Fuel-Efficient Engines are the Jedi Way

MIT scientist John Heywood “has been described as the Yoda of the car engine,” according to the Boston Globe. And if that’s not enough to make you want to know more about this guy (in which case we’re pretty sure you suffer from some kind of curiosity deficit disorder), perhaps his latest project will be.

Heywood and a few other MIT scientists have spent the past few years quietly perfecting an “ethanol-boosted car engine” that uses mostly conventional gasoline, but also gets a little kick from an injection of ethanol. The result? An engine that’s 25 percent more fuel efficient—and uses technology that already exists.

As for how the idea works—well for those of us who don’t spend a whole lot of time thinking about combustion engines, it’s a little complicated. But the Globe has a pretty clear explanation. Bear with us for two long-ish paragraphs:

Here is how the idea works: In a typical car engine, gasoline vapor mixes with air inside the cylinders. Spark plugs ignite the vapor. The tiny explosions drive the pistons down, and the crankshaft converts the pistons’ work into rotational motion. And the car moves, though somewhat inefficiently. When the temperature in a cylinder gets too high, vapors explode spontaneously, instead of burning steadily. Energy burns faster under these conditions. The pressure rises, and the cylinder vibrates, causing what’s known as “knock,” a condition that both impedes and harms the engine. To avoid it, automakers are forced to build cars with lower compression ratios – in other words, they get less energy out of the air and fuel being compressed in the cylinders.

The key, at least according to the MIT scientists, is lowering the temperature inside the engine, and that’s where the ethanol comes in. When vaporized, ethanol absorbs more than twice as much heat as gasoline. Injecting it directly into the cylinders, therefore, has a cooling effect – something automakers have tried to obtain with other fluids, including water. Water does indeed help lower temperatures. But it also degrades the fuel mixture, Bromberg says. Ethanol doesn’t. Bromberg’s models show that temperatures drop by almost 200 degrees Fahrenheit under these conditions. Knock, at that point, is no longer an issue. Compression ratios could be raised. Cars could become more efficient, and, with turbocharging – a process that allows engines to push more air into the cylinders – they’d be more powerful while using smaller engines. Six cylinders, or even four, could do the job of eight. Ethanol-boosted cars could be 25 percent more efficient than cars on the road today, Heywood says, and about 15 percent more efficient than cars rolling out in the next few years. Using less gasoline would mean greenhouse-gas emissions would fall. And because the technology already exists – direct-injection gasoline engines are on highways today – making new cars with the ethanol-boosted engine would be a relatively inexpensive change. The scientists say their idea is not only greener than clean diesel, it’s about $2,000 to $2,500 cheaper to build. And cheaper than a hybrid, too. Think two-thirds the benefit at one-third the cost.

Okay car-engine Yoda, you’ve got our attention. We like the immediacy of this technology, since we all know by now that the key to fighting climate change is slashing our emissions—pronto. But if everyone were to use ethanol-boosted engines, we’re pretty sure we’d still need to find a tenable way to produce the biofuel—something we should be doing anyway. We wonder what Heywood has to say about all this. We’re really hoping it’s “Do or do not, there is no try.”


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where have you guys been
nerding away the hours
turbo inter-cooler diesel cars are driven all over the world except in Gringolandia (USA).
They get much much better mileage. Diesel is NOT flammable
and the turbo gets them over the 10,000 mountains
efficiently and quickly. And contrary
to what Detroit and their lobbyists
are paid to say this is a clean technology. The third world is not the third world. Costa Rica is the first country to have a NATIONAL POLICY
as carbon neutral. They are also moving quickly to this policy, of course, they have a head start. They
have no coal plants, no nukes and
no pollution producing energy plants.
How do they generate electricity?
Hydro and Geo-thermal. Oh yea, a
typical electrical bill in CR is about
$12 a month.
You guys ought to get out of your bubbles and move around the planet.
Creating an economy on corn is a joke.
There is not enough land on our mother earth to grow the amount of corn necessary to fuel an economy based on ethanol.
Let's move NOW to solar/bio-mass and hydrogen cells. Forget the corn, the soy and the palm oil stuff. We can
do bio-diesel only as a ill fit bandaide.
Gaia (earth) will heal - with or without humanity.
Forget Earth Day, a one day a year event - Earth Century is
our only shot NOW.

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