> So, after all those television-watching Britons go to bed, Dinorwig’s generators are run backwards.<p>> It’s a remarkably efficient process, with about 75% of the energy available for reuse.<p>Not an (hardware) engineer, so wondering: are turbines typically efficient running <i>both</i> ways? Or would a turbine in this scenario have tradeoffs compared to turbines that are designed for running in one direction only?<p>The best I can come up with from the comfort of my armchair is that straight gears are typically equally efficient in either rotating direction, but often gears with angled teeth are used when one rotating direction is primary.