gives the typical driver almost all the benefits of an EV without the limitations. In effect, it economizes on the batteries.

But the big issue remains the cost (and now to a lesser extent) the longevity of the batteries. A PHEV will beat the @#$ out of the battery pack because it is designed to go from full charge to totally empty every day, far more abusive than (say) the typical RAV4 EV driving pattern. The Hymotion conversion, at $10K+, is unlikely to be cost-effective over the life of the vehicle, but it does appear that the batteries will last the life of the vehicle.

So current adopters are doing this for reasons other that out-of-pocket cost. But it looks like it's only a matter of time before this becomes more common and more affordable.

 

Don't forget those lucky souls who generate their own electricity on their roof or via wind. Properly equipped, they can fuel their PHEV without generating any pollutants at all. I can't think of a more ideal situation utilizing current technologies. Some priuschatters fuel their electric vehicles with self-generated power today. I hope to have this kind of arrangement at some point in the future. <looking into the distance while eyes glazing over...>

 

Depends upon your location; here in southern CA electricity unit prices rise as your consumption increases. At the top residential tier (which I am in) the kWh price is around $0.38. Meanwhile some midwest locations are paying $0.07 or $0.08 per kWh.

 

It's the same up here but even so if you are at the top tier you should be making some changes to reduce your consumption. My roomate is at the 3rd tier and I think pays around $0.22 per kWh and we are working on lowering his consumption then maybe adding solar. He has a pool and a spa.... The big dummy

 

I have a ~20,000 gallon pool and spa which require 5 hours of filtration per day. A 2 hp motor running 5 hours per day takes lots of electricity. A pool of that size is "required" for the homes in this area, which gets quite warm in the summer. Until I am ready to sell the house, I must maintain its various amenities...

 

You are WAY behind the times. Isn't it illegal to even sell a single-speed pool pump in California now? I USED to have a 2hp single-speed motor on my pool. I also used to run it 12-14hrs per day during the hottest part of summer. At 75% efficiency, that's almost 30kwh of electricity per day. I've since replaced it with a Pentair Intelliflo VS-3050 variable speed motor and cut my electricity use by the pump by nearly 90%. Here's how it works:

For most people, the full 2hp is only needed to run water features like a waterfall, or your spa jets. Filtration doesn't need anywhere near 2hp. Also, because of frictional losses at high flowrates, it's far more efficient to run your pump at a lower speed, but run it for longer periods. Roughly speaking, power consumption is proportional to the cube of water flow, so going from 60gpm to 30gpm cuts your power consumption by nearly 90%. Also, in a properly maintained pool (using a chlorine generator or liquid chlorine injection, NOT trichlor tablets), it's sufficient to turn the water over once or 1-1/2 times per day.

So you buy a variable speed pool pump for $850, minus whatever rebates the power company will give you ($200 in my case), and run it at half the flow or less of your existing pump, you reduce your power consumption by up to 90%. Even if you double the run time to make up for the slower filtration, you can still save 75% (1-2*(1/2)^3). If you need to run your solar panels or your vacuum, just have your automation system run that for a few hours a day on a higher pump speed (still doesn't need anywhere near that full 2hp).

I love my Intelliflo VS-3050. It is whisper quite when filtering. When I crank it up for vacuuming, it's about as loud as a small aquarium pump, and only when the spa is running does it even sound like a motor is running.

P.S. Breakeven point (~$800 installed) for some people may be as little as ONE pool season. For me it will probably be more than one but less than two full seasons.

 

Thanks for the info, this is quite interesting.

The house and pool are ~14 years old, so the pool design reflects the technology available and design trends fashionable at that time. The pool/spa setup includes three pump motors: 1 for the pool (or spa), 1 to provide boost pumping for the spa, and 1 for the spa waterfall. The pool has two waterfalls that always run, while water pumped into the spa drains into the pool via three waterfalls. I am using a Hayward Navigator pool sweep.

I understand your point that pumping for a longer period at a slower rate can conserve electricity, but am not sure how a new variable-speed motor will integrate with the existing pool/spa control electronics. So the electronics probably also have to be replaced which may well run into 4 digits.

 

I hang out on the forums at troublefreepool.com so I've picked up a lot of info on saving costs (not just electricity) there. Some very sharp people there.

You're correct about the cost of automation. My pump is controlled by commands over an RS-485 serial port, which only Pentair automation systems can generate natively. For other brands, there is a $300 device from Pentair which translates relay closings (from the foreign automation system) into the RS-485 commands for the pump. So you could dedicate two to four relays on the non-Pentair system to choose two to four different speeds on the pump. I've found I really only need two speeds, one for normal filtration and vacuuming, and one for maximum filtration and vacuuming or spa. The two other speeds I've programmed on the pump (you can program the rpm of each of the four selectable speeds) are the lowest (700rpm, winter filtration) and highest (priming), and don't need to be selectable via the automation system.

There are also two-speed pumps available which might find use in your application. Not as flexible as a variable speed pump, but often in a multi-pump installation only one VS pump is required. Two-speed pumps are easily controlled with existing automation systems or even simple mechanical timers (one timer to determine on/off, the other to determine hi/lo). And of course you save on power costs when you run on low speed.