Biogas...corn?!?

[sanctus]

I was not sure if posting this here or in the social science forum, but I propose to discuss only the science part here and move to the other forum when it gets too politic.

 

The question I have is quite simple, why is mainly corn used to make biogas? Why not a non-commestible plant?

 

EDIT:non-commestible=uneatable, just in cas it sounded only english to me but actually isn't

[maikeru]

I don't think corn is being used to make much biogas or biodiesel. Rather, increasing amounts are used to create ethanol, or "bio-ethanol" as it is sometimes called.

 

Edit: You know I wrote a giant post and I just realized I didn't answer your very simple question. I think corn is being considered a prime candidate for biofuel generation because of its widespread cultivation and importance as a food crop in so many nations across the world, and especially because the US produces such a large amount of corn, nearly 50% of the world's total crop. Other sources such as sugar cane are limited by growing conditions and climate (most of the US and Europe don't seem ideal to grow sugar cane) or might not be as profitable or easy for farmers to grow or they may not be aware of the potential of such energy crops, such as prairie grasses. There might be bias toward using cheap, efficient sources from energy companies and bio-ag consortiums such as Monsanto. I think bio-ag companies like Monsanto control destructive monopolies on GM crops, pesticides, and fertilizers, which throttle farmers and consumers alike, but having not done enough research or having enough personal experience with this issue, I'll offer it as personal opinion. Take it for what it's worth. :shrug:

 

I don't think corn is the best crop for biofuel generation, for the following reasons:

 

- A shallow root system makes it dependent on soil moisture and irrigation, although it is more drought-resistant than, say, soybeans (C4 vs. C3 photosynthesis). Fresh, clean water is becoming increasingly precious around the world, and to use it liberally on crops may become harder as climate and weather patterns change or sources become fouled by pollution or manmade problems. Also, many nonrenewable sources of water such as aquifers and groundwater are used to irrigate vast regions that would be otherwise hard to farm or unsuitable for conventional agriculture. Examples are the Ogallala aquifer in the US Midwest and the Wasia aquifer in parts of Saudi Arabia, both of which supply 90% or more of agricultural and municipal water in those areas, with most of the water going toward agriculture.

 

Ogallala Aquifer

Geography of Saudi Arabia - Wikipedia, the free encyclopedia

 

I have heard, although I cannot exactly confirm, that current water use is expected to deplete both of these aquifers in 20 to 40 years. Increases in agriculture and acreage, population, or pollution will shorten this time frame.

 

- The predominant use of monoculture and single, often genetically engineered cultivars, increases the chance that pests, disease, or catastrophic events can wipe out the crop. 50% or more of US corn is genetically modified (GM). These problems also increase the use of pesticides, which creates more problems for the environment, farmers, and consumers.

 

- Current cultivation methods such as regular tilling of fields destroy the quality of the soil and reduce productivity. Productivity can be boosted by adding more chemical fertilizers, but this also creates salinity in the soil, as does too much irrigation (especially in dry areas, where rain or other water sources like rivers & flooding won't carry away salt build ups in the soil as quickly). Putting more acreage under the plow could eventually destroy more land in years to come.

 

- Corn is cold-sensitive and depends on warm to hot temperatures (above 50 F or 10 Celsius) to grow. Erratic changes in weather, temperatures, and seasons put the crops at risk. Global warming continues and weather and temperatures are changing. We need more hardy crops.

 

Maize - Wikipedia, the free encyclopedia

 

- Current efforts to make bio-ethanol from corn seem focused on the starch stored in the seeds, and the rest of the plant is considered waste. A lot of energy is tied up in that "waste." Other methods of making bio-ethanol are looking at converting plant waste or cellulose into ethanol, such as that from sugarcane or switchgrass (one of the prairie grasses of the US Midwest).

 

Ethanol fuel in Brazil - Wikipedia, the free encyclopedia

Switchgrass - Wikipedia, the free encyclopedia

 

BTW, I want to mention that some scientific studies suggest that mixed native prairie grasses produce higher yields of total biomass than monocultures, and they are adapted to the climate and drought conditions. That's an edge that corn doesn't really have.

 

News Releases: UMNnews: U of M.

 

Different species compete with each other, support each other, and fill in so many niches and provide opportunities to other organisms (such as various soil bacteria) that the total system captures more energy efficiently. Much of this ends up as more biomass, which can then be converted into more biofuel.

 

- Corn and its derivative products are used to manufacture everything from animal feed to plastics and high-fructose corn syrup, and increases in the price of corn will raise the prices of food, plastics, biofuel, etc. "America's Heartland," a farming show which I sometimes watch on TV on the weekends, mentioned that about 50% of America's corn crop is turned into feed for chickens and some of the leftover is turned into feed for cattle and hogs. A tremendous amount of resources and land go to grow so much corn to feed animals...and then we also will need to increase acreage of corn to provide more for (cheap?) biofuels. This can only increase stress on other systems and resources as well as increase competition for a limited resource (corn).

 

Maize - Wikipedia, the free encyclopedia

 

- Because corn is dependent on inorganic/chemical fertilizers (NPK), crop and energy prices will also be affected the prices and availability of the raw materials used to create inorganic fertilizers, such as natural gas, mined phosphate, etc. Nitrogen fertilizers are created using the Haber-Bosch process, which produces ammonia, but the raw material is natural gas. About 5% of the world's natural gas is used to create ammonia. More fertilizer use = higher natural gas prices = not-so-cheap corn and biofuels made from it. That sort of defeats the purpose of using renewable energy when nonrenewable energy is consumed to make it.

 

Fertilizer - Wikipedia, the free encyclopedia

 

- As I mentioned, current efforts seem to focus on making ethanol from the corn starch which is turned into sugar and then fermented. Anaerobic fermentation from sugar to alcohol is an inefficient method of refining and processing energy. Much of the chemical energy is lost as heat or to the growth and use by the microbes (yeast, bacteria, etc.) doing the fermentation. Unless you collect and process the microbes and their CO2 and heat for biofuel too, then I see a lot of wasted energy there.

 

Fermentation (biochemistry) - Wikipedia, the free encyclopedia

Ethanol fermentation - Wikipedia, the free encyclopedia

 

If you do this on a massive scale, as will be required for biofuel generation, you will have massive waste.

 

This is all right if you have a large amount of plentiful, cheap, and potentially renewable energy (like hydrothermal energy), where massive waste might be tolerated and the resultant biofuel energy would still be cheap and plentiful. But it's still horribly wasteful and inefficient, IMO.

 

We should know and do better.