Unfortunately, as hwillis explains in another comment (https://news.ycombinator.com/item?id=13779143 https://news.ycombinator.com/item?id=13779143), it's not 3x

Unfortunately, as hwillis explains in another comment (https://news.ycombinator.com/item?id=13779143 https://news.ycombinator.com/item?id=13779143), it's not 3x energy for the same weight, it's 3x energy for the same size. It seems to actually be about 2.5x heavier for the same energy.