Soil Lamp by Marie Kestaps

The Soil Lamp!  This awesome lamp runs entirely off mud.  The metabolism of biological life creates enough electricity to keep a LED lamp burning forever and ever, all you need to do is add a splash of water now and again.  The mud is held in cells which hold copper and zinc, the dissimilar meters corrode together, generating a current of electricity.  This is a fantastic idea, I wonder how possible it is to produce this type of electricity in large quantities?