Future Fuels

[jamesqf]

Originally Posted by Big Dave

But theres no point in talking about diesels. Tier II/ULSD/ CA ban have pretty much killed diesel cars in the US.

But if you're looking for best fuel economy, you need to scrap both diesel and gas IC engines eventually, and go to a Stirling-engined PHEV system. The electric system provides primary drive, and the starting torque & immediate startup that Stirlings don't have, while the Stirling engine turns fuel into power in the most thermodynamically-efficient way possible for a heat engine.

Though of course the ultimate would be a fuel cell that runs on biofuel of some sort. I seem to remember an alcohol-fueled one, and don't offhand see why it shouldn't be possible to run one on sugar.

And in fact it seems to be possible: http://arstechnica.com/news.ars/post...lly-sweet.html

[Big Dave]

I've heard about Stirling engines for forty years and through numerous oil blips. It simply won't ever power a car. It, and its attendant condensers and pollution-control equiupment are simply too large for the power produced.

Unfortunately Stirlings are like Crower's six stroker - interesting but with massive show-stopping problems.

[jamesqf]

Originally Posted by Big Dave

IIt simply won't ever power a car. It, and its attendant condensers and pollution-control equiupment are simply too large for the power produced.

Funny you should say that, since GM had the prototype Stir-lec, a Stirling-powered hybrid, running back in 1969.

Condensers are no more of a problem than radiators are for IC engines. As for pollution control, it is one heck of a lot easier to clean up a steady-state flame burning at ambient pressure, than it is to deal with all the byproducts of IC engine combustion.

[sickpuppy318]

It seems that it is because biodiesel is low is sulfer that it has major drawbacks, and that the new ULSD has many of the same unwanted qualities as biodiesel.

If the new regs put diesel on its death-bed, they made it easier for biodiesel.

If all our commercial trucks went to B50 it would be a good start.
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Press Release: ETHANOL, LOW SULFUR DIESEL & BIODIESEL:THE GOOD, THE BAD & SOLUTIONS FOR MARINE ENGINES
Low and Ultra-Low Sulfur Diesel: EPA regulations will require many marinas to sell low sulfur diesel by October 1, 2007, though many will make the transition early this summer. Nessenson said, "Low sulfur (500 ppm) or ultra-low sulfur (15 ppm) diesel contain more moisture, destabilize very quickly and are more susceptible to bacterial growth than high sulfur diesel. The results are sludge and plugged fuel filters that can completely shut your engine down while at sea."

Because sulfur helped to lubricate the fuel system, premature injector and fuel pump wear may develop. Older diesels may experience leakage from injector and fuel pump seals that aren't compatible with lower sulfur diesel fuels. Nessenson suggests, "Boaters should keep in mind that fuel additives don't prevent or correct leaky seal problems caused by lower sulfur diesel fuel. They should contact their engine manufacturer to determine if replacement of fuel system seals are necessary.


"We have formulated ValvTect Marine Premium Diesel with BioGuard biocide, lubricity improver, water dispersant, corrosion inhibitor and fuel stabilizer to prevent problems caused by the reduced sulfur content. ValvTect Marine Premium Diesel requires no additional fuel additives, thus eliminating the risk of using the wrong fuel additives, saving time and a lot of money," he said.

Biodiesel: This eco-friendly fuel is becoming popular, especially in the Midwest where tax incentives make the price very attractive. Although biodiesel has good lubrication qualities and a more pleasant smell, it has some of the same problems for boaters as ultra-low sulfur diesel. These include very poor stability and susceptibility to bacteria growth. Biodiesel also contains about 3% less Btu (energy content) than diesel fuel, which causes somewhat reduced power and increased fuel consumption.
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[Big Dave]

It's not that biodiesel's lubrication characteristics are bad. Biodiesel's problems are as follows:

1. It clouds (turns to Jell-o) at 35 degrees F.

2. It costs way more than dino-diesel.

3.The feedstock is food or something grown on arable land with fresh water that could be used to grow food.

Now,if algal bio-diesel can be made to work well the third problem goes away.

4. The EPA hates diesels and bio-diesel cannot be used in spark-ignition engines.