Dan Clemmensen wrote:
> Max M wrote:
> >
> > What most of this solar cell discussion really seem to strand on is the
> > energy storage. Has anybody got any knowledge about how the state of affairs
> > is these days concerning decentralised energy storage. Batteries, fuel
> > cells, etc?
> >
> IMO by the time we have replicators, we can consider the biological model
> for solar energy storage: plants store a lot of energy in a distributed
> manner. I'm pretty sure that the energy density of biochemical storage
> greatly exceeds the energy storage in a battery. For example, an adult
> human, at rest, has a heat output of about 125 watts. This human needs
> less than 1700 food calories per day to sustain this. (This is from
> memory, not from a reference book, so I could be wrong.) Looking
> at my cereal boxes, this appears to be about half a pound of
> cereal. I think a nanotech-based device that stores energy like a
> leaf will permit fairly dense distributed energy storage.
Food calories, as I recall, are actually kilocalories in energy terms. As for dense distributed storeage, a maple tree's leaves are only the energy generators in the organism. Several hundred pounds of leaves produce 100-300 calories worth of sap per day, which is stored in the trunk and roots. The total mass of a whole maple tree is several thousand pounds. I would hardly call this a dense distributed energy storeage system. The total surface area of the leaves is several thousand square meters, indicating to me that the energy conversion efficiency of these organisms is far less than 1%
Nano tech organisms should not be designed with their own power generation devices, as that is a prescription for loss of control and catastrophe. Any nanotech we deploy should be entirely dependent upon an outside source of energy, a food, that we supply.
Mike Lorrey