Flexible Fuel Vehicles: The Engine

In the recent post of October 3^rd, we discussed the types of fuel that could be used in multiple-fuel engines. The Open Fuel Standard Act of 2009 (House Bill H.R. 1476) would require 80% of the cars manufactured or sold in the U.S. to be able to burn M85, E85 or Gasoline. The "85" refers to the percent of methanol or ethanol combined with 15% gasoline.

Today’s gasoline engines are made to run on gasoline with octane that ranges from 87 to 93 (87, 89, 91 & 93) on gas pumps in New England, where I live. Methanol has octane that ranges from 105 to 109 (Source: EPA, 2002 Clean Automotive Technology Program) and ethanol has octane ratings that range from 94 to 96 (Source: Renewable Fuels Association). This is much closer to gasoline’s octane ratings.

What does all of this mean? That a flex fuel engine is a compromise in efficiency.  Gasoline engines are built to have compression ratios of somewhere between 9 and 10 to 1 (9:1 to 10:1). Compression ratio means that the piston squeezes the air fuel mixture by a factor of 10, for example, between the intake of fuel and air and compressing it just before the spark plug ignites the fuel to provide power.

 Source: AutoZone Ref. Library

If you use a low octane fuel with a high compression engine, the fuel may combust before the spark plug ignites it. Mechanics call it “knock” and you can hear it when the engine is running because it sounds like popcorn in a microwave oven. Higher compression ratios mean higher pressures and temperatures and temperature drives efficiency in a heat engine, like a car engine.

If you have higher octane fuels like methanol (especially), the engine can operate at a higher compression ratio. A methanol engine can operate at an optimal compression ratio of 19.5:1 (ranging from 17:1 to 22:1 in EPA tests). This yields higher efficiencies than a gasoline engine.

A confession: In my upcoming book (Energy: The Primer, How to Distinguish a BTU from a BLT and Other Stuff You Should Know About Energy), I have a chapter entitled, "Methanol - The Other Motor Fuel." I like methanol better than ethanol as a gasoline substitute for a number of reasons: (1) Methanol can be made from plentiful coal, natural gas and ultimately carbon dioxide combined with hydrogen (when we run out of fossil fuels), (2) It could eliminate our reliance on imported crude oil,  (3) The higher octane rating will allow internal combustion engines to run more efficiently, (4) Methanol can run directly in fuel cells, ultimately displacing the less efficient internal combustion engine and (5) The world eats corn and it's the feedstock for ethanol. I would rather not have a motor fuel compete for use of a foodstuff as a feedstock.

Plug In Cars: How Many "Miles Per Gallon" Do They Achieve?

My literary agent directed me to an article in the New York Times this past week, Plug-In Cars Pose Riddle for E.P.A., which discussed how to measure the mileage of these cars. First, there are no gallons becase there is no gasoline to burn in a plug in electric car. So let's try to sort this out. We can make them equivalent to compare them.

The plug-in Nissan Leaf was described in the NYT article, so I'd like to use this vehicle as an example. Let's assume it takes 50 kilowatt-hours to charge this car during an 8 hour overnight charge. The car is designed to go an average of 100 miles on that charge, but speed, acceleration, weather, using the heater or the air conditioner, as well as the other options, will affect the range.

So how much energy is this and how does it equate to miles per gallon? 50 kilowatt-hours will require about 510,000 Btus (10,200 Btus/KwH)  to be burned at a far-off power plant to deliver that electricity to the Leaf's charger though an electrical outlet. That's the amount of energy in about 4.4 gallons of gasoline. If you travel 100 miles, you've received 22.7 miles per gallon. Not much different than a gasoline powered vehicle, with one exception: The gasoline powered vehicle will take you 400 miles on a tank of gas, rather than 100 miles on a charge.

What about cost? Residential electricity prices can range from around 6 cents per kilowatt-hour in Idaho to 30 cents in Hawaii. The current average price of gasoline in the U.S. is about $2.82 per gallon. This is a little difficult because the price of gasoline across the U.S. is in a tighter range than electricity. Let's assume the average price of electricity in the U.S. is about 12 cents per kilowatt-hour. 4.4 gallons of gasoline will cost you about $12.41. And 50 kilowatt-hours of electricity will cost you only about $6.00, on average, or $3.00 in Idaho and $15.00 in Hawaii.

Why? Why is an electric car, of similar energy efficiency to a gasoline driven internal combustion engine, less costly to run? It's because power plant fuel, coal, natural gas and uranium, are much less expensive on the basis of cost per million Btus than the gasoline you and I purchase at the pump. In a recent post, I reported that at $3.00 per gallon, gasoline cost $26.00 per million Btus. Currently natural gas is $3.42 per MMBtu at the well head and coal will cost an average of $2.26 per MMBtu in 2010 at the mine mouth. One has to add the cost of transport to make the comparison, however, it will not increase the cost by an order of magnitude.

Cloud (Celestial?) vs. Terrestrial Computing: The Energy Use

Amanda Mecke, my literary agent, pointed me in the direction of a very interesting article, How Energy Efficient is Cloud Computing? by Lisa Zyga (Oct. 8, 2010), about the energy used in cloud vs. desktop computing. The article cites an IEEE (The Institute for Electrical and Electronics Engineers) study that reverses the original thought that cloud computing is more energy efficient than desktop computing.

Not originally considered was the energy used in transporting the data from home or office computers, which is higher yet than what the servers consume in the data center. “While previous studies of energy consumption in cloud computing have focused only on the energy consumed in the data center, the researchers found that transporting data between data centers and home computers can consume even larger amounts of energy than storing it.”

And the data center can be in a different city, state or country, increasing the energy consumption for greater distances. Power consumption in the data centers alone is predicted to double from 2007 to 2020. “Specifically, power for transport can be as low as 10% and 25% at low usage levels for private and public storage services, respectively, and nearly 60% and 90%, respectively, at high usage levels.”

Does anyone find themselves sending fewer signals into the cloud from desktop computers, cell phones, blackberries, laptops, netbooks, iPads, etc. any less as life goes on? I don’t. I just ordered a Kindle with the nearly 10 inch screen and constant, global 3G connectedness. Did I give a first thought to the power it will consume for the years I will own it? Alas, nay. I wanted it. I bought it. I’ll use it. I need it. At some point, I’ll wonder how I ever led my Neanderthal-like existence without it. Like all of you, I’m more than willing to use the additional energy.

A note about personal experience: Since the first laptop was put on my desk (more decades ago than I care to divulge), I’ve always powered down before I left the office each night. Recently, my IT department (you know, the guys who think they’re protecting the system from me and you; and who I think should run the system to serve me and you!) directed us to never shut down our computers again.  Seems they want to be able to load software and do diagnostics from their “cloud” while we’re all sleeping on ours. More energy use without a first thought. Take a look at the article.

Flexible Fuel Vehicles – The Fuel

In an earlier post, The Path from Coal to Hydrogen, I discussed a House bill requiring auto engines to run on multiple fuels: ethanol and methanol blended with gasoline, gasoline only and biodiesel.

Since methanol and ethanol do not contain as much energy per unit volume, for example, a gallon, as gasoline, we have to look at it a little differently. Take a look at this simple table:

Heating Value	Gasoline	Diesel Fuel	Methanol	Ethanol
BTUs per gallon	116,090	128,450	57,250	76,330
BTUs per pound	18,676	18,394	8,637	11,585

The figures are from the American Petroleum Institute. When we think about gasoline, the standard we use is miles per gallon because we all buy a gallon of gasoline that contains a similar amount of energy. However, when we begin to use other fuels, a gallon is no longer a standard measure of energy content. We have to go back to the basic energy measure, the British Thermal Unit or BTU. As a refresher, a BTU is the amount of energy required to raise one pound of water one degree Fahrenheit.

A gallon of gasoline costing $3.00 would require about two gallons of Methanol (theoretically costing about $1.50 per gallon) and about 1-½ gallons of Ethanol (costing about $2.00 per gallon). These would be the equivalent costs for the same amount of energy—BTUs—to fuel an engine.

Cost per BTU, just for purposes of illustration, would be $3.00 or 300¢ (cents) divided by 116,090 BTUs per gallon of gasoline or 0.0026¢ per BTU. A better way to look at it is in terms of cost per million BTUs, since a full twenty gallon gasoline tank contains over 2 million BTUs.

In that case, one million BTUs costs about $26.00, whether you are purchasing gasoline, diesel, methanol or ethanol. At 20 miles per gallon of gasoline, you’ll burn about 5,800 BTUs per mile. In a future post: Flexible Fuel Vehicles – The Engine.