Ralph Merkle, Robert Freitas and others have a theoretical design for a molecular mechanical computer that would be 100 billion times more energy efficient than the most energy efficient conventional green supercomputer. Removing the need for gears, clutches, switches, springs makes the design easier to build.
Existing designs for mechanical computing can be vastly improved upon in terms of the number of parts required to implement a complete computational system.
Ref: Molecular Mechanical Computing Systems. Institute for Molecular Manufacturing (April 2016) | Report No. 46 (PDF)
It has long been known that, in theory, computing processes can be made arbitrarily energy-efficient. The power and heat problems which plague current computers stem from the use of inefficient computing elements (e.g., electronic transistors), not fundamental principles of physics (which indicate that computations can take essentially zero energy).
While essentially all modern computers are electronic, computers can also be implemented mechanically. Power consumption in electronic computers versus mechanical computers stem from fundamentally different phenomenon. Power consumption in an electronic computer is proportional to electrical resistance, while power consumption in a mechanical computer is proportional to friction.
A new design paradigm for mechanical computers has been created which not only vastly simplifies the design of mechanical computers, but relies solely upon mechanisms with very low friction. An analysis of the potential capabilities of a mechanical computer based on this new design paradigm shows that, in a properly designed molecular-scale mechanical computer, friction consumes far less energy than electrical resistance. As a consequence, a mechanical computer designed as described herein has the potential to provide 1012 GFLOPS/Watt, over 1011 times more efficient than conventional “green” supercomputers, which currently provide about 7 GFLOPS/Watt.