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Discussion Starter · #1 ·
Hi, folks,

I'm considering the purchase of a used C-Max, and in the hopes of getting a better understanding of the economies of running on electricity, I did the following calculations:

Gas: $3/gallon
Typical compact IC car fuel economy: 30 mpg
Price per mile: $0.10

Electricity: $0.26/ KWH (here on Cape Cod, MA)
C-Max kwh/mi: 0.37 (from various online sources)
Price per mile: $0.09

Did I make any obvious mistakes above? Because from these number, while there might be numerous other reason to want to run on electricity, saving money is not among them.

Comments, especially corrections to my assumptions or calculations, are welcome.

-l
 

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Wow, your electricity cost is twice my $0.13 here in New Mexico. Still, I'd encourage you to go for it, just to get off of gas/fossil fuel. And add to your wish list a solar PV system for your house and car, that will pay for itself in a very few years (guessing about 5 years).

Oh, and keep rooting for the Mighty Red Sox!
 

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Discussion Starter · #3 ·
We did 14 KW of PV in our last house, but that was a 4400 square foot monster with an electricity-sucking geothermal HVAC system. This house is considerably smaller, 100% LED lighting, and all the heating appliances are natural gas. Except for air conditioning in the summer, we just don't use much electricity. I did the math and it didn't look like it made sense, but given the volatility of utility prices, perhaps I should take another look.
 

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We did 14 KW of PV in our last house, but that was a 4400 square foot monster with an electricity-sucking geothermal HVAC system. This house is considerably smaller, 100% LED lighting, and all the heating appliances are natural gas. Except for air conditioning in the summer, we just don't use much electricity. I did the math and it didn't look like it made sense, but given the volatility of utility prices, perhaps I should take another look.
Wow--14KW largely due to geothermal HVAC. I'm just looking into heat-pumps for hot water and baseboard heating for a similar (monster) passive solar adobe. Does a new heat pump still suck protons?
 

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Discussion Starter · #5 ·
The geothermal system in question was installed in 2010. The issue is the direction the heat pump is running. In our location, groundwater is typically about 50 degrees F. So in the summer, the system is pumping "downhill", that is, warm to cold, the direction the heat naturally wants to flow. So it's efficient as h*ll - we air conditioned the entire place for $50/month in the middle of the summer, and as my wife has asthma, we ran it pretty much all season.

In the winter, it's pumping "uphill", cold to warm. A typical February electric bill was $750. Ugh.

If I someday live in someplace like Florida, where most of the HVAC is AC, I'd definitely do it again, But as a heating system the overall experience was pretty awful. I was thinking about modifying the system to heat with natural gas and retain the geothermal for cooling, but them we moved.
 
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