Doing the math - Hymotion vs. Gas vs. Pure Electric

[zcat3]

So with gas now below $2 - I think the national average is about $1.75, I was curious what the cost of just driving with gas vs. PHEV vs. electric is. I know everyone pays different amounts for electricity, but here in the San Francisco Bay Area, PG&E currently list an average residential rate of $.175 per kWh.

So using 200 miles as a baseline. This is what I get:

Pure Gas at 45 MPG = 4.44 gallons x $1.75 = $7.77

Hymotion PHEV: 200 at 100 MPG = 2 gallons gas = $3.50 + 32 kWh x .175= $5.60 = $9.10

Pure Electric (based on a Tesla getting 200 miles on a 55 kWH charge) = 55 x .175 = $9.625

For the Hymotion I am using my number of close to 100 MPG and 4 kWh every 25 miles.

Are these numbers wrong? Is electric currently more expensive than gas?

[bedrock8x]

It depends how much you paid for electricity. In your case it is very close but you also need to amortize the replacement cost of the battery for HEV, PHEV and EV. Many tend to ignore it to make the cost of electricity cheaper and some has solar power and claim the electricity is free without considering the initial investment.

Originally Posted by zcat3

So with gas now below $2 - I think the national average is about $1.75, I was curious what the cost of just driving with gas vs. PHEV vs. electric is. I know everyone pays different amounts for electricity, but here in the San Francisco Bay Area, PG&E currently list an average residential rate of $.175 per kWh.

So using 200 miles as a baseline. This is what I get:

Pure Gas at 45 MPG = 4.44 gallons x $1.75 = $7.77

Hymotion PHEV: 200 at 100 MPG = 2 gallons gas = $3.50 + 32 kWh x .175= $5.60 = $9.10

Pure Electric (based on a Tesla getting 200 miles on a 55 kWH charge) = 55 x .175 = $9.625

For the Hymotion I am using my number of close to 100 MPG and 4 kWh every 25 miles.

Are these numbers wrong? Is electric currently more expensive than gas?

[dr_d12]

Aren't you underestimating the cost of the electricity by assuming a kW in the battery costs a kW at the wall? What is the charging efficiency of a lithium battery?

Oh, Wikipedia says 99.8%. That surprises me. I read that our NiMH are only about 60% efficient.

[ibcs]

I guess I feel lucky, my electric is only .09 per KWH.

Hymotion PHEV: 200 at 100 MPG = 2 gallons gas = $3.50 + 32 kWh x .09 = $2.88 = $6.38. Hymotions saves $1.39 per 200 miles, but I send less money overseas for oil.

---Kent

[ghb101]

I'm no expert but from what I've read I'm thinking that your 4 kWh for 25 miles would be valid if it was all electric driving since the pack is about 5kW. However then you wouldn't need to include the gas for the calculation and you would come out with $5.60. If you using 100 MPG for the Hymotion, then I believe that the kWh would be less that 4kW per 25 miles since the ICE is working as well. Would be useful to know how many miles people with Hymotion installed travel at approximately 100 MPG before battery runs out. I'll be it is a bit farther than 25 miles ( or their MPG is higher than 100).

[ibcs]

For me it works out to be about 28 miles for highway driving.

---Kent

[PeakOilGarage]

I pay 8 or 9 cents per kwh. Mostly hydro electricity up here in the Seattle region.

For me I can achieve 41 miles from Hymotion if it is 100% highway.
My Hymotion does 23 miles if it is 100% EV on city roads under 33 mph.
Since my driving is typically a combination of both city/highway, I typically get 30 to 32 miles from the battery.

On cost of electricity, (zcat3) are you on the EV schedule with PG&E? I thought that the cost per kwh was 9 cents on the E9 schedule based on time of use costs. People who have an EV get charged the cheap rate if they recharge at night.

Martin Eberhard (Tesla Founder) has a few posts on this topic related to recharging his Tesla. Tesla Founders Blog

[Codyroo]

A quick check of PG&E's site turned up this....

For the typical PG&E residential customer that uses 550 kilowatt hours (kWh) per month, October bill increases will be roughly 95 cents from $72.13 to $73.08. In January, the bill for a typical residential customer would increase by about 35 cents more

That would be a rate of $0.133 (for Oct 2008) to $0.134 (Jan 2009). Also, the plan you are on makes a difference in rates too.

If you sign up for the E-9 rate program (available if you have an Electric Vehicle) EV, you can charge up for even less (under $0.06 at the lowest). The rates are calculated as a time of use.

Electric Vehicle Charging Rate and Economics

Finally, when we put solar panels up on our house, we switched from an E-1 rate schedule to E-7 (time of use). Off peak rates (6 pm - noon) are typically when you would be "recharging". Off peak rates are around $0.11 in the "summer" and $0.09 in the "winter" (winter = Nov - March or so). I'd have to look it up on our bills from last year.

[boxer93]

Originally Posted by ghb101

I'm no expert but from what I've read I'm thinking that your 4 kWh for 25 miles would be valid if it was all electric driving since the pack is about 5kW. However then you wouldn't need to include the gas for the calculation and you would come out with $5.60. If you using 100 MPG for the Hymotion, then I believe that the kWh would be less that 4kW per mile since the ICE is working as well. Would be useful to know how many miles people with Hymotion installed travel at approximately 100 MPG before battery runs out. I'll be it is a bit farther than 25 miles ( or their MPG is higher than 100).

ghb101,
In my experience the 4kWh is for 25 miles of combined ICE and EV Only travel. Plus like your standard Prius MPG varies greatly on conditions. Yesterday My 10Mi morning commute 15 deg F 82MPG Today same commute 55 deg F 178MPG. I run with EBH and full grill Block. Also remember the MPG is only for the fuel used for the ICE. MPG calculation for kWh vary greatly. Again in my experience I use 150-200kWh/Mi.

Chris

[zcat3]

I am on a E-7 meter as we have solar on our house, so yes, my cost of electricity is .09 per kWh in the evening (or hopefully free if we generate enough power for our house).

I looked at the E-1 PG&E standard tariff schedule, where they state the average cost of electricity in Region T (the SF Bay Area) is 17.5 cents.

I wonder if it is possible to have two meters - one E-7 meter for the solar and the house and an E-9 meter for charging the car as that is still a better rate than the E-7 solar rate?