# Alcohol directly from plants? **URL:** \ **Category:** Factual Questions\ **Created:** [May 8, 2007, 2:01pm UTC](https://boards.straightdope.com/t/alcohol-directly-from-plants/403234 "2007-05-08T14:01:28Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [May 8, 2007, 2:01pm UTC](https://boards.straightdope.com/t/alcohol-directly-from-plants/403234/1 "2007-05-08T14:01:28Z")
Why can’t we alter plants to make alcohol directly? The current process for manufacturing alcohol (ethanol) is very inefficient: first, you grow sugar cane. Second, you cut the cane, and extract the sugar (sucrose). The sucrose is then used by year plants, which convert the sucrose into alcohol and carbon dioxide. You then must distill the alcohol, after which it can be used as a fuel. Suppose we could alter the plant’s genes, such that the sugar cane cells would contain a yeast gene-and have the plant produce the alcohol continuously-or better yet-develop a plant which would convert water and sunlight into alcohol, without producing sugar. That would solve the energy problem. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [May 8, 2007, 2:05pm UTC](https://boards.straightdope.com/t/alcohol-directly-from-plants/403234/2 "2007-05-08T14:05:33Z")
Yeast only makes alcohol when it is respiring anaerobically. That’s not to say what you’re describing can’t be done, it just makes it perhaps a bit more difficult still. Alcohol is to yeast as lactic acid is to humans - a toxic waste product produced when conditions are less than ideal. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [May 8, 2007, 2:26pm UTC](https://boards.straightdope.com/t/alcohol-directly-from-plants/403234/3 "2007-05-08T14:26:48Z")
> [@](#): > > The sucrose is then used by year plants, which convert the sucrose into alcohol and carbon dioxide. To accomplish this, you’d most likely need to shut down the [Krebs cycle](http://en.wikipedia.org/wiki/Citric_acid_cycle), and rely on [Glycolysis](http://en.wikipedia.org/wiki/Glycolysis) to produce energy for the plant. Unless you also increased the rate of carbon fixation, that’d leave the plant starved for ATP. Assuming you could balance things to the point where the plant would survive, you’d still have an end product, ethanol, with a high vapor pressure, sitting inside leaves, which evolved to have a high rate of gas exchange. Your ethanol would evaporate off, and you’d be left with nothing but a sickly plant. ---
**Author:** ![sweeteviljesus](https://avatars.discourse-cdn.com/v4/letter/s/898d66/32.png) [@sweeteviljesus](https://boards.straightdope.com/u/sweeteviljesus)\ **Post date:** [May 8, 2007, 10:30pm UTC](https://boards.straightdope.com/t/alcohol-directly-from-plants/403234/4 "2007-05-08T22:30:45Z")
One current avenue of research is to develop cheap cellulase to break down plant cellulose into simple sugars and then ferment that into ethanol. Some researchers are trying to turn this into a one step process, i.e. cellulose + enzyme = ethanol. Craig Vintner of human genome mapping fame is, I believe, working on this. Still others are trying to figure out make enzymes to produce gasoline directly from cellulose. So far it either doesn’t work or is too expensive. What I don’t know is either the price difference or the technological blockers. If anyone knows, please post. FWIW, Rob