Hybrid batteries tease big energy capacity while charging in seconds / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

Hybrid batteries tease big energy capacity while charging in seconds

previous 1 2 3

Move Thread

LAN_403

klugesmith

Thu Nov 18 2010, 09:57PM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

But there's venture capital and government programs working to build an infrastructure.
A logical place to charge commuter cars is at the workplace -- a 240V 30A charging station
can serve more than one user in the course of a day. Check out these maps:

A motorist at the turn of the 20th century would have faced a similarly sparse map,
but could lug around canisters of extra fuel. (The jerrycan had not yet been invented).

Adam Munich

Thu Nov 18 2010, 10:26PM

Registered Member #2893 Joined: Tue Jun 01 2010, 09:25PM
Location: Cali-forn. i. a.
Posts: 2242

I don't think people would be lugging around extra batteries though. Not at a few grand a piece.

The problem we have with lithium ion, and thus the problem we have with electric cars is battery life. Not in the standard sense, but in the lifetime sense. Even the best lithiums have only a few hundred charge cycles, and I'm not so sure people would like to buy a new 2000 something dollar battery pack every two years...

2Spoons

Fri Nov 19 2010, 12:32AM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
Location:
Posts: 615

Lithium batteries reaching over 6000 cycles are in production now. The previous cycle limits of several hundred were with the old anode/cathode technology.

Thats a 10 year lifetime, at ~2 charges per day!

Personally I favour methanol or ethanol fuel cells for EV, as the infrastructure for delivering liquid fuels is already in place, these fuels are easier and safer to handle than hydrogen, production is simple, energy density is very high (better than H if you take the storage method into account).
Probably a fuelcell / battery hybrid is going to work best: the fuel cell only need be large enough for the average power usage, the battery supplies the demand peaks.

klugesmith

Fri Nov 19 2010, 01:20AM

Registered Member #2099 Joined: Wed Apr 29 2009, 12:22AM
Location: Los Altos, California
Posts: 1716

2Spoons wrote ...
Personally I favour methanol or ethanol fuel cells for EV, as the infrastructure for delivering liquid fuels is already in place, these fuels are easier and safer to handle than hydrogen, production is simple, energy density is very high (better than H if you take the storage method into account).

Would be nice, but with today's technology methanol/ethanol are not a very efficient way to -store- energy.
Not counting the sunlight and water to grow crops, I think it still takes more electricity and fossil fuel to produce alcohol than you get back, even by burning the alcohol in a fuel cell instead of a combustion engine.

And the principal feedstock for producing H2 in industrial quantities is still methane. Ask the people who fill the Space Shuttle's fuel tank.

Of course we must crawl before we walk, and walk before we run.

Bjørn

Fri Nov 19 2010, 05:17AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

Here are some points to remember.

Electricity is is available everywhere so you can charge at any time. Even early electric cars have a range that is good enough for most days for most people and can happily charge overnight. A car using the best technology today would have many times the range and charge in less than an hour if needed.
Most car trips are less than 3 km in length, causing combustion engines to run at lower efficiency and with more unpleasant emmisions.
Tracking of cellular phones show that people rarely move more than 10 km from their home.
The 20% efficiecy number for a car is assuming that you move at a constant reasonable speed for a significant time. In large cities where most of the people live that is unrealistic.
Steve Conner can move at 30 km/h on his bike using around 200 W. That is faster than the average traffic speed in large cities (and many small towns) where most people live. The efficiency of a normal car in rush traffic is appalling and is where electric is most efficient.

Not counting the sunlight and water to grow crops, I think it still takes more electricity and fossil fuel to produce alcohol than you get back, even by burning the alcohol in a fuel cell instead of a combustion engine.

There are many possible ways to produce ethanol some methods are very inefficient and is is often used as an example that it takes more energy to make than it cotains. Most of the studies I found using google came to the conclusion that there is a positive gain.

For example the extraction of sugar from sugar canes generates a lot of excess heat that can be used in the destillation process so no energy from the outside is required.

Chris Russell

Fri Nov 19 2010, 09:38AM

... not Russel!
Registered Member #1 Joined: Thu Jan 26 2006, 12:18AM
Location: Tempe, Arizona
Posts: 1052

Yes, I suspected that 20% was a tad too generous. Still, even an order of magnitude or two makes for a pretty ridiculously high amount of power to charge in a few minutes. That doesn't mean that electric cars are in any way unfeasible, it just means they aren't a drop-in replacement for petrol cars. Things will have to change. People will have to get used to the idea that your car gets charged overnight at home, and/or at work. Businesses like shopping centers and parking garages might also make charging stations available for a nominal fee to attract customers. People will also have to get used to the idea that for longer trips by car (which are rare for most), one will need to either rent a petrol car, arrange alternate transportation, or make a lot of potentially lengthy recharge stops.

Ethanol itself does seem to be edging its way fairly nicely into positive territory, which is encouraging news. Internal combustion engines using ethanol, of course, still suffer from all the same disadvantages Bjorn mentioned. An ethanol fuel-cell and electric hybrid, however, could be a tremendous step in the right direction: instant refueling, reasonably long range, all sorts of clever things to recoup energy loss like regenerative braking. It's just a matter of getting the technology ready.

Steve Conner

Fri Nov 19 2010, 10:48AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Yes, it's true, a bike is an incredibly efficient mode of transport. But it's not for everyone. The problem is that the availability of cars has changed the layout of newer cities so that you need cars to get around. Because you can travel by car, you must travel by car. For instance, maybe there are 20 miles of freeway between your home and your workplace, and it's illegal, not to mention insane, to ride a bike on it.

I live in a city that was built before cars were available, and the city council has a reasonable policy on bike lanes and so on, so I manage fine without one. On the contrary, it's the car drivers who have the problem as they struggle through city centre streets that were really meant for horses and buggies.

If I need a car or van for some reason, I rent one. (Yes, there is a car rental place 5 minutes' walk away.)

I didn't ditch my car for ethical reasons. It failed the vehicle inspection, and the work to put it right would have cost twice what the car was worth in working order. I decided that I would just try to hold out as long as possible before getting another one. It's been about 5 years.

Bjorn might have added to his list that he lives in Norway, land of huge mountains, rain, snow, mighty roaring waterfalls, and lots of cheap hydro power. If any country could make electric cars work it would surely be there. Although, there would be something sad about a Tesla Roadster with snow chains.

Bjørn

Fri Nov 19 2010, 02:36PM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

There is alctually a Tesla Roadster down the road somewhere but I have not checked out how it looks on ice. I would assume the far superiour traction control you get with electric drive will make it very driveable on snow and ice. I doubt the rest of the car is very suitable for arctic conditions. Snow chains are extremely rare to see on personal transport, spiked tires works pretty well.

What makes electric cars fairly impractical is the cold, more energy would be spent heating the car than to push it forward. And after the average 2.5 km trip the car is just getting up to themperature and the energy is completely wasted. Cars are not really designed for what they are used for, they are designed for being tested on TV programs by people that have no connection with reality.

Steve Conner

Fri Nov 19 2010, 02:56PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Yes, like this

previous 1 2 3

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob