Learn me: How are "standard hybrids" more efficient?

EastCoastMojo wrote: Regenerative brakes? So you never have to replace the brake pads?!

119k on our Prius. Still on the original brake pads and PLENTY of meat left. It's odd.

wvumtnbkr wrote: I actually did account for regen. Is it really that large of a payback? I also specifically did not talk about plug-in type hybrids (like the Volt) That is another ball of wax. As far as the decel and idling goes... I was under the impression that a newer car under deceleration does not inject fuel. (Why would it?) A lot of newer ICE powered cars also have a stop start feature. I am gaining knowledge here, but I am not convinced yet....

Yes, the recovery of energy during slowing down is really significant- by a wide margin, it's the carrot of all carrots for hybrids. But also be aware that for most combusiton engines, they are more efficient at making cruising power + regen power than they are at accleration power- so there IS a net benefit to charging the batteries during a cruise, and using that to accelerate the next time.

Turning the car off during decels is old had- and stopping the engine during idle is becoming more and more common- but those are the low hanging fruit in terms of CO2 production on an FTP. The rest is pretty evenly split between psudo steady state (more about drag) and accelerating (weight + energy recovery).

(variable displacement comes and goes. not sure if it will be across the board- I know work on it was heavy here in the early 90's)

As for the engine cycle- yes- most hybrids use Atkinson, since is pretty easy to turn a robost Otto into an Atkinson. And relatively speaking, piston engines are really cheap.

In terms of gasious emissions- most hybrids are also PZEV- which gives them extra credits in terms of high tech. But there are a LOT of cars out there that are also PZEV. So hybrids are not the only ones that are quite good for the air quality. Which actually brings up a whole different thread about PZEVs and comparing that to energy production for electric cars- i'll leave it at- PZEV's actually replaced California's EV mandate, since it's original point was to clean the air.

hybrids are one of many ideas for the future. And a basic ICE with nothing else will remain on the table for quite some time. Unless there's a pretty major development that uses iron and aluminum for a power plant, and stores energy like long chain HC's do- well, you know.

Thanks all for the info!

I guess the regen wins!

For E36 M3s and giggles, what about a regen system for an ICE powered car that spins a flywheel that can be tapped into the drive system (Is that how KERS works?) to produce a boost?

Would that eliminate the batteries and motor (but require a heavy flywheel) and get the same benefits of the hybrid?

wvumtnbkr wrote: Thanks all for the info! I guess the regen wins! For E36 M3s and giggles, what about a regen system for an ICE powered car that spins a flywheel that can be tapped into the drive system (Is that how KERS works?) to produce a boost? Would that eliminate the batteries and motor (but require a heavy flywheel) and get the same benefits of the hybrid?

A few ideas have been tested, the most notable being compressed air. None of them really panned out. I remember a Chrysler project that was going to use flywheels for a LeMans project- never saw that it moved. F1 kers uses electricity with a battery pack.

But the system that Honda used with it's original hybrid was pretty close- it used kind of a charged flywheel, or motor/generator, which was quite simple and straight forward. It's problem is lack of "coolness"- it was never to move w/o the engine. It just worked great.

I think people still dream about flywheels- but so far, batteries are winning that decisions pretty easily. I've seen articles about flywheel modules, inside vacuum bubles on super high tech bearings.... Just don't seem to pan out.

WIthout a doubt, if someone can come up with a reasonable cost recovery system that is the same size as a battery, stores the same (very limited energy), and can be stored and recovered just as fast- people will jump all over it. There's a pretty good opportunity there, if you ask me.

wvumtnbkr wrote: For E36 M3s and giggles, what about a regen system for an ICE powered car that spins a flywheel that can be tapped into the drive system (Is that how KERS works?) to produce a boost? Would that eliminate the batteries and motor (but require a heavy flywheel) and get the same benefits of the hybrid?

It's been tried in race cars, the problem is that a "charged" flywheel of meaningful capacity is also a large, very dangerous kinetic bomb, as was found out the hard way. Seen an average car flywheel explode? That's a little pipsqueak compared to one intended for energy storage.

KERS uses batteries, but Porsche recently made a race car that used a small flywheel mounted on a gyroscope (to reduce gyro strain on the wheel) in place of a KERS battery.

Trouble with a flywheel is that you're going to be talking about some sort of mechanical linkage and kinetic storage. You're going to have way more losses than with a battery (both in terms of driveline and entropy). You're probably not going to save much weight since the flywheel will require enough mass to move the car. You'll probably also have tougher packaging issues. If the goal is to store up just enough energy to assist in one or two stops and starts, you're probably better off with just a smaller battery.

Have there been research into replacing/downsizing the belt-driven alternators on regular cars and have the majority of the electrical energy replaced when braking?

Right now it does look like batteries are winning (have won?) the KERS battle, but it didn't look so clear cut as things got rolling. I was really intrigued by the Flybrid flywheel setup (not that my intrigue has any bearing on function). There was some neat tech there.

For all the good it does, my fingers are currently crossed for electrical storage via some development like graphene capacitors. Take this, of course, with the usual grains of salt and make sure to diversify your egg portfolio across a selection of baskets.

How do you store the energy over a longer period of time? When I get in the car in the morning, the battery is still at the charge level I left it at the night before.

In reply to DaveEstey:

Is that re: capacitors?

Honestly, I don't know. Are they necessarily that "leaky"? Do they normally give the impression of being that way due to the normally-tiny amounts of energy they store (i.e. it only takes a tiny dissipation to empty a 1uF cap?)

ransom wrote: Is that re: capacitors? Honestly, I don't know. Are they necessarily that "leaky"? Do they normally give the impression of being that way due to the normally-tiny amounts of energy they store (i.e. it only takes a tiny dissipation to empty a 1uF cap?)

Yes. Capacitors are "leaky". They store energy in electric fields, not chemicals. Typically, they will begin discharging themselves as soon as the current is removed.

If you think of an electrical circuit as being like a circuit of water, a capacitor is like a rubber membrane being pushed on by the flow of water (current). When the flow is released, the capacitor pushes back. It stores potential energy, not chemical energy.

Capacitors are for short term storage, generally to do things like keep an even current by resisting current spikes, and then returning that energy when the current weakens. (This is a gross simplification.)

wvumtnbkr wrote: Thanks all for the info! I guess the regen wins! For E36 M3s and giggles, what about a regen system for an ICE powered car that spins a flywheel that can be tapped into the drive system (Is that how KERS works?) to produce a boost? Would that eliminate the batteries and motor (but require a heavy flywheel) and get the same benefits of the hybrid?

There are a number of trucks using a hydraulic system to capture and store energy.

..."The hydraulic hybrid system gets its power through regenerative braking. That means that, flying down the highway, a hydraulic hybrid isn't much different than a regular car. But in traffic, particularly stop and go traffic, a series hydraulic hybrid can shut its engine off and use hydraulic power alone. Stopping and starting is the key to saving fuel with a hydraulic hybrid.

UPS trucks go from one stop to the next, often in urban traffic, and are rarely used on the highway. They're also often left on as drivers make pickups and deliveries. In conventional UPS trucks, this creates pollution and adds to the company's fuel costs. However, in the series hydraulic hybrid trucks, the engine can shut off while the truck is on."

http://auto.howstuffworks.com/hydraulic-hybrid3.htm

In reply to Wally: Citroen shoehorned a system similair that is similair in theory to this into their C3 and plans to put it into production shortly. I think that this is more promising than electric hybrids.

In reply to Beer Baron:

I get the distinction (my grasp of electronics is way worse than anybody who does it for a living, but better than man-in-the-street, more or less), but that doesn't explain why for a given amount of stored energy a capacitor would leak it where a battery would not.

I found this, which may or not be a good source, but seems to indicate that the losses are where you would expect them to be; across the plates and through the terminals. The through-the-terminals path would apply to batteries as well, so this seems like one of those scaling items (i.e. we're used to thinking of caps sized to filter noise on a circuit, not store energy which is the purpose of the advancements in supercapactors, so a small leak will empty them quickly) that isn't necessarily a problem for huge caps. The leak across the plates, though... It sounds like without the development of better dielectric material, that this would continue to apply. I don't know what research, if any, is being done into this aspect of caps. I also don't know if you had a bank of graphene caps large enough to power a car for 50 miles whether it would dissipate 5, 10, or 90 percent of its charge overnight. At this point, I suspect the researchers don't know, either, as the makeup of the graphene caps is still changing...

I just read the title as "stanced hybrids", I think I need a nap.

DaveEstey wrote: How do you store the energy over a longer period of time? When I get in the car in the morning, the battery is still at the charge level I left it at the night before.

Another awesome question.

Here's an idea- find a chemical that one can transform to store energy. But I don't know of a reversable chemical reaction, outside of batteries....