DMM energy products
From Wise Nano
Diamondoid/fullerene molecular manufacturing promises to build very high-performance products direct from blueprints. But how does this tie in to the real-world energy infrastructure? What products can replace power lines, power plants, gasoline-powered cars, etc?
Desired scenario: Joe Homeowner hires an installer. The installer throws something like a black tarp onto the roof and pushes a button; it unfolds, then attaches itself to the shingles with micro-scale mechanical anchors. A thin wire runs from the tarp to a cubic-foot box that's mounted on the wall near the electric meter. This is the energy storage unit, sufficient to run the house for a few days. The storage unit feeds into the house's power supply, and also sells excess power to the grid, just as advanced solar installations do today. Installation takes about an hour; the installer's training took only a month.
Joe's car has been retrofitted. The fuel tank has been disconnected and drained. The space under the hood has been filled with a motor and brace connecting to the driveshaft, a storage box like the one on the house, and some water tanks so the car's handling isn't changed too much by the removal of the heavy engine and transmission. Joe can recharge his car from his home power system; a cable about the size of an extension cord can transfer in one minute enough energy to go 400 miles. For a small extra fee, Joe can install an automated system that tops up his car whenever he parks it.
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Solar collectors
Probably the simplest solar collector would be based on thermionic electricity generation. This relies on light concentration to achieve high temperatures, so it requires direct sunlight. But where sunlight is plentiful, thermionics can reach efficiencies of 50%. Holographic lenses can be very thin. CVD diamond thermionics have been demonstrated in the lab.
Photoelectric solar cells would be nice, for diffuse light. Does anyone know how to make them out of buckytube semiconductors?
Power transmission
In theory, a rotating diamond shaft can transfer power at a gigawatt per square centimeter. However, this requires a very high rim speed, which may make bearings inefficient and may require vacuum surroundings. More study is needed. But rotating shafts appear to be potentially very competitive with wires.
Graphene and some buckytubes are excellent conductors of electricity. Diamond is an excellent insulator (2 GV/m).
Power storage
There are lots of options for power storage. Perhaps the simplest is a spring. Buckytubes are strong and tough, and stretching them should be able to store energy at some modest fraction of the energy density of their chemical bonds. (This fraction will increase as they are cooled.) At this level of analysis, flywheels are approximately equivalent to springs.
Compressed-hydrogen tanks may be able to store approximately their weight of hydrogen. In theory, energy can be extracted from the pressure in the gas as well as the combustion of the gas.
However, any system operating close to the limits of energy storage density using momentum (Flywheels) stretched bonds (Springs) or compressed gas, is for all practical purposes a bomb. From a safety perspective, chemical storage where a fuel is synthesized, and the oxidizer extracted from the air, is probably better. And fixed installations do not normally require extremely high density storage.
Power generation and conversion
Nanostructured fuel cells could be quite efficient and cheap to build. Fuel cells beat the Carnot heat-engine efficiency limit.
Nanoscale electrostatic motors should have extremely high power density: scaling laws imply kilowatts per cubic millimeter. These motors also work as generators without modification.
Power switching
Tunneling gaps can change their resistance by orders of magnitude with 1 nm motion.
Mechanical power can be switched with mechanical clutches, etc.
References
Many of these topics are touched on in Nanomedicine chapter 6.
The electrostatic motor is from section 11.7 of Nanosystems.
