Previously, we noted the use of ultracapacitors in hybrid propulsion. Now MIT laboratories are announcing that they can improve ultracapacitors by swapping in carbon nanotubes, thereby greatly increasing the surface area of electrodes and the ability to store energy. Ultracapacitors, a souped-up version of the capacitors widely used in electronics, have been around for decades. They're well-known for being powerful, that is, able to quickly absorb and release electricity. But they can't store much energy so their stored electricity is depleted in a matter of seconds. As a result, they've been limited to niche applications, such as providing quick bursts of power in some hybrid transit buses. Now researchers at MIT have found what they believe is a way to improve the endurance of ultracapacitors several-fold -- allowing the devices to retain the power and longevity advantages, while storing about as much energy as the batteries used in hybrids.