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« A Special Note to Kiwis | Main | Nukes vs. Wood Fires »

October 31, 2006


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John Acrinoe

It bears mentioning that design for recyclability using molecular manufacturing promises to be very effective.

My personal hope is that nanotechnology products will enable most products to trend toward polymorphic smart materials. Multi-use materials that are never thrown away, just remolded and retasked to whatever the current need may be.

Chris Phoenix, CRN

Polymorphic smart materials certainly have their advantages. An example is Josh Hall's utility fog. But they pay for flexibility with lower performance. IIRC, utility fog has about the density and strength of balsa wood.

Nanoblocks could be seen as an intermediate stage between utility fog and fully monolithic products. Nanoblocks don't reconfigure themselves, but they might be reconfigurable by external means. If so, they would be re-usable. My main concern there is that really strong joints won't be tolerant of contaminants, so again you'd pay for flexibility with performance.


jim moore

There are two main variations on the idea of a nano-factory. In the first variation, the nano-factory is a single machine system that makes complete products from simple chemicals (like acetylene). In this system Chris suggests the simplest solution to what to do with products you want to get rid of is to burn them. You should be able to burn diamondiod products very cleanly but you will generate carbon dioxide. The carbon dioxide can be bubbled through sun lit tubes filled with water and algae and > 80% of the carbon dioxide will become part of the algae. So you can make the “simple feed stock nanofactory “ far more environmentally friendly than today’s manufacturing system.

The second variation on a nano-factory splits the manufacturing into two discrete steps that occur in different locations. The fist step uses simple chemicals to make atomically precise building blocks. The building blocks are then sent out to consumers who use a simple fabricator that assembles the building blocks into a wide variety of products. If you make the building blocks big enough they can be reusable. Chris, in his primitive nano-factory paper, described a system that uses building blocks that are ~0.1 –0.2 microns in length. He did that primarily to make the design of products much easier. Building block of that size will probably be fairly difficult to reuse because of the difficulty in fully removing contaminates from the surface of all those building blocks. But if the building blocks are ~10 – 20 microns in length you have 10,000 times less surface area to clean. Also by increasing the size, every building block can a computer integrated into it. By putting a computer in every building block you make every building block traceable / trackable increasing security and accountability. Also having a computer in every building block can prevent the “Grey Gobbler” problem by requiring a computer “key” to unlock building blocks that have been joined together. (Grey Gobblers are autonomous robots that eat products made of reusable nano-building blocks to make more Grey Gobblers.)

In the two step nano-factory system once you are finished with a product made by your personal fabricator you toss it into a block disassembler. The disassembler provides the product with the “key” that allows it to disassemble the product. The reusable parts are cleaned, sorted, tested, and computers reset to initial settings. The reusable parts are then available to be reused in your personal fabricator.

The second system will use substantially less energy, provides an incentive not to create nano-litter, is substantially less dangerous from a security standpoint, and somewhat less disruptive to the economic system.


What will be the deal on flammability of nanotech products? Would they be safe to use for building materials, for example? Or would they catch on fire and burn at ten million degrees or some such horrific value?


One other point. For everyone in the world to have one of these nanofactories will overwhelm our energy generation capabilities. At 200 kiloWatts, each device consumes 6 billion BTU/year of energy. With one per person, 7 billion people require 40 quintillion BTU per year. Current worldwide energy consumption is about 400 quadrillion BTU so this is 100 times higher. Clearly we cannot expand our installed base of energy generation 100-fold without completely re-engineering our entire energy infrastructure.

It's also worth noting that Robert Freitas once calculated that energy consumption should not go over 100 kW per person or else waste heat generation will start screwing with the Earth's energy balance and changing climate patterns. He estimated that this would limit each person to about 10 kG of active nanotech material at any one time.

Freitas was also skeptical that we could keep a substantial plant population on Earth once we start capturing this much solar energy. Giving each person a nanofactory may mean eliminating forests and replacing them with fields of solar collectors. Maybe they can be made to look like fake trees, like they have at Disneyland. I guess that wouldn't be so bad.

Phillip Huggan

MNTed mirrors are a coarse solution to the waste heat issue. Or MNTed heat pumps channeling waste heat from centralized power stations deep into the lithosphere/mantle, if the idea is engineerable.

Diamond is flameable in oxygen at around 800C. Carbon nanotubes maybe at room temperature in the presence of oxygen, but surely an inert coating can be applied to CNT substrates.

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