BioFuel

[Ispaced]

Does anyone know of any links on this subject, seems I've found some info
on this somewhere. I think it had a link on how to make your own.
Thanks much!

[DonPMitchell]

If you want to read something that is actually scientific, look at the Dec 7, 2006 issue of Nature.  Biofuel is the cover article.

[Satanic Mechanic]

Making Bio-Diesel is easy.  When I worked on hybrid/electric cars there was another team devoted to making bio-diesel, the process is pretty straight forward.  They would combine rapeseed oil with regular diesel and the exhaust smelled like buttered popcorn.
Here are some links I have:
http://www.knowledgerush.com/kr/encyclopedia/How_to_make_Biodiesel
http://journeytoforever.org/biodiesel_make.html

Some of my friends have diesel trucks and wanted to build a bio-diesel reactor to make the fuel when the prices skyrocketed. Remember that this will be a long term investment.  When three of my friends figured the costs, they would see the fuel savings after two to three years.  Depending how much you drive, you will might see the savings after five to seven years.

SM

[Johno]

Since you've worked on hybrids, SM, I was wondering if you could answer a question for me.

I have noticed that the hybrids I have seen basically use a small petrol motor with auxillary electric motors (please correct me if I'm wrong).  From a basic (admittedly high-school only) understanding of physics, this seems to be an inherently inefficient way of doing things.  Am I missing something to think that the most efficient way of doing things would be to have a tiny petrol motor running a generator and have the whole thing work off electricity?

Obviously the people working on these cars aren't stupid, so what have I missed?

[Ispaced]

The bio-diesel page I looked over didn't have a cost effective stat,
That would make a difference. I'll have to add that to the list thanks!
Glactus might be able to find this info, if you don't mind, you know the
site I got the link from.

[Satanic Mechanic]

Since you've worked on hybrids, SM, I was wondering if you could answer a question for me.

I have noticed that the hybrids I have seen basically use a small petrol motor with auxiliary electric motors (please correct me if I'm wrong).  From a basic (admittedly high-school only) understanding of physics, this seems to be an inherently inefficient way of doing things.  Am I missing something to think that the most efficient way of doing things would be to have a tiny petrol motor running a generator and have the whole thing work off electricity?

Obviously the people working on these cars aren't stupid, so what have I missed?

It is a good question Johno. 
There are two types of hybrids- Series and Parallel.  Let me give you the definitions:
A Series Hybrid uses both batteries and the APU (Auxiliary Power Unit) or engine tied to the same bus to supply power.  The car can be ran off batteries alone.  If the batteries start getting low, the APU kicks in to deliver power to the motor/controller and charges up the batteries in the process.  The batteries are acting like a buffer.  If the car is going up a steep grade, we would use both APU and batts.
A Parallel Hybrid has both the batteries and engine separate from each other that power the electric motor.  They switch off between the two.
The hybrid cars that you are seeing on the streets are by my definition- very weak Parallel Hybrids.  They have batteries but they are so small that they are more like Ultra Capacitors than batteries.  They really just supply a boost for acceleration when stopped.
The hybrid that I worked on was a Series hybrid.  We had a 20HP Kohler engine that ran off of gasoline that turned a 10kw generator.  It was tied to together with a battery pack that was 336 Volts.  We then sent the power to the motor controller inverter, turned it into AC to power the motor.  An AC motor was used because it was 95% efficient (electricity to motor shaft).  The AC motor we used to go up to 200 HP or 150kw.

Answer your questions?

SM

[Satanic Mechanic]

Johno, I will let SM answer this more totally.

I believed that the small petrol engine was designed just to get the vehicle moving and when the wheels were turning, the generators in the wheel hubs would provide the voltage for the main electric motor.

Anyhow, I understand that is the principal of an electric hybrid.


Glactus

I use to get this question all the time.  No, you cannot stick generators on the tires to create electricity, you cannot create or destory energy.  You do not get more than what you put in.
We do use regenerative braking or "Regen" as we called it, to charge up the batteries though.  When we brake, we turn the motor into a generator but this is only for braking purposes.

SM

[Satanic Mechanic]

Johno,
Funny you should bring up the hybrids yesterday.  I was watching "Modern Marvels" on the History Channel and there was a story about what people are doing with the Toyota Prius.  Remember I told you about how small the batteries are?  One company is making kits to convert your Prius into a true Hybrid.  A plug in Hybrid.
The kits remove the old batteries with gel cells, the kind I use, and they change out a section of the unibody in the rear to store the larger batteries.  The car mostly runs as a straight E.V. (Electric Vehicle) and it plugs into any 120v socket.
The average commute for an American is about 15 miles and an E.V. is perfect for that.

SM

[evancise]

The average commute for an American is about 15 miles and an E.V. is perfect for that.

I drive about 1.5 miles to work and 1.5 miles home every day.  If they weren't so darn expensive, an EV would be perfect!  I've put 32,000 miles on this car in the 5 years we've owned it - and that includes a trip from Houston to Long Island and back (~4500 miles).

[LunarOrbit]

How durable are electric cars? I assume that internal combustion engines take more of a beating than electric motors, so does that mean electric vehicles can be driven longer before they kick the bucket? Obviously things like tires and shock absorbers will still need to be replaced at the same rate, but the engine itself must last longer, right? If I'm right then we could be building cars that not only pollute less but also don't end up in landfills as quickly.

[Satanic Mechanic]

How durable are electric cars? I assume that internal combustion engines take more of a beating than electric motors, so does that mean electric vehicles can be driven longer before they kick the bucket? Obviously things like tires and shock absorbers will still need to be replaced at the same rate, but the engine itself must last longer, right? If I'm right then we could be building cars that not only pollute less but also don't end up in landfills as quickly.

There is only one moving part, the electric motor.  That lasts for a long time.  My own E.V., I used the existing transmission and bought a spacer, mounting plate and hub to combine the motor/transmission.  It works just like a standard transmission car.  The flexplate/clutchplate/pressureplate connects to the hub which is fastened onto the shaft of the motor.
I need to buy new batts for my E.V., they only last 4 to 5 years.

SM

[Satanic Mechanic]

If I'm right then we could be building cars that not only pollute less but also don't end up in landfills as quickly.

Actually cars are recycled.  Especially now since China is buying up all the scrap metal.  The cost of scrap metal is at its highest in 25 years.
My friends own a wrecking yard so I do not have pay to get rid of derby cars. The government has passed a rule saying wrecking yards need to pay to get certification to crush cars.  So, my friends are now going out of business because of that.  It is a small side business and not there main source of income.  I will miss it though.  It is fun going through old cars and other junk.

SM

[ijuin]

I have noticed that the hybrids I have seen basically use a small petrol motor with auxillary electric motors (please correct me if I'm wrong).  From a basic (admittedly high-school only) understanding of physics, this seems to be an inherently inefficient way of doing things.  Am I missing something to think that the most efficient way of doing things would be to have a tiny petrol motor running a generator and have the whole thing work off electricity?

Obviously the people working on these cars aren't stupid, so what have I missed?

Converting the petrol motor's motion into electricity and then back into motion again is not a 100% efficient process--you lose ten to twenty percent with each time you convert between motion and electricity--this loss can only be avoided if you used superconductive materials, which would either be prohibitively expensive (for high-temperature superconductors), or would require refrigeration that would cost more energy to run than the superconductivity would save you (for cryogenic superconductors). Thus, you get more power by applying the petrol motor's motion directly to the wheels.

[Johno]

Ijuin,

The following information comes from hazy memories of Year 12 physics, and may be out of date or simply incorrect.  But this is the basis for my idea

The transfer of energy from petrol to motion was something like 25 -35% efficient.  The transfer in a generator was in the order of 60 -70%(although if you could use a jet APU, I believe that's in the low nineties!), and an electric motor about 80%.  So if these figures are right, you could expect to have a more efficient conversion in a hybrid.

Plus, you get other fuel savings in the simple fact that an engine driving a generator need not be terribly large to provide enough energy to drive an electric motor.

Incidentally, my Dad thought of something - shock absorbers are another area (like brakes) where you are trying to scrub away waste energy.  The idea of regenerative braking got him to thinking - could you use the shock absorbers to drive a pump, say, for an air conditioner?

[DonPMitchell]

Yes, and I think Johno is being conservative about how inefficient it is to do power conversion (of any form).

The gasoline piston engine is not the most efficient engine unfortunately.  Diesel is better.  Turbine engines are even better still.  A few decades ago American auto makers (mainly Chrysler) did a lot of research on engine design.  The found that turbines require transmission systems that are just too complex and expensive, but they did make a lot of improvements to the piston engine -- mostly marketed by the Japanese before the US ironically (hemispherical heads, etc).

So I question the efficiency of pure electric cars, mostly because I think conversion and transmission of electricity is so inefficient to begin with.

If we had it to do over again, we might look at the hydrogren economy.  Using H2 instead of electricity as the common carrier of power.  It can be more efficiently transmitted, it can be stored, and it can be used directly in portable engines such as  in cars.