* PERSONAL VEHICLE TRANSPORTATION COST & CARBON
Personal transportation, mostly with a personal vehicle, accounts for over 25% of total carbon emissions making it a good target for reduction. How much carbon you generate depends on what you drive, how much you drive and, to a lesser extent, how you drive. All three of these factors offer opportunity. Consider what you drive first. We have four vehicles choices: (1) gasoline of various sizes, (2) hybrid (HEV), (3) plugin hybrid (PHEV) and fully electric or battery electric (BEV). These various vehicles offer vastly different carbon and operating costs, so the choices you make are critical to carbon generation and your wallet.
Hybrid vehicle showing power going from both the wheels and the engine to the battery - from app in vehicle.
Conventional gasoline vehicles require only about 15 hp to cruise at 60 mph. However, to give acceptable acceleration, hill climbing and towing, most are equipped with 150 - 250 hp, making them very inefficient.
Hybrid vehicles use a combined electric motor and gasoline engine drive system, which permits the use of a much smaller engine without sacrificing performance. A small battery is used to capture and store the energy normally wasted in decelerating, braking, coasting or other events. This energy is then used in the electrical drive to assist or instead of the gasoline engine until the battery is discharged. Typically, for city driving, about half of the total miles will be electrically powered to double the fuel economy. Highway mileage will be somewhat less, but still 25-30% better than gasoline only.
Plug-in hybrids use a larger battery – up to 16-20 Kwh – to store not only captured waste energy, as in a hybrid, but to also accept a charge from the electric grid or solar system. This allows fully electric operation, good for local driving for ranges around 30 miles, sufficient for most in-town trips. Fully electric vehicles usually have a range around 300 miles and can be charged at home from the utility or solar, and in public charging stations for highway driving. The table below compares operating cost and carbon generation for three sizes of gasoline vehicles plus hybrid, plug-in hybrid, and fully electric vehicles.
Hybrid vehicles use a combined electric motor and gasoline engine drive system, which permits the use of a much smaller engine without sacrificing performance. A small battery is used to capture and store the energy normally wasted in decelerating, braking, coasting or other events. This energy is then used in the electrical drive to assist or instead of the gasoline engine until the battery is discharged. Typically, for city driving, about half of the total miles will be electrically powered to double the fuel economy. Highway mileage will be somewhat less, but still 25-30% better than gasoline only.
Plug-in hybrids use a larger battery – up to 16-20 Kwh – to store not only captured waste energy, as in a hybrid, but to also accept a charge from the electric grid or solar system. This allows fully electric operation, good for local driving for ranges around 30 miles, sufficient for most in-town trips. Fully electric vehicles usually have a range around 300 miles and can be charged at home from the utility or solar, and in public charging stations for highway driving. The table below compares operating cost and carbon generation for three sizes of gasoline vehicles plus hybrid, plug-in hybrid, and fully electric vehicles.
Tesla charging station.
For these calculation, yearly driving is taken as10,000 miles of local riving plus 5,000 miles of highway driving. Gasoline is priced at $3/gallon, utility electricity (U) at $0.16/KWh and highway charging stations (H) at $0.30/KWh. Solar power (S) is both cost and carbon free. As expected, efficiency depends on vehicle size, and a hybrid vehicle is very attractive. Going to a PHEV or BEV doesn't gain much if it has to be charged from a utility. Of all the choices a PHEV charged at home from solar for local driving and operated on the highway as a hybrid only with no on-the-road charging gives the lowest cost and carbon, showing an 86% reduction in both cost and carbon over a large gasoline car.
SPECIAL NOTE: An electrified car - PHEV or BEV - will get about 3 miles/KWh - some cars are now near 4. At $0.16 utility cost per KWh the per mile cost is $0.053. Matching this requires a car that gets 56 mpg on $3 gasoline. So both solar and utility electricity are worth about 2.25 times more in your car than in your home.
SPECIAL NOTE: An electrified car - PHEV or BEV - will get about 3 miles/KWh - some cars are now near 4. At $0.16 utility cost per KWh the per mile cost is $0.053. Matching this requires a car that gets 56 mpg on $3 gasoline. So both solar and utility electricity are worth about 2.25 times more in your car than in your home.
Comparison table for various sizes of gasoline cars and all three electric vehicle types. U = utility, S = solar, H = highway
Capital costs for HEVs are slightly more than gasoline-only vehicles despite being somewhat simpler. Usually, they have no belts, no alternator, no separate starter motor, no torque convertor, and a simpler continuously variable transmission. Capital costs for PHEVs will be somewhat higher because of the increased battery costs, but offer up to a $6500 tax credit, depending on price and point of manufacture.
All vehicles do better if appropriate driving habits are adopted, i.e. no jackrabbit starts, no hard braking, coasting wherever possible, and driving at speeds near the speed limit. Such driving habits are estimated to reduce operating costs by 10-15%. Anything that reduces operating costs reduces carbon generation by a similar amount.
All vehicles do better if appropriate driving habits are adopted, i.e. no jackrabbit starts, no hard braking, coasting wherever possible, and driving at speeds near the speed limit. Such driving habits are estimated to reduce operating costs by 10-15%. Anything that reduces operating costs reduces carbon generation by a similar amount.
CARBON AND FUEL COST OF COMMON ACTIVITIES
1. School drop off at 12 miles/day (3 miles one way) for 32 weeks generates 1 ton of carbon or 2% and $300/year.
2. Commuting 20 miles one way without carpooling in a 20 mpg vehicle generates 5 tons of carbon (10%) and costs $1500/year at $3/gallon.
2. Commuting 20 miles one way without carpooling in a 20 mpg vehicle generates 5 tons of carbon (10%) and costs $1500/year at $3/gallon.
FLYING - A REAL GLOBAL WARMER
Airplanes cause much more global warming than that due to fuel burning alone. For example, a round trip of 2400 miles (Appleton to Orlando) for a family of three will generate the equivalent of 6.5 tons of carbon (13% or two years of the 7% goal). Flying business or first class will double this. Reducing this carbon component requires flying less and always flying coach. If your work requires travel see if there are ways to accomplish your tasks with less flying. It is a killer.
