Apple has filed two patents for fuel-cell battery systems which it says will make its Mac Books go for weeks without a recharge.

Two patents with the US Patent and Trademark Office are for hydrogen fuel-cell batteries which will be a lot more environmentally-friendly. The patent suggests that the batteries would be more ecological but could also last “for days or even weeks” on a single charge.

Ecological is important when you partners in China have been told off for polluting land and causing cancer. According to the filing, Apple is investigating a number of types of fuel cells. Hydrogen fuel-cells are the kind most often found in cars, but Apple points out in the filing that building a hydrogen fuel-cell system that can fit into a laptop is quite a challenge.

It has not indicated how it will do it so it could be pie in the sky stuff.