Sunday, 5 April 2020

Notes from "The Knowledge" by Lewis Dartnell

Some notes from "The Knowledge - How to rebuild our world after an apocalypse" by Lewis Dartnell.

This book guides the reader through some of the key technologies that a society may want to rebuild after some catacysmic event (such as a new, highly contagious, high mortality, long incubation, avain flu) has quickly killed a large proportion of the worlds population but left the planets infrastructure largely intact, if inoperative.

The Knowledge by Lewis Dartnell

Dartnell uses the book to conduct a thought experiment considering how a small surviving society could "reboot" itself to quickly recover key skills and technologies to improve food yields, reduce manual labour and increase health. THe book covers many areas ranging from medicine to electricity, communications, transport, mechanisation, explosives and power generation.

But easily the most fascinating aspect of the book is the way it describes how, from first principles, a society can source the basic chemicals and processes to keep themselves healthy, fed and housed. The chemistries that seemed particularly interesting are briefly described below, with some added linkage:

DISCLAIMER : For the love of God, do not use this post as an instruction manual. Many steps or details are omitted, many processes and chemicals are dangerous.

Water Filtration : Bucket with small holes in the bottom and a layer of charcoal, covered with alternating layers fine sand and gravel

Water Purification : Few drops of 5% bleach solution (sodium hypochlorite) will disinfect a litre of water in an hour. Or use a SODIS approach by placing 2litre pop bottles full of water in sunlight for 6hrs (if bright) to a couple of days (if overcast).

Human Manure as a fertilizier for farming : If compost is kept in an airtight environment, anaerobid bacteria thrive and produce methane gas, which can be collected in a basic "gas tower". This technique was employed a lot in occupied Europe during WW2, when fuel supplies were disrupted.

Productivity : In 1850, the UK had the most productive agriculture in the world, with just one person in five working the fields, by 1880 is was 1 in 7; by 1910 it was 1 in 11 and today industrialised nations typically have just 1 in 50 involved directly in agriculture, leaving the other 49 free to perform other tasks in science, medicine, engineering and other aspects of society.

Yeast : Make a mix of 1:2 by volume mix of flour and water, cover and place in a warm location. Once it starts to froth throw half away and add more flour/water mix, repeating twice a day for a week. By the end you should have a culture of lactobacillus bacteria (who break down the flour) and yeast who live on the breakdown by products, releasing CO2 gas and lactic acid (which inhibits growth of competing organisms).

Sourdough starter (source)

Ethanol : If a suitable yeast culture is in an air resticted environment, the yeast can only partially decompose the sugars, instead releasing ethanol, which can be purified by distillation (yeast by itself cat break down starch so instead of flour, whole grains need to be allowed to germinate and convert the starch to sugars.).

Acetic Acid (Vinegar) : Expose ethanol to the air and bacteria will convert the ethanol to acetic acid.

Canning : fill glass jars with food, seal and heat for a few hrs to kill bacteria.

Cooling : Zeer pots are used in Africa.

Refrigeration : It is purely a historical accident that household fridges need electricity to drive a compressor. It is perectly possible to use the approach taken in an "absorption refrigerator", in which the refrigerating is dissolved into, and then evaporated from, a second fluid insted. Such refrigerators can work wiithout electricity if they can use the heat of the sun for the evaporation phase.

EROEI : The "Energy Return On Energy Investment", a measure of how much energy has to be used to get to a fuel source such as oil or coal. Early Texas oilfields had a EROEI of ~100 meaning that 100units of energy were extracted for every 1 unit used in drilling. Today, the EROEI is around 10, showing how all the easily accessbible sources have long gone.

Charcoal : Almost completely seal an amount of wood then set it on fire so that it smoulders over a period of day, under careful monitoring (link) . This carbonises the wood and drives off moisture and and volatile compounds. Charcoal burns hotter and cleaner than coal.

19th Century Charcoal Oven (Source)

Acetic Acid(Vinegar) , Acetone, Methanol : All of these can be distilled from the watery condensate of charcoal burning process.

Creosote, Pitch, Turpentine : All of these can be distilled from the tarry condensate of the charcoal buning process.

Coke: Carbonised coal, using a similar process to Charcoal, above.

Candles : Boil animal fat in satly water and skim of the fatty floating layer into a container and then repeatedly dip the candle wick into it.

Quicklime (Burnt Lime, Calcium Oxide) : Burn limestone (Calcium Carbonate) in a kiln at 900C.

Slaked Lime (Hydrated Lime, Calcium Hydroxide) : Mix quicklime with some water, producing an exothermic reaction and giving a Calcium hydroxide precipitate putty.

Potash (Potassium Carbonate) : Tthe dry white ashes of a wood fire and place in water. Disgard the material that floats or sediment and take the water (with its dissolved material from the ashes) and dry off. The resulting white powder material is Potash. You will get about 1g of potash for every 1kg of wood burnt.

Soda Ash (Sodium Carbonate) : As for Potash, but using seaweed for the fire.

Caustic Soda (Lye) : React Slaked Lime with Potash or Soda Ash to give Caustic Potash (Potassium Hydroide) or Caustic Soda (Sodium Hydroxide).

Caustic Soda granules (source)

Soap : Need to break the glycerol- fatty acid bonds in fat (saponification) with an alkali so that the fatty aids are free - these are the molecules that have the key ability to lock onto dirt and fat and yet stay dissolved in water. This can be done by putting some Potash or Soda Ash, or (preferably) Caustic Soda into a vat of boiling fat.

Glycerol : If the soap is dissolved in water and salt added, the fatty acids with precipitate out, leaving the glycerol in solution.

Chlorine gas : Electrolysis of brine.

Sulphur Dioxide gas : Can be baked out of common pyrite (sulphide containing) rocks.

Sulphuric Acid : React Chlorine and Sulphur Dioxide gases with activated (very porous) charcoal to produce sulphuryl chloride, which breaks down in water to form Sulphuric Acid and Hydrogen Chloride gas.

Hydrochloric Acid : Collect the Hydrogen Chloride gas from the manufacture of Sulphuric Acid and dissolve in water. Or react Sulphuric Acid with Sodium Chloride (table salt).

Nitric Acid : Reaction of Suphuric Acid with saltpetre(Potassium Nitrate), which can be mined or made from first principles.

Bricks : Form and heat clay (mined from clay beds) to 900C so that the aluminosilicate particles fuse and a waterproof material.

Lime Mortar : Slaked Lime (see above) mixed with sand and water.

Concrete : Lime Mortar mixed with stones or other aggregates.

Glass : Sodalime glass (which is what is often made today) is made of sand, soda ash (to reduce the melting temperature) and quicklime (which makes the glass insoluble in water), all heated to a high temperature in a kiln.

Ammonia : Can be produced by fermenting urine.

Nitrous Oxide : This pain reliever can be made by reacting ammonia and nitric acid to produce Ammonium Nitrate, which can then be heated to produce Nitrous Oxide.

Ether (Diethyl ether) : This anaesthetic can be produced by reacting ethanol with sulphuric acid and then distilling off the ether.

Dartnell also comments briefly on the other conditions required for industrialisation, suggesting the it was the combination of high wages, low interest rates and abundant energy that resulted in the wholesale industrialisation of the UK by encouraging labout to be substituted by machinery. In contrast, although China invented many of the technologies centuries earlier, there was not the same incentive to move away from labour intensive methods.