If this was 1980 Jerusalem artichoke would be a candidate.

There are a few crops that will meet these requirements, namely sweet sorghum other C4 grasses. I wonder if there is any work on turning sweet potatoes into biofuel. I've seen some studies done in the 90's that have it beating sugar cane in ethanol production hands down.

The problem with biofuels, as I see it, is the same as the problem of solar energy generally. Theoretically we could meet all our electric power needs with solar cells, but practically you have to deploy an awful lot of solar cells all over the place, and this is not easy.

Any green plant, if grown for biofuels, may be looked upon as a solar-energized, naturally occurring, self-reproducing bioreactor. There are trees everywhere in my community, but the problem is: How do you trim branches from all those trees, and then transport said material to processing plants? As with solar cells, you have the problem of solar energy being very diffuse and therefore hard to collect on a large scale.

Nonetheless, although I have never opposed nuclear power and never will, I wish all who are working in the fields of solar cells and biofuels all the best in coming up with solutions to the problems I've touched upon. We need less expensive solar cells so we can afford to deploy them on rooftops, and we need systems to collect weeds and tree branches from here, there and everywhere and transport them to cellulosic ethanol plants.

Alex:
"The problem with biofuels, as I see it, is the same as the problem of solar energy generally. Theoretically we could meet all our electric power needs with solar cells, but practically you have to deploy an awful lot of solar cells all over the place, and this is not easy."
You'd only need 10,000 square miles of land to get all your electricity from solar. Not that much out of the total avalible. This could be done with a square area of land 100 miles per side in the Nevada desert or just from the area inside your cities because roofs ready cover more area than this.
The amount of land needed should be seen in comparison; All of California's electricity can be produced from 200 square miles of sunshine; 128,000 acres of desert land but Lake Mead, behind Hoover Dam, covers more than 200 square miles. The dam itself only products 1/10 the power. Solar plants seem to use a lot of land, but in reality, they use less land than hydroelectric dams for generating an equivalent electricity output, if the size of the lake behind the dam is considered. The same is true for coal plants. A solar plant will not use any more land than a coal power plant - if the amount of land required for mining and excavation of the coal is taken into consideration. http://www.americanenergyindependence.com/solarenergy.html

"Any green plant, if grown for biofuels, may be looked upon as a solar-energized, naturally occurring, self-reproducing bioreactor."
But the difference is in efficiency; a green plant converts only 3% of the light it gets into stored energy, and then we have to use even more energy to turn this into a form we can use. Solar cells OTOH, the most efficient silicon solar cells capture about 25 percent of the sun's energy. Multijunction solar cells combine several materials to capture multiple bands of photonic energy. Today's most efficient combination -- germanium, gallium arsenide and gallium indium phosphide -- boosts efficiency to 36 percent and that's just the begining. Researchers from Lawrence Berkeley National Laboratory, the University of California, and the Massachusetts Institute of Technology have engineered a single material that contains three bandgaps. The material is capable of capturing more than 50 percent of the sun's energy.

"There are trees everywhere in my community, but the problem is: How do you trim branches from all those trees, and then transport said material to processing plants? As with solar cells, you have the problem of solar energy being very diffuse and therefore hard to collect on a large scale."
But with solar cells once you've wired them up the energy collects itself.

"There are trees everywhere in my community, but the problem is: How do you trim branches from all those trees, and then transport said material to processing plants?"

After thinking about this question a little more it occurs to me we already have an answer. Isn't this stuff already being collected?

Don't you collect biomass when you cut your lawn? And you put it into a compost, right? Do you ever use it? Any good city has tree lined streets but you don't see the streets clogged with leaf litter, they have lots of grassy parks/sport fields/etc. but the grass is always trim and neat. Somebody is collecting this stuff the same as the city collects garbage.

Someone calculated that Canada could fuel 3 million cars a year just from the stuff that goes into our landfills. (of course we're a country of 33 million so its only part of the solution)

Yes ai_vin I do collect and bag up my trimmed tree branches and weeds, and so do my neighbors. I'm sure my lawn mowing service knows what they're doing with regard to grass clippings.

What we need to do to harness all this biomass, is to have cellulose-to-ethanol plants in every community to reduce the logistics problem inherent in getting widely dispersed biomass to processing facilities.

Not only will we have to invest the money to build all these ethanol plants, but here's another problem: We are likely to have one BIG alcohol abuse problem, since policing all these facilities is going to be problematical at best.

But then, we have to do something to meet our energy and mobility needs.

there's a waste product generated in every state, including la, and that's grass clippings. this stuff is already finely chopped and wet...i'd about bet it has a place in the biofuel feedstock line-up...

Any and all biofuels, except from materials now going to landfills, are false economy and fraudulent propositions of local and federal politicians and others who do not spend the time to get to the actual facts of energy use and production and costs. The price of crude oil is being kept artifically high by Congress and the President who refuse to recognize that crude oil is not a free market and that there can be no allowing of speculation of any type on crude oil natural gas or related financial derivatives. Renewable energy proponents have no idea of the enormous actual costs of solar power, wind power, or biofuels compared to the present costs of mining coal or drilling for and pumping oil or gas. There is almost no city in the US where it would be financially practical to install any number of solar cells, and it would be far cheaper and more efficient to install home and business cogeneration units rather than ordinary gas fired furnaces.

Less than ten years ago, China ordered and had built and delivered two CANDU power plants from Canada on time and under budget, and they have been in operation for a few years now producing electricity at far less than the cost of imported coal even. It will only take a few years to pay off the capital and interest costs.. Your car never pays off its capital and interest costs. ...HG....

Louisiana's senator in D.C. seems to be for drilling anywhere and everywhere for oil. When an oil and gas state starts talking renewable, I begin to wonder about their real objectives.

----"Renewable energy proponents have no idea of the enormous actual costs of solar power, wind power, or biofuels compared to the present costs of mining coal or drilling for and pumping oil or gas."------

Take away the estimated $350-400 in subsidies, tax breaks, give aways, special favors and outright girts to the fossil fuel industries at taxpayer expense.

Then let's see which is more expensive. Mining coal for instance---it takes a LOT of work and expense to mine coal, just to burn it once and leave the land destroyed, watersheds polluted, and the air polluted. Just for something that you can only burn once. What is the cost of that?

Coal is not cheap. The price is just very cleverly hidden.