Yes, there are many varieties of rice wine so fermenting rice to make ethanol is widely done. Not for fuel though.
Rice and corn is best used as food sources, actually. The only reason corn based ethanol is a thing (say in the US) is subsidies and regulation – both in the farming as well as in the ethanol production itself. On its own, corn would very likely would never be a financially viable source of ethanol (maybe things have changed today)
Crops like sugar cane are probably more viable for ethanol production as is done in Brazil but it still requires a fairly hefty subsidy from the government.
Could it be? Yes. Would it be a good idea? No.
The only part of a plant we can easily make ethanol out of is sugars. To a limited extent we can break down the starches to sugars (starch is just a buncha sugars stuck together chemically) but this takes more energy. The protein is essentially entirely a waste. So the seed coat of the rice is worthless and we have to toss it aside. Then we have to heat and convert all they starchy rice into sugar and/or use a lot of things called enzymes like amylase that can do the same process without a lot of heat but are themselves a little tricky to produce in large quantities and only then can we artificially ferment to get ethanol.
Corn and sugar on the other hand already have a large amount of sugar in them. We can essentially just mash these up and just a little bit of enzymes to free up all the sugar to directly convert into ethanol.
Yes.
It would not be a good idea to use rice as fuel. It’s not a good idea for corn either.
For corn, it increases the price of food . Also, once you include the fuel use to grow the plants, no fuel is saved. It’s not green at all. It wouldn’t be profitable without subsidies. It would be the same for rice.
It works for sugarcane in tropical countries because they are easier to transform into ethanol and they are more productive plants. Using grains like corn, rice, wheat, etc is a bad idea.
For producing alcohol drinks, it’s not an issue. All the other component of the rice are part of the drink and contribute to its taste. It’s standard to drink alcohol from plants rather than drink alcohol made by petroleum chemistry.
If you mean as a fuel source, it’s arguable that corn isn’t worth it either. The corn-to-ethanol pipeline is basically created to prop up the price for farmers. When the full production lifecycle is taken into account, it’s actually worse than gasoline for the climate. [https://www.pnas.org/doi/10.1073/pnas.2101084119](https://www.pnas.org/doi/10.1073/pnas.2101084119)
Rice would be even worse because of the methane produced in rice production. Rice patties account for 16% of the methane that humans are responsible for.
Edit: Since this blew up, I’ll add a chemist’s perspective. Any system that tries to produce a crop or turn biomass into a fuel is going to be less efficient than the alternative. There is only a fixed amount of chemical energy that a plant can make from the sun. Converting that into a burnable fuel will cost some of that energy. An internal combustion engine is then only 30% efficient. If you have a source of biomass, no matter what it is, the way to get the most vehicle-miles out of it is to burn it (preferable close to the source) in a plant that generates electricity, then use that electricity to charge an EV.
Production of a fuel is a multistep chemical process. For each step to move forward, either the compounds give up energy, or you have to add energy. Better to go from raw material to CO2, water, and ash in one step.
Yes,
Every starch can be converted to sugar and fermented to alcohol.
For rice they use Koji mold and ferment it to Sake.
Potatoes use a small amount of barley to start to breakdown of starch and after fermentation and distilling you have vodka.
Barley (or other grains) alone can produce alcohol to beer or after distillation whiskey,…
Even in some African countries they use plantains (starchy bananas simplified) and chew on them and spit it out to make a beer. Your saliva breaks the starch down to sugar making it possible to ferment
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