Additional Math Pages & Resources

Friday, September 3, 2010

FEEC Labels, Part II

Yesterday we looked at US vehicle window labels that disclose fuel economy and environmental friendliness. Today we have to ask the question: What types of vehicles might need special labels?
  • Conventional Vehicles (CV) use gas or diesel fueled engines. This includes hybrids with gas engines and electric motors where the engine propels the vehicle and/or recharges the battery.
  • Electric Vehicles (EV) used electricity stored in batteries. They are recharged by plugging into an electrical outlet. EVs do not use gasoline. EVs in the USA include BMW Mini E and Tesla. The Nissan Leaf will be an EV.
  • Plug-in Hybrid Electric Vehicles (PHEV) are dual-fuel vehicles powered by electricity and gasoline. A PHEV battery is charged by plugging into an electric outlet and has a gasoline engine capable of recharging the battery and/or powering the vehicle. PHEVs are not yet sold in the USA. The Chevy VOLT will be a PHEV.
  • Flex-fuel vehicles (FFV) (also dual-fuel or bi-fuel) can run on mixtures of alternative fuels such as ethanol or methanol. Most FFVs can use a mixture of 85 percent ethanol and gasoline. These are the most numerous alternative fuel vehicles with dozens of models to choose from.
  • Compressed Natural Gas Vehicles (CNG) burn the natural gas used in homes. They re-fuel at special compressor stations. Honda's Civic CNG is the only model currently available.
  • Fuel Cell Vehicles (FCV) convert compressed hydrogen into electricity to power electric motors that propel the vehicle. BMW, GM and Honda are selling very small numbers of fuel cell vehicles to test the technology.
Unlike the old days where everyone filled up at the same station, in the future we will have to worry about where to get fuel, putting a fueling station in our garage, battery range, what time of day to recharge, which plug and cord to use, environmental impacts, etc. So the labels are more complex.

Remember this blog is about using math we learn in elementary school when we have grown up. So here it comes - NUMBERS! MATH!

As we've said in earlier blogs, the rest of the world outside the USA conveys fuel consumption information in terms of liters per 100 km traveled. Our new labels may show gallons per 100 miles.

Using a scale showing how much fuel you burn for a fixed distance means a LOWER NUMBER IS BETTER.

When you measure fuel consumption in miles traveled per fixed unit of fuel, a HIGHER NUMBER IS BETTER.

We face some of the same challenges in conveying how much electricity a vehicle consumes.

Using a scale that shows how many kilowatts you use per mile means a LOWER NUMBER IS BETTER.

When you compare vehicles on how many miles you can travel per "charge" a HIGHER NUMBER IS BETTER.

We need new ways to measure new things. For example, if it takes 4 minutes to fill your car with gasoline or diesel and 10-20 minutes to get CNG at a station or 4 hours at home, should the label indicate that time difference? If you do this in your garage at home at night, and save 25% on the price of the fuel, does it matter?

In future blogs we'll look at the challenges of expressing environmental impact using numbers on a window label. Like this one from a UK vehicle.  Here's a test to see if you were paying attention. Which of the following is better for the environment (cleaner)?

Average CO2 emissions output of UK vehicles = 142.5 gm/km
Average CO2 emissions output of US vehicles = 424.0 gm/mi