Great Info from ScienceInAfrica

[Koula]

Hi all,

I found some great info produced by a Doctor in Africa, for sustainable fuel production purposes, which I doubt will be online forever, as with many older websites it is often proven that once online does not mean forever available. So in the interest of archiving some useful information, here you go.

http://scienceinafrica.com/old/index.ph ... nmower.htm" onclick="window.open(this.href);return false;" rel="nofollow

Fermenting waste fruit to fuel ethanol

By Dr Garth Cambray

For hundreds of years the lawn around a house represented a sort of fuel tank - you parked your transport - a horse - outside your house and it ate your grass keeping a nice trimmed lawn around your house. Horses like short grass, so lawns that are short - ie closest to the house, are kept nicely trimmed. Within the last 70 or so years this changed as horses were phased out, and more and more people had to use mechanical devices to get rid of the excess grass outside their houses. Most of these use fossil fuels. This series of articles shows you how you can use waste fruit, possibly from your garden, to make your own fuel and cut your lawn sustainably (or make ethanol to power a generator or fuel cell system to make electricity for your house!).

Why make your own lawnmower fuel? This might sound like a silly project, but consider, if there are half a billion lawns in the world with an average size of 100m2, which are mowed 12 times a year, these lawns represent a fuel consumption of about 1.4 million tons. Assuming there are half a billion gardens on Earth with three fruit trees that produce 100kg each of fruit that lies and rots below the tree, if this fruit was fermented to ethanol and used to power lawnmowers, we would reduce the number of fossil fuel tons used by half.

What will you need to make your own petrol (gasoline) lawnmower run on homemade ethanol fuel?

Well first we need to understand fermentation, specifically alcoholic fermentation. Yeast are simple single celled micro organisms that can convert sugar, by reacting it with oxygen, to carbon dioxide and water pretty much the same way we do. In the absence of oxygen, yeasts can convert sugars to alcohol and carbon dioxide, and continue living until the make so much alcohol they die (about 12 to 13%). Humans can also survive for short periods in low oxygen environments, but we have the disadvantage of producing lactic acid instead of ethanol as a by product. The lactic acid damages cellular function, so, too long without air and you die.

C6H12O6 -> 2CH3CH2OH + 2CO2

The above formula shows how a molecule of sugar on the left is converted to two molecules each of ethanol and carbon dioxide. This is a very simple reaction and you would predict that if you had 10 kilograms of fruit sugar to ferment, that you should be able to get about 5.1 kg of ethanol fuel by fermenting the sugar. Just now we will spoil that dream.

From the equation we can also see that oxygen needs to be kept out so that the yeast does not go back and consume that alcohol. So, we need a container. A plastic barrel is quite effective as shown in the picture. The lid keeps the yeast out of contact with the atmosphere. This container is a fermentor - a vessel in which fermentation happens - in other words you now posses a 'bioreactor' that biotechnological device which allows a biological system to produce a product such as ethanol in a controlled contained environment.

Fruit can be simply mashed with a pole and added to the drum. Don't worry about straining it now - the fruit will decompose as it ferments and release more juice than if you separate the fruit fibre from the juice. You are making alcohol for your engine not for your own consumption, so a little bit of wood alcohol getting into the product will not hurt anybody!

Next you need to add some yeast to the fruit juice mix. Fruits such as pineapples have so much wild yeast on them that you don't need to bother with this step. For other fruits such as apples and plums, a little added yeast will help you get alcohol rather than other by products. If possible get an ethanol tolerant yeast, normally these are available from wine or beer maker supply stores.

A hydrometer will give you an indication of how much sugar you have in your juice when you start. As the fermentation goes along, it will show you that there is less and less sugar left - when it tells you there is none, proceed to the next article which shows you how to make a solar still to separate the fuel alcohol from all the other gunk in the fermentor (link to solar still article).

Earlier we discussed the fact that in a perfect world 1kg of sugar would give us 0.51 kg of fuel alcohol, based on the reaction that produces alcohol. This is called a theoretical yield. In reality, your yield of alcohol will be lower as the yeast, like all living organisms, will behave both logically and erratically. Some of the sugar will be used to make more yeast - reproductive activity - which is, as we all know, energy intensive. Some will be used to make mistakes - in beer one often gets a butter scotch flavour when the yeast made a mistake. All in all, this adds up to the fact that you will get a yield of somewhere between 0.3 and 0.4 grams of ethanol per gram of sugar.

Do not leave your fermented raw fuel undistilled - other microbes will get in there and rapidly convert it to all manner of other compounds, most of which will hurt your engine. You need to extract the alcohol as fast as possible.

In pictures:


A drum such as this one can hold 220 litres of fruit mash - don't fill it all the way as it will overflow and make a mess when the fermentation begins. Rather start with about 200 litres. 200 litres of fruit juice with 100 grams a litre of sugar will give you about 8kg of fuel - enough to fill your lawnmower tank 9 times.


Once fermentation begins, the fruit rapidly takes on an unsightly appearance!

[Koula]

http://scienceinafrica.com/old/index.ph ... rstill.htm" onclick="window.open(this.href);return false;" rel="nofollow

Separating your alcohol from your fermented fruit

By Dr Garth Cambray

In the previous article we looked at how to convert old fruit into a fermented mixture containing a small quantity of alcohol. Here we look at a simple, inexpensive way of turning that into a starting material for lawnmower fuel.

A week and a half of fermentation will give you a solution with somewhere between 5 and 10% ethanol fuel by volume. This will not burn in your lawnmower. It needs to be concentrated.

How does one concentrate ethanol fuel from a raw fermented fuel mixture? To do this you will have to separate the ethanol from the other stuff in the fermentation. This is easily done with a still. A still is a device which uses the fact that ethanol evaporates at a lower temperature (78 degrees Celsius) than water (100 degrees Celsius) to separate the two.

Your raw ethanol fuel mixture is heated and the ethanol evaporates before the water and is then taken to another place where the ethanol vapour cools, condenses and runs into a tank. There are many ways of distilling alcohol, some use heat from flames, some use electricity, but we are trying to get away from that, so we are going to show you how to make a solar still � using that great free fireball in the sky, the Sun, to make your own free fuel for you.

To make a solar still, you need a container, a sheet of fibre glass roofing, a little bit of melamine board, some chipboard screws, a tube of silicone, an old towel that is beyond use anywhere else (preferably black � if not dye it black) and some plumbing fittings. Note that to make this I only bought a tube of silicone � everything else was rubbish that was lurking around � this is low cost, and effective and most people will be able to make one from stuff lurking around in the corners of the house and garden.


The things needed to make your still.

Make a trough in the bottom of the container as shown. Seal all parts of the wood with silicone � be excessive here, silicone is cheap, taking this thing apart to fix it later will cost more in time. Put a plumbing fitting into the side of the trough and one into the bottom of the container.


The melamine board trough sealed with silicone.



The bottom plumbing fitting � this is where your condensed alcohol will run out � I cut a groove in the plumbing fitting to let all alcohol out.

Secure the dark towel to the back of the container so that it hangs into the trough.

Secure the fibre glass roofing to the top of the container so that it is completely gas tight.

Allow to dry.

Pour your fermented fuel mixture into the trough � capillary action will draw the water, fruit and fuel ethanol mixture up onto the towel � which � when heated by the sun, will cause the ethanol to evaporate faster than water.


The fermented fruit is poured into the trough through the hosepipe funnel setup. Once the distillation run is over, the pipe is lowered to the ground and it becomes the drain.



The ethanol vapour will rise and condense on the fibre glass roofing and run down to the bottom where it will run out through the bottom plumbing fitting into an outside storage vessel.


The still in operation � note the condensed alcohol on the fibre glass.



Initially the distillate will have a high ethanol content � with time this will decrease. Separate the different cuts into different containers. Some of the later low ethanol cuts can be kept and redistilled later.


The complete set up on the back veranda. Note collection bottle below.

You now have a slightly concentrated alcohol solution. Process all of your fermented fruit juice this way and store it in a tin � take the low alcohol bits and pieces that come out of the still at the end and redistill them a few times.

You will have now managed to convert your low alcohol fermented fruit juice into a higher alcohol � probably 30-40% by volume, distillate. You can put this in the still again and this will allow you to concentrate the alcohol further to 50-70%, depending on how careful you are. This will not however be sufficiently concentrated to run a lawnmower engine. The next step is to build a reflux column, to see how to do this, go to the next article: Making your own reflux column from a piece of old irrigation pipe or some tin cans

[Koula]

And the last article in the series... I love the thought of smelling pineapple plums of smoke from my chainsaw. Much thanks to the author of these articles, as I was previously obsessed with western technicalities and the belief in the need for expensive equipment.

http://scienceinafrica.com/old/index.ph ... reflux.htm" onclick="window.open(this.href);return false;" rel="nofollow

Making your own reflux column from a piece of old irrigation pipe or some tin cans

By Dr Garth Cambray

In the first article in this series we saw how to ferment fruit using yeast, converting the fruit sugars to low grade fuel ethanol. In the second article we saw how to make a solar still to concentrate the fuel ethanol. This article shows you how to concentrate the fuel and use it to run a 4 stroke and 2 stroke petrol (gasoline) engine.

To produce fuel grade ethanol, it is necessary to concentrate as much alcohol as is theoretically possible from the ethanol/water mixture that you get from the solar still. To do this, one needs a reflux column. What a reflux column does is allows you to perform a huge number of redistillations all in one go, thus using as little energy as possible and giving you the highest possible quality fuel. After refluxing, your ethanol fuel mixture will be about 94% Ethanol. To remove the last little bit of water, some plaster of Paris is added. But more about that later.


The parts needed to make the column. Pipe and fittings and stainless steel pot scourers. Make sure they are stainless steel as normal steel scourers will rust.

To make a very simple, yet highly effective reflux column, you will need a 750mm length of black pvc irrigation pipe and fittings for each end to connect it to your boiler on one end and the condenser on the other. A small layer of silicon rubber can be placed around each join when assembling. This will protect against leaks.

Pack the reflux column with stainless steel pot scrubbers. I used the 3M brand scrubbers from the local grocery store.

Alternatively, you can use 5 tin cans (the type that stack into each other). Attach plumbing fittings to the tin can at the base of the column, that will


The assembled boiler, reflux column and condenser in operation.

connect to the boiler, and to the can that will make up the top of the column connecting to the condenser. The cans in the middle should have small holes drilled in them as shown in the picture. The column is packed with stainless steel pot scourers. I stuck the whole thing together with silicon sealant and packing tape.

In the system I use, my boiler consists of an old 45l stainless steel urn. Essentially any heating system that can boil water will work as a boiler for a reflux column. (It is important to ensure that no alcohol vapour can exit the boiler through leaks � so called fugitive emissions as this is a fire hazard and will affect your ability to think clearly near the still).

Attach the boiler with crude alcohol fuel mixture in it, to the reflux column. Attach the reflux column to the condenser. Attach the condenser cooling system to your cold water source.


An alternative reflux column made from old tin cans.

Once the boiler begins boiling, vapour will pass slowly up the reflux column. This vapour will consist of a mixture of alcohol and water. The alcohol and water will condense at different rates as they contact the surface of the packing material in the reflux column. Because alcohol evaporates more easily than water, more vapour entering the column will transfer its heat to the condensed alcohol re-evaporating it, and a little less water, that will then go slightly further up the column, re-condense and be re-evaporated and so this process continues until very clean pure, near fuel grade alcohol comes out the top of the reflux column and enters the condenser, where the alcohol vapour condenses and runs out into your collection vessel.

As time progresses, and the concentration of ethanol in the boiler decreases, the concentration of ethanol vapour entering the reflux column will decrease too. Hence, again, it is important to separate your first cut of fuel from your second, which can go back to the solar still for further concentration.

Your first cut that came from the reflux column, contains a very high concentration of ethanol and some contaminant alcohols and ketones � all of which make good fuel. There is also a small amount of water. This can be removed with plaster of Paris � a powder formed by the heating of gypsum in the following reaction:

CaSO4�2H2O + heat -> CaSO4��H2O + 1�H2O (steam)


An old Stihl chainsaw running on ethanol fuel. This chainsaw was actually manufactured in Brazil when this country was the worlds largest ethanol powered nation and is perfectly suited to ethanol fuel (gasohol). Note the cloud of pineapple and two stroke oil tainted smoke in the picture.

As you can see from the above equation, heat drove water out of the chemical matrix of the salt. When plaster of Paris is added back to a solution with some water in it, the water immediately reacts with the partially dehydrated CaSO4��H2O to return the compound to its hydrated state of CaSO4�2H2O. After this happens it sediments to the bottom of your mixing vessel, and the clear liquid above is fuel grade ethanol.

I mix this with 5% unleaded petrol making the fuel something which only an engine can consume � just in case anybody gets worried about that.

To run your 4 stroke lawnmower engine on ethanol, fill the tank. Start the engine � it will sound a bit different to when it ran on petrol, and will not accelerate properly as the fuel air mixture provided by the carburettor, which is set for petrol, will be a bit lean, as ethanol has less energy in it than the same volume of petrol. You can modify your carburettor to overcome this problem, but then your engine will have the disadvantage of being only alcohol fuel compliant � which if you get bored with making your own fuel could be a problem. I just fiddle with the choke settings on our engines to get it to a point where the engine runs smoothly and accelerates properly.

A two stroke engine, such as that in a weedeater or chainsaw is far easier to run on ethanol than a 4 stoke engine. In our case, for the chainsaw, we just mixed the ethanol and two stroke oil as we would for petrol and then added 5% more chainsaw oil just for good measure as ethanol is a slightly worse lubricant than petrol, hence a little more lubrication is needed for the same volume of fuel.

Making your own fuel gives one a great feeling of independence, and nothing beats the faint smell of pineapple and two stroke oil coming out of the exhaust of a chainsaw!


You may wonder why we don�t show a picture of our lawnmower � well that's because they look like this. But if you don�t have some of these to mow your lawn, make your lawnmower sustainable at least!