DISADVANTAGES OF BIOMASS - PART IINO FREE RIDE FROM BIOFUEL
_________________________________________________________________ Continued from Disadvantages of Biomass - Part I _________________________________________________________________ Daily Biofuels News Digest Free subscription to biofuels "must-read" daily newsletter. _________________________________________________________________ The United States of America now consumes 7.5 billion barrels of oil annually. That’s 315 billion gallons. How and where do we get enough biofuel to meet demand? _________________________________________________________________ _________________________________________________________________
President George W. Bush made dozens of speeches in which he mentioned the hope for switchgrass as a feedstock for biofuel. Those speeches were far more than political blowing, not that our politicians aren’t entirely capable of just that.
Switchgrass is an excellent biofuel feedstock. It’s a tall (can grow to 12’ high), tough, drought resistant, insect resistant, fast growing prairie grass. Switchgrass harvesting is like mowing a yard and leaves living grass behind to continue absorbing CO2, grow more feedstock, and prevent soil erosion. It provides good grazing for livestock. And, to top it all off, it promises a good yield of biofuel per acre.
The Department of Energy Biomass Report cited earlier shows that switchgrass yields about 2 barrels of ethanol for every ton of switchgrass.
This Department of Energy Switchgrass Genetics Report states that we can expect switchgrass production levels in a range of 7 to 10 tons per acre, depending on rainfall and other factors. And the D.O.E. is working to increase those numbers. Putting the switchgrass numbers together we get 2 barrels of ethanol per ton, and an average of about 8.5 tons per acre, which gives us an expected average ethanol yield of about 17 barrels of ethanol per acre. So, the advantages of switchgrass are big. Switchgrass ends energy conversion disadvantages of biomass. It ends any CO2 disadvantages of biomass. Because its a pure energy crop, it virtually eliminates the price disadvantages of biomass. And because it grows efficiently, it greatly reduces the 'food or fuel' disadvantages of biomass from other crop sources.
Where do we grow it?
Some cornfields may be replaced with switchgrass, but not many. Remember, we need the corn to feed our livestock. There are 39 million acres of idle land, most of which are in land bank programs. But we need to think of those acres as food reserves. The other almost 900 million acres of farmland is already in use producing food.
A small part of that cultivated land is available for switchgrass production. A United States Geological Survey Irrigation Report shows that the United States has over 60 million acres of irrigated land. 28 million acres of that land is under spray irrigation (similar to lawn sprinklers).
The main type of spray irrigation is referred to as a Center-Pivot Irrigation System . Center-pivot irrigation, as the name implies, is nothing more than a suspended pipeline with holes in it that rotates around a center point. This type of irrigation produces circular crop patterns (no, not crop circles) in square fields.
For the sake of discussion, let’s assume that about 20 million acres of the 28 million acres using spray irrigation use center-pivot sprayers. Every field that uses center-pivot irrigation looses about 21.5% of potential crop production because fields are square and the irrigators are circular. Those dry areas are good places for a tough grass crop like switchgrass.
If 4.3 million acres of that 20 million under center-pivot irrigation is used for switchgrass production, we can expect a yield (using low numbers for dry areas) of about 14 barrels per acre. That would give us annual ethanol capabilities of about 60 million barrels a year on land that is otherwise unproductive.
We have other usable but currently unproductive land available. According to Department of Transportation Interstate Highway Data , we have 46,726 miles of interstate highways with a required minimum median width of 36 feet. Those highways have about another 10 feet of grass on either side of the road.
To use easy numbers, let’s say we have an average total grass width of 52 feet. 52 is one fourth of 208, which is just about the length of one side of a square acre. Let’s say that 40,000 miles of our interstates are outside of city areas (which often have no median). With a grass width of 52 feet, and 5,280 feet to the mile, we find that we have about 6.35 acres of tillable land for each mile of interstate. So 40,000 miles of interstate gives us about 254,000 acres that should easily be able to produce an average of 14 barrels per acre for a total of about 3.5 million barrels of switchgrass-based ethanol a year.
3.5 million barrels of ethanol from our Interstate Highways isn’t a very big percentage of the 7.5 billion barrels we need annually. But it does put otherwise unproductive land to good use. The mowing has to be done anyway and switchgrass production from this land resource is good management policy that does not add land use problems to the disadvantages of biomass. And there is a certain poetic beauty to the notion of using highway lands to provide fuel for the vehicles that run on them.
So far, we have seen annual biofuel production possibilities of a theoretical 960 million barrels from corn, 60 million barrels from switchgrass in unproductive areas of irrigated fields, and 3.5 million barrels from highway grown switchgrass. We’re not even one-fourth of the way to meeting our demand for foreign oil.
We do have 580 million acres of grassland pasture. It’s already in use as grazing grounds but its productivity could be greatly increased with irrigation since much of that land is in relatively dry areas not really suitable for crops.
It is not unreasonable to suppose that a good irrigation system could double the productivity of that land. That would enable our livestock to graze on half (and probably less) of the current acreage, thereby leaving 270 million acres or so of irrigated land for switchgrass crops.
If that 270 million irrigated acres produced an average switchgrass crop of 17 barrels per acre, we would harvest 4.6 billion barrels of ethanol a year. That would add enough extra capacity to wipe out our foreign oil imports and cut our domestic fossil fuel oil use by over forty percent.
We also have 641.5 million acres of forest land that contains millions of acres of forested grazing land. The same irrigation system can be used to improve the productivity of our forest areas in relatively dry areas.
Last but not least, we have the Special Use Areas – 285 million acres, and the ‘Other Land’ – of 301 million acres. That’s a total of 586 million acres. Yes, a lot of it involves National Parks and Forests. Remember, we are just looking at our resources here; we will ultimately decide what to do with those resources on an acre-by-acre basis.
Several million acres is also in use on military bases. And Desert USA highlights the 342,400,000 acres of desert that is virtually unused.
Since irrigation is the key to improving growing conditions on most of that available land we have to decide how much of it we are willing to irrigate, and how. The project would be huge, involving irrigation of land areas on the order of five times greater than the 60 million acres now being irrigated. But we do have the technology to do it.
One of the central disadvantages of biomass that relates to many of its other problems is that biomass has to have water to grow. And it needs land to be produced.
Our available land resources aren’t all arid. Some are on the opposite end of the water spectrum. Those ‘Special Use’ and ‘Other Land’ areas mentioned above also contain vast wetlands (including swamps and marshes).
This EPA Wetlands document shows that 175 million acres of Alaska is wetlands. In fact, most of Alaska’s 365 million acres are unused as shown in the Farm Resources Report (Table 9 – 10). And an EPA Vital Wetlands Document (Page 11) reveals another 103 million acres of wetlands in the lower 48 States.
That’s a total of 278 million acres of wetlands. What portion of it should we utilize for food or biofuel feedstock production; should we use some of it, all of it, or none? If we can find viable ways to irrigate our more arid regions we may not need to use any of it. Should we do that? Do 342 million acres of arid land and 278 million acres of wetlands provide enough surplus land to overcome land use disadvantages of biomass? Is that total of 620 million acres of available production land enough to end concerns about 'food or fuel choice' disadvantages of biomass? These are the kinds of questions we need to answer if biofuels are to become a reality.
But I’m getting a bit ahead of myself. Lets look at some other biomass options.
So far we have focused the 'food or fuel' disadvantages of biomass issue on methanol production from corn or switchgrass. Biodiesel has also been in the headlines lately so let’s take a look at that option. We’ve heard a lot about it and soybeans as a feedstock. We won’t spend much time on this because it won’t work.
Here are the production numbers. Referring again to the Farm Resources Report (Table 9 – 23) we see that soybeans produce an average of about 38 bushels per acre.
The Department of Energy Biomass Report shows biodiesel yields from soybeans of about 1.5 gallons per bushel. Crunching those numbers gives an annual yield of just 1.36 barrels of biodiesel per acre.
To produce enough diesel to replace just one-fourth of our imported oil, or about 1 billion barrels a year, would require soybean crops on 735 million acres of farmland; or one-third of the entire landmass of the United States.
We just don’t have enough land to utilize soybeans as a realistic biofuel feedstock. And because soybeans are a food crop, their use as a biofuel would mean trading food for fuel. Judging from the numbers, increasing biofuel production from soybeans would turn the disadvantages of biomass into the disasters of biomass.
Crunching the numbers on rapeseed and other oilseed crops will also produce dismal results. But don’t count biodiesel out of the picture yet.
This Environmental Protection Agency Biodiesel Report shows that 3 billion gallons of vegetable oil are disposed of annually. With only minimal refining, every drop of that can be used as diesel fuel, and give us 71 million barrels of diesel fuel that would otherwise be thrown away every year. And it can be done with none of the disadvantages of biomass from other sources. It’s not a lot, but why waste it?
An Oak Ridge National Laboratory Biomass Report estimates that we throw away of 510 million tons of trash annually. According to an Energy Efficiency and Renewable Energy Biomass Report (EERE is a division of the United States Department of Energy) all that trash has the following composition: 35.2% paper; 12.1% yard trimmings; 11.7% food scraps; 11.3% plastics; 8.0% metals; 7.4% Rubber, Leather, and Textiles; 5.3% glass; 5.8% wood; and 3.4% other stuff.
Virtually everything in that trash mix, except the metals and glass, can be processed into biodiesel. Brian Appel of Changing World Technologies has developed a process that can convert 86.7% of that solid waste into diesel oil and other usable elements at a rate of about two-thirds of a barrel for every ton of solid waste. The conversion would yield about 340 million barrels of diesel a year, recycle the other chemical elements of our trash, and make landfill trash dumps obsolete.
The technologies developed by Brian Appel can also be used to convert millions of tons of animal waste from U.S. meat production. The list of waste to biodiesel opportunities goes on. Once again, technology has created a situation where many disadvantages of biomass use become advantages. And this is just a small fraction of the hope and promise of biodiesel.
Go to Biodiesel on Wikipedia. Scroll about halfway down the sheet until you get to the Feedstock Efficiency Table. At the bottom of the table are production levels for algae that translate to average annual production possibilities of about 240 barrels of biodiesel per acre – from pond scum.
Using cultivated algae as a biodiesel feedstock is the most land use efficient feedstock known. Algae to biodiesel technology is scarcely discussed in the news media, yet it may be the singularly most important technology developed in the last fifty years.
At production rates of 240 barrels per acre, 32 million acres of algae production can produce enough annual feedstock to replace 100% of our 2006 fossil fuel oil consumption. Thirty-two million acres is about 1.4% of the total landmass of the United States.
The resources used for biofuel production from algae are so tiny that this method can virtually elimate the land use disadvantages of biomass. Biofuel from algae ends the 'food or fuel' disadvantages of biomass. And can turn the price disadvantages of biomass into an outright advantage. If fossil fuel consumption is a disease, algae technology may be the penicillin. This exciting technology has not yet proven to be both workable and economical, but it’s getting there. ________________________________________________________________
The use of biofuels means dedicating a portion of our land resources to the production of biomass feedstocks. Though we are a highly technical and advanced civilization, we are as bound to the land as our ancestors of five thousand years ago. As our population continues to grow, eat, and drive, we will have to decide what level of land use is both acceptable, and sustainable.
________________________________________________________________ DISADVANTAGES OF BIOMASS SUMMARY
For those of you who were in a hurry to get to the bottom of the page, here is a brief summary of its contents. We detailed the five primary disadvantages of biomass as follows:
Energy Conversion Disadvantages of Biomass - Disadvantages of biomass energy conversion referred to the fact that it took more energy to make biofuel than was given up by the biofuel when it burned. That is not the case today, at least in the opinion of most of the scientific community.
CO2 Emission Disadvantages of Biomass - Many are concerned that burning biomass produces excess greenhouse gasses in the form of CO2 (carbon dioxide). While biomass does emit CO2 when burned, it actually can remove more CO2 than it emits. But, if it’s not carefully managed, as is often the case in third world countries, biomass use can contribute to deforestization. And deforestization decreases the ability of living biomass to remove CO2 from the atmosphere. Air Pollution Disadvantages of Biomass - When used as a solid fuel for heating and cooking, several disadvantages of biomass become apparent. Unrestricted burning of wood and dung, typically in third world countries, cause the release of particulate matter and sulfur dioxide. In heavily populated areas, this unrestricted use contributes heavily to air pollution, lung disease, and acid rain.
Price Disadvantages of Biomass - Because biomass for fuel often has multiple uses, it carries high feedstock costs. For example, corn biomass is also used for livestock feed, human food, and liquor production; all of which cause corn to be more expensive than it would be otherwise. Ethanol typically delivers less mpg than gasoline and must be priced cheaper than gasoline to remain competitive. Those and other price disadvantages of biomass can create economies that can bankrupt many biofuel operations; it has happened before and it can happen again. Fuel or Food Disadvantages of Biomass - Both food and biomass fuel feedstock require land to grow on. In some cases, future land use may be a choice between growing food crops or fuel crops. If biomass fuel is to become a reality, we need to decide which crops will be grown on what land. The ultimate question is whether or not we have enough land to grow crops for fuel, and crops for food. _________________________________________________________________
Enough said about the disadvantages of biomass. Biomass fuel production, like everything else in life, has challenges. Rather than the disadvantages of biomass, we should speak in terms of the challenges of biomass. When we start to see the disadvantages as challenges, we start to see the advantages of biomass. _________________________________________________________________ BIOMASS PRODUCTION SUMMARY
Acres of each crop required to replace annual fossil fuel oil usage of 7.5 billion barrels. [One barrel of oil equals 42 U.S. gallons; bbl/a = barrels/acre]
2,260,000,000 acres – Total landmass of the United States 5,000,000,000 acres - Soybeans to biodiesel at 1.5bbl/a 833,000,000 acres - Corn to ethanol at 9bbl/a 682,000,000 acres - Corn+stover to ethanol at 11 bbl/a 441,000,000 acres - Switchgrass to ethanol at 17bbl/a 31,000,000 acres - Algae to biodiesel at 240bbl/a [Note: All of the above resources have fuel byproducts. For example, biodiesel can be processed from distiller’s corn after ethanol production. Those resources also involve an energy cost in their production. To one degree or another, fuel gained from byproducts will offset fuel lost to production. A large number of other variables also effect the overall energy return from a given resource. For those reasons, the figures above reflect only the estimated gross production levels of each resource.] _________________________________________________________________ The Real Goods Homepage _________________________________________________________________
Return To Disadvantages Of Biomass - Part I
|
