BERKELEY, Calif. (MarketWatch) -- Anyone who has followed batteries knows the likelihood of a new technology to come along and save the world from itself is close to nil. All we can hope for are tweaks that incrementally improve battery performance. But there is a tweak that interests me, and it should interest investors as well. It's a lithium-titanate battery developed by Altair Nanotechnologies /quotes/comstock/15*!alti/quotes/nls/alti (ALTI 1.10, +0.05, +4.76%) , and it's now being experimented with by the U.K.'s Lightning car company, as well as at least one U.S. carmaker. What makes this battery valuable for automotive use is its...