The Concept of Fuel Economy: Does it Lead to Good Decisions?
If you own two vehicles, a car and a SUV about the same age, then you will inevitably be faced with the decision of which car to replace first. If saving fuel is one of your motives, then you might be interested in this quick miles-per-gallon-math from Technology Review.
Say you’ve got two cars in your garage. One of them gets 34 miles per gallon; the other gets only 12. You drive both cars 10,000 miles in the course of a year.
Would you save more gas by a) trading in the 34-miles-per-gallon car for one that gets 50 miles per gallon, or by b) trading in the 12-miles-per-gallon car for one that gets 14 miles per gallon?
New experiments suggest that people tend to pick a). After all, a 16-miles-per-gallon improvement seems better than an improvement of just 2 miles per gallon.
The right answer is b).
If you start driving the 50-miles-per-gallon car instead of the 34-miles-per-gallon car, you’ll save 94.1 gallons of gas per year.
If you start driving the 14-miles-per-gallon car instead of the 12-miles-per-gallon car, you’ll save 119 gallons per year.
The math is simple arithmetic. Divide the total number of miles driven (10,000) by the miles per gallon to get the total gallons used to drive that distance. For 12 miles per gallon, the answer is 833. For 14 miles per gallon, it’s 714.
So what do you think — is “mpg” a good indicator of fuel economy?
Diesel & Gasoline Prices Slip: First Time Since March 08
The average price of gasoline and diesel fuel in the U.S. has started to slip in recent weeks. Last week the average price of gasoline was $4.10 per gallon, and diesel fuel was $4.65 per gallon.
Tens of Thousands of Tennesseans Expected to Switch to Plug-in Vehicles within Next Five Years
The Republican Senator of Tennessee, Lamar Alexander, said this week that he expects tens of thousands of Tennesseans to switch to plug-in electric vehicles or plug-in hybrid vehicles at least partially powered by electricity within the next five years.
The TN Senators met with representatives of auto manufacturing companies, battery producers, and Chairman of the Tennessee Valley Authority (TVA), Bill Sansom, who offered a 20 percent discount of off-peak electricity (i.e. outside of noon to 6 PM) that would encourage adoption of plug-in vehicles with batteries that could be charged cost effectively during off-peak evening hours.
According to Energy Central News, TVA carries an excess generating capacity of roughly 7,000 megawatts in the evening, equivalent to the generating capacity of roughly six or seven nuclear power plants.
The top selling hybrid car in the U.S., Toyota Prius, is also the most fuel efficient car sold in the U.S. with an average fuel economy of 48 miles per gallon. GM sells several hybrid vehicles as well.
In contrast to non-plug-in hybrid vehicles (HEVs), plug-in hybrid vehicles (PHEVs) need to operate in a long-range charge depleting mode, which requires deep discharge of the battery’s energy over time. A123 Systems develops affordable PHEV cells, based on nanophosphate lithium-ion battery technology, with the following innovations:
- Higher energy density for long-range (100+miles), charge-depleting, all electric PHEV operation;
- Retention of high power for charge-sustaining PHEV operation;
- Thousands of deep discharge cycles for successful, long-term PHEV operation.
The following graph illustrates how the A123 PHEV cells maintain their energy capacity over thousands of deep discharge cycles.
Corn and Switchgrass Ethanol, and Used Cooking Oil Biodiesel
Corn Ethanol
To grow staple food crops like corn in the U.S. to convert to fuel is not a viable solution for the automotive industry because, well, people really like to eat corn. Besides what would happen to corn ethanol if the U.S. Congress eliminated the 54-cent tariff on each gallon of imported ethanol form places like Brazil? Brazilian sugarcane requires about half as much land and far less fossil-fuel input than U.S. corn to produce the same quantity of ethanol fuel. Having no shortage of sunshine, rain, and arable land, Brazil would certainly have a leg up in the ethanol market.
Switchgrass Ethanol
Is American switchgrass (a native prairie grass) a viable, alternative feedstock for ethanol fuel? Well, unlike corn, people don’t like to eat popped switchgrass, creamed switchgrass, switchgrass muffins, etc. so food shortage is not an issue for swtichgrass ethanol makers. Wild birds, pheasant, quail and turkey enjoy switchgrass as a habitat, but that isn’t a big problem. The major problem is feasibility. Engineers and entrepreneurs must find a commercially viable way to convert cellulosic biomass into ethanol. There is some progress with a demonstration-scale biorefinery that opened in 2008 in Jennings, LA. However this plant makes ethanol from a cellulosic feedstock called bagasse that is left over from processing sugarcane to make sugar.
Used Cooking Oil Biodiesel
While corn ethanol is heavily subsidized in the U.S., biodiesel derived from used cooking oil is a feasible alternative (a drop in the bucket) to conventional diesel fuel due to the abundance of free used cooking oil available from restaurants. Used cooking oil would only be able supply less than 1% of the 65 billion gallons of diesel consumed annually in the U.S. One small business in California, called Blue Sky, collects used cooking oil from restaurants free of charge, refines it and then sells it to diesel fleets (e.g. school bus fleets) which run on 20% biodiesel and 80% conventional diesel. Blends of 20% biodiesel with 80% petroleum diesel (B20) can generally be used in unmodified diesel engines.
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EIA: Retail Prices
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