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Energy in Gasoline

Energy in Gasoline. Energy in Gasoline .

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Energy in Gasoline

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  1. Energy in Gasoline

  2. Energy in Gasoline The Department of Energy [DOE] web page says that there are 124262 BTU or 36.4 kWh of energy in a gallon of gasoline. They also say that 1 gallon of diesel has 138691 BTU or 40.6 kWh of energy. I met a petroleum engineer and asked him how much energy was in a gallon of California gasoline and he said about 107000 BTU depending on the time of year. California gasoline is 10% ethanol which has much less BTU/gallon then gasoline. 107000 BTU would be about 31.4 kWh.

  3. Motor Efficiency A long time ago I was told that a gasoline engine was about 20% efficient in city driving. I was told that a diesel engine was about 30% efficient and that a turbo-diesel could approach 40% efficiency. A DC motor and controller in an electric car is about 85% efficient. An AC motor and controller can approach 95% efficiency. In addition, the voltage needed to charge a batter is higher then what the battery provides. The battery charge/discharge cycle is about 80% efficient.

  4. Energy Comparison It takes almost 20 kW from the battery to keep a small electric vehicle going at 60 mph on a level road. That would be 20 kWh for 60 miles or 3 miles per kWh. That would be 25 kWh from the wall to deliver 17 kWh to the wheels To go 60 miles in an hour would require: (17/31.4)/20% = 2.71 gal CA gasoline (17/36.4)/20% = 2.34 gal AZ gasoline (17/40.6)/30% = 1.40 gal Diesel (17/40.6)/40% = 1.05 gal Diesel - Turbo

  5. Energy Comparison In other words: 60/20 = 3 miles / kWh EV 60/2.71 = 22.1 mpg CA gasoline 60/2.34 = 25.6 mpg AZ gasoline 60/1.40 = 42.8 mpg diesel 60/1.05 = 57.1 mpg turbo diesel At a steady 60 mph on level road in a typical small car that can hold 4 passengers and luggage.

  6. Energy Consumption Note that the calculations are a rough “back of envelope” or “ball park” since the power an actual vehicle requires depends on weight, aerodynamics, tire rolling resistance, driver ability, etc. If the mpg of a vehicle is known, this data can be used to estimate the kWh needed in a gasoline to electric conversion.

  7. Energy Russ Lemon Russ@FarTooMuch.Info

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