Friday is here, and the 'A Taste of Science for the Weekend' corner is back — number 66.
This time: how to turn sugarcane into fuel, and the connection to wine, cosmetics, and taxes.
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Ethanol is a fascinating compound.
It combines an ethyl group (made of carbon and hydrogen atoms) that is electrically nonpolar and therefore repels water, with a hydroxyl group — which contains oxygen. The oxygen is electrically polar and bonds readily with water.
This unique combination allows ethanol to mix with both water and organic (carbon-based) substances.
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We encounter ethanol as the alcohol in alcoholic beverages, as a solvent in the pharmaceutical and cosmetics industries, and as an antiseptic against bacteria.
Ethanol also serves as a gasoline additive, because it reduces instances of spontaneous ignition of fuel in the engine, thereby preventing engine damage caused by irregular fuel-ignition timing.
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Ethanol is considered a relatively environmentally friendly fuel.
It can be produced from plants through a process that is less polluting than gasoline, and because it also contains oxygen, its combustion produces carbon dioxide rather than toxic carbon monoxide.
For this reason, in certain countries it is the primary fuel component for automobiles, even though its energy efficiency is about 30% lower than that of gasoline and it still emits polluting carbon dioxide.
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Ethanol can be produced from plants such as sugarcane, corn, wheat, and the like.
The sugars from these plants are mixed with yeast in oxygen-free containers.
The yeast consumes the sugars as food and releases ethanol and carbon dioxide.
To raise the ethanol concentration for industrial use, it must be distilled by vaporizing the ethanol in order to separate it from the other components.
Another option for producing especially pure ethanol for industry is based on a chemical process in which ethylene — a gas derived from crude oil or natural gas — reacts with an acid catalyst and steam at high pressure and temperature to form ethanol.
This process yields purer ethanol, but the process itself is polluting.
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Ethanol intended for industrial use or as fuel is first mixed with a denaturant such as methanol — an especially toxic alcohol — in order to exempt it from the taxes that apply to potable alcohol.
Ethanol has future potential as a clean fuel source for wider use, since it can also be produced from cellulosic waste such as plant trimmings or from algae.
Shabbat Shalom 😊
#ATasteOfScienceForTheWeekend
In the video: an ethanol production plant using sugarcane. Credit: SweeterAlternative channel on YouTube.