waboom
10-01-2009, 08:49 AM
Another interesting one from the web:
Carbon nanotubes may power ultracapacitor car (http://arstechnica.com/science/news/2009/09/carbon-nanotubes-may-power-ultracapacitor-car.ars)
This is a speech given by MIT professor Joel Schindal about using ultracapacitors in transportation in the future. Some interesting highlights from the article:
When Schindal was first at MIT, a capacitor with a capacity of 350 Farads would have taken up the whole stage. Today, a 350 Farad ultracapacitor would be the size of a D battery.
Even with these improvements, ultracapacitors still lag batteries in terms of storage density, holding only 5% of the charge per volume of lithium ion batteries.
The charge cycle of a ultracapacitor is about a million times. As far as Schindal is concerned, that means "they can be recharged indefinately."
He thinks he can do a fivefold increase in storage density for ultracapacitor within the next year using carbon nanotubes, as opposed to activated carbon (he actually says "in a matter of months", but I'll pad his schedule for him.) Even with that increase, he'll only have 25% of of the charge per volume of li-on batteries.
HOWEVER, and this is interesting because I haven't seen this discussed before, he says that currently all-electric cars "are overprovisioned with storage capacity in order to keep the battery operating within a narrow capacity range, which improves its performance and extends its life." So, if you're replacing the battery pack in a car with an ultracapacitor, you can use one with a lower charge capacity than the battery and still get the same performance.
Schindal also touched briefly on our favorite ultracapacitor company, EEStore. He said that the approach EEStore is using could theoretically perform as well as they claim, but remains skeptical of them until they release more information.
The article is also good, in that it talks about the reasons that ultracapacitors are better for electric car use than batteries:
Unlimited recharge cycles without losing charge capacity.
Ultracapacitors allow for rapid discharge for acceleration
They can absorb quick bursts of charge from a regenerative braking system
They can absorb charge quicker and more efficiently than batteries - useful for a lunch-hour charge, for example.
Carbon nanotubes may power ultracapacitor car (http://arstechnica.com/science/news/2009/09/carbon-nanotubes-may-power-ultracapacitor-car.ars)
This is a speech given by MIT professor Joel Schindal about using ultracapacitors in transportation in the future. Some interesting highlights from the article:
When Schindal was first at MIT, a capacitor with a capacity of 350 Farads would have taken up the whole stage. Today, a 350 Farad ultracapacitor would be the size of a D battery.
Even with these improvements, ultracapacitors still lag batteries in terms of storage density, holding only 5% of the charge per volume of lithium ion batteries.
The charge cycle of a ultracapacitor is about a million times. As far as Schindal is concerned, that means "they can be recharged indefinately."
He thinks he can do a fivefold increase in storage density for ultracapacitor within the next year using carbon nanotubes, as opposed to activated carbon (he actually says "in a matter of months", but I'll pad his schedule for him.) Even with that increase, he'll only have 25% of of the charge per volume of li-on batteries.
HOWEVER, and this is interesting because I haven't seen this discussed before, he says that currently all-electric cars "are overprovisioned with storage capacity in order to keep the battery operating within a narrow capacity range, which improves its performance and extends its life." So, if you're replacing the battery pack in a car with an ultracapacitor, you can use one with a lower charge capacity than the battery and still get the same performance.
Schindal also touched briefly on our favorite ultracapacitor company, EEStore. He said that the approach EEStore is using could theoretically perform as well as they claim, but remains skeptical of them until they release more information.
The article is also good, in that it talks about the reasons that ultracapacitors are better for electric car use than batteries:
Unlimited recharge cycles without losing charge capacity.
Ultracapacitors allow for rapid discharge for acceleration
They can absorb quick bursts of charge from a regenerative braking system
They can absorb charge quicker and more efficiently than batteries - useful for a lunch-hour charge, for example.