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"60.0 kilowatt-hours of energy (equivalent to about 1.8 gallons of gasoline)" Interesting. Just for an oranges to apples comparison, I wonder how many KWh the

"60.0 kilowatt-hours of energy (equivalent to about 1.8 gallons of gasoline)" Interesting. Just for an oranges to apples comparison, I wonder how many KWh the most efficient gas powered generator can produce on 1.8 gallons of gas.

brianlweiner 10y ago
Literally posting one of the first google results so I cannot guarantee accuracy. "The gasoline-powered generators produce at best 6.13 kilowatt-hours per gallon of fuel, at worst 4.42, and a median of 5.7." [1] So it sounds like it's ~5x as efficient as a gas generator. [1]https://settysoutham.wordpress.com/2010/05/26/portable-generators-about-half-as-efficient-as-power-plants/ https://settysoutham.wordpress.com/2010/05/26/portable-gener...
tjalex 10y ago
They covered 238 miles on a trip w/ 34 miles indicated remaining, so if they went ~250 miles total on 60 kW-h that would be equivalent to a ~140 MPG car.
sebnukem2 10y ago
Combustion engines are about 15-20% efficient. Toyota has 30+% engines in their Prius. Electric motors are about 90% efficient. So electric motors are about 5x more efficient than ICEs.
- timthorn 10y ago
  But don't forget the losses in charging the battery as well.
  - Cshelton 10y ago
    That's about 10%, and it's all heat. So to charge a 90kwh battery, you need roughly 99kwh of energy. Which for me, since it's charging in my garage, the excess heat is actually kind of nice as it will keep my garage slightly warmer in the winter and thus my house as my garage is on the lower floor. Either way, it's still WAY more efficient than any time of combustion engine. Including hydrogen. Hydrogen is kind of a wasted effort (unless we are doing fusion ;p )
- samfisher83 10y ago
  67% of electricity comes from fossil fuel. https://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3 https://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3 Efficiency of coal plant is ~ 33% http://www.eia.gov/electricity/annual/html/epa_08_01.html http://www.eia.gov/electricity/annual/html/epa_08_01.html Natural gas is about ~40%. So in reality you are getting 90% of ~35% or 31.5%.
  - parimm 10y ago
    There are combined cycle natural gas plants that can go up to 68% eff
    - samfisher83 10y ago
      That is not what it is currently for a majority of plants. Maybe there is few plants here or there, but I posted the data directly from eia.
VanillaCafe 10y ago
I don't know about the most efficient. Looking at the first result of a gasoline powered generator at Home Depot -- the DEWALT 7,000-Watt Gasoline Powered Electric Start Portable Generator -- the description states, "The 7.5 Gal. steel fuel tank provides 11 hours of runtime at 50% load." That's 11 hours at 3500W for 7.5gal == 5.1 kWh/gal. 1.8 gallons in that generator gives about 9.2 kWh. Or, 11.7 gallons to get 60 kWh. Some other quick searching says gasoline has 33.4 kWH/gal and that typical gasoline engines in cars are around 25% and the best peak at maybe 35%, giving between 8.4 kWh/gal and 11.7 kWh/gal. Which is between 5 to 7 gallons for 60 kWh.

brianlweiner 10y ago

Literally posting one of the first google results so I cannot guarantee accuracy. "The gasoline-powered generators produce at best 6.13 kilowatt-hours per gallon of fuel, at worst 4.42, and a median of 5.7." [1] So it sounds like it's ~5x as efficient as a gas generator. [1]https://settysoutham.wordpress.com/2010/05/26/portable-generators-about-half-as-efficient-as-power-plants/ https://settysoutham.wordpress.com/2010/05/26/portable-gener...

tjalex 10y ago

They covered 238 miles on a trip w/ 34 miles indicated remaining, so if they went ~250 miles total on 60 kW-h that would be equivalent to a ~140 MPG car.

sebnukem2 10y ago

Combustion engines are about 15-20% efficient. Toyota has 30+% engines in their Prius. Electric motors are about 90% efficient. So electric motors are about 5x more efficient than ICEs.

timthorn 10y ago
But don't forget the losses in charging the battery as well.
- Cshelton 10y ago
  That's about 10%, and it's all heat. So to charge a 90kwh battery, you need roughly 99kwh of energy. Which for me, since it's charging in my garage, the excess heat is actually kind of nice as it will keep my garage slightly warmer in the winter and thus my house as my garage is on the lower floor. Either way, it's still WAY more efficient than any time of combustion engine. Including hydrogen. Hydrogen is kind of a wasted effort (unless we are doing fusion ;p )
samfisher83 10y ago
67% of electricity comes from fossil fuel. https://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3 https://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3 Efficiency of coal plant is ~ 33% http://www.eia.gov/electricity/annual/html/epa_08_01.html http://www.eia.gov/electricity/annual/html/epa_08_01.html Natural gas is about ~40%. So in reality you are getting 90% of ~35% or 31.5%.
- parimm 10y ago
  There are combined cycle natural gas plants that can go up to 68% eff
  - samfisher83 10y ago
    That is not what it is currently for a majority of plants. Maybe there is few plants here or there, but I posted the data directly from eia.

VanillaCafe 10y ago

I don't know about the most efficient. Looking at the first result of a gasoline powered generator at Home Depot -- the DEWALT 7,000-Watt Gasoline Powered Electric Start Portable Generator -- the description states, "The 7.5 Gal. steel fuel tank provides 11 hours of runtime at 50% load." That's 11 hours at 3500W for 7.5gal == 5.1 kWh/gal. 1.8 gallons in that generator gives about 9.2 kWh. Or, 11.7 gallons to get 60 kWh. Some other quick searching says gasoline has 33.4 kWH/gal and that typical gasoline engines in cars are around 25% and the best peak at maybe 35%, giving between 8.4 kWh/gal and 11.7 kWh/gal. Which is between 5 to 7 gallons for 60 kWh.