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For all of its advantages, there are a number of disadvantages of biomass that some find unacceptable. Biomass is not quite the perfect energy resource advocates want it to be. Any resource we attempt to harness will involve a number of tradeoffs and biomass is no exception.

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One of the major disadvantages of biomass fuel appears to have been overcome. In its early development stages, liquid biofuel used more energy to grow and manufacture than it delivered in the form of usable fuel. A gallon of ethanol took more than a gallon of fossil fuel to generate when considering the fuel needed to plant, fertilize, irrigate, harvest, transport, ferment, distill, and deliver corn based ethanol to the gas pump.

Several key developments have produced liquid biofuels that deliver more usable energy than is consumed in production. Genetic engineering has produced corn that delivers far more crop per acre than just a few years ago. Continuing refinement of fermenting techniques has enabled producers to use not just the corn, but also the stover (stock, leaves, and cobs), potentially adding nearly 35% to the production of each acre of corn.

Maybe the most significant advancement in biofuel production is the use of Switchgrass as a biomass feedstock for biofuel. On average, switchgrass promises to deliver twice the energy per acre as corn. In addition to those advancements, the conversion process that turns corn and other crops into ethanol has experienced increased efficiencies every year, and that trend continues.

The end result of these advancements is that we can expect alcohol based fuel production returns in the area of 6 Btus (British thermal units) for every Btu of liquid fuel needed to produce the fuel supply. That compares to returns of less than 1 Btu of ethanol for every Btu of fuel using 1980’s technologies. By most accounts, the negative energy disadvantages of biomass alcohol fuels are long gone.

I need to qualify the above statement a bit. This Department of Energy Ethanol Fact Sheet states that ethanol production now generates at least 1.35 Btus of fuel for every Btu required in creating ethanol and getting it to the gas pump.

The largest energy user in this process is the heating and distillation of the mash to boil out the ethanol (yep, it’s the same process used to make moonshine).

If the energy for heating and distillation comes from coal, natural gas, or other non liquid, local energy resource, then the energy returns come out to over 6 Btus of ethanol energy for every Btu of liquid fuel (IE fossil fuel oil) involved in its production. And, as you will see in the next section, if we use geothermal energy to distill ethanol we gain benefits beyond a large reduction in liquid fuels used to produce ethanol.

There are some who hotly dispute current thinking on biomass as a viable fuel resource. At the top of the list is David Pimentel, PhD, Professor of Insect Ecology and Agricultural Sciences at Cornell University. Dr. Pimentel’s Ethanol Research Paper argues that there are a number of major disadvantages of biomass fuel including negative energy returns, economics that don’t work, and destructive environmental consequences.

An Argonne National Laboratory Ethanol Energy Paper disputes Dr. Pimentel’s findings for a number of reasons stated in the report. One interesting argument (page 24) against energy return disadvantages of biomass is that all research (including Dr. Pimentel’s) clearly shows an upward trend in energy return efficiencies for ethanol. Though a number of the charts in the Argonne paper are difficult to interpret, it still makes for interesting and informative reading.


Who is right?

The majority of professionals believe that we are, indeed, getting a positive energy return from biomass. They also believe that the advantages of biomass far outweigh the disadvantages.

The most solid evidence in favor of positive energy returns, however, probably lies in the amount of investment dollars put into biofuel production facilities.

Investors aren’t going to knowingly put money, especially the huge sums needed for biofuels expansion, into any project unless they have a high probability of showing a profit. It follows that negative energy disadvantages of biomass would kill any chance of long term profits. And biofuel production facilities, built with private investment dollars, are popping up like mushrooms.

Then again, the U.S. Government is still heavily subsidizing the ethanol industry with tax breaks and loan guarantees. Those juicy subsidies may well be attracting investment dollars that wouldn’t exist without Government involvement. So, the debate about the viability of biofuel, like the Energizer Bunny, keeps going and going.




Some would suggest that one of the disadvantages of biofuel is that it releases carbon dioxide into the atmosphere when burned. The carbon dioxide concerns go beyond the burning of ethanol and include the fossil fuels consumed to create ethanol and deliver it to the gas pump.

Biomass absorbs and stores carbon dioxide while it is growing. Biofuels are at least carbon neutral in that the carbon dioxide they release when burned has been absorbed from the atmosphere when the plants were growing. Most scientists believe that, when everything is considered, CO2 emission disadvantages of biomass are nonexistant, and biofuels actually reduce greenhouse gasses.

How? When you mow a yard most of the grass is left behind and it continues removing CO2 from the atmosphere. It’s the same thing with switchgrass because a lot of green, CO2 absorbing switchgrass is left growing after harvesting the mowings. Corn also absorbs large amounts of CO2 when it’s growing.

An Argonne National Laboratory Ethanol Study states that corn based ethanol actually reduces atmospheric carbon dioxide by a factor of 18 to 29%. For every 100 lbs of CO2 emitted when corn based ethanol is burned, the corn had already absorbed 118 to 129 lbs of CO2 when it was growing.

The figures for CO2 absorption by cellulosic (switchgrass for example) ethanol are as high as 85%. The Argonne report doesn’t say whether or not it factored in CO2 emissions involved in the distilling process, but it probably doesn’t matter much if...

In the very near future we see low temperature (about 200 degrees F) geothermal resources used in the ethanol heating and distilling process. Geothermal heating and distilling will drastically reduce any CO2 disadvantages of biomass during those phases of ethanol processing. That may make ethanol and other alcohol based biofuels so environmentally friendly that their large scale use could actually reverse the century long trend of increasing atmospheric CO2 levels.



Another one of the disadvantages of biomass that is not exactly related to auto fuel but still important is that a lot of biomass in the form of wood and dung is burned in millions of households around the world. Hundreds of millions of people still use solid biofuel for heating and cooking, and some are here in the United States.

Most solid biomass in the U.S. is burned in power plants as a coal supplement. An EERE Biomass Co-firing Report (Office of Energy Efficiency and Renewable Energy under the Department of Energy) details the cost effectiveness and other concerns of biomass fuel used with coal to fire power plants.

Solid biofuel burned without filters or water spray type scrubbers releases pollutants and particulate matter into the atmosphere. While U.S. power plants carefully control stack gasses to minimize air pollution disadvantages of biomass, other countries aren’t so diligent with their use of biofuel.

Chief among the disadvantages of biomass is that in heavily populated areas or when used indoors, biomass air pollutants can and do cause lung disease. And uncontrolled use of solid biofuels in third world countries is heavy in the extreme.

In addition to creating some of the most polluted cities in the world, this kind of uncontrolled biomass burning contributes to deforestation and decreases woodland capacity for carbon dioxide absorption from the atmosphere.

Last but not least, biofuels also contain sulfur, which contributes to acid rain. So, while biofuels may offer us an alternative to crude oil, they also come with a cost, both environmental and financial.



Huge fossil fuel oil price increases and major biofuel cost improvements made many of the price disadvantages of biomass disappear between about 2002 and 2005. Before then biomass fuels did cost more to produce than fuel from conventional crude oil resources.

2006 is a great time to be in the ethanol business. Though the focus of this United States Department of Agriculture Ethanol Report is on ethanol production from sugar cane and sugar beets, it also has data on ethanol production from other resources including corn. The report shows that post Y2K production costs for corn-based ethanol in a modern facility are less than $1.25 per gallon of ethanol.

In rough numbers, that price breaks down to operating costs of about $.52/gallon, corn costs of about $.53/gallon (based on corn at $2.10/bushel), and capital recovery costs of $.12 to $.14/gallon. That gives a total of $1.16/gallon to $1.18/gallon.

The capital recovery costs are based on costs to build a refinery averaging about $1.40/gallon of capacity, with larger facilities enjoying a cheaper cost per gallon. Those costs are amortized for 20 years at 7%apr.

The cost of corn has the greatest effect on production costs and is a big reason for long term price disadvantages of biomass based ethanol. The corn cost figure of $.53/gallon reflects an ethanol yield of 2.5 gallons/bushel. That $.53 is the net cost of corn for ethanol. The $2.10/bushel price and 2.5gallon/bushel gives a cost of $.84 per gallon of ethanol.

Why is that? One interesting aspect of corn based ethanol production is that it doesn’t actually use up the corn (an important point for the next section). After most of the starches are processed out of the corn, a considerable amount of high protein grain, corn oil, vitamins and minerals are left behind. This residual, referred to as Distiller’s Grain , is sold as livestock feed. That means that a corn cost of $.84/gallon leaves about $.31/gallon of marketable distiller’s grain which eases the actual cost of the corn to the $.53 mentioned in the preceding paragraph.

A significant aspect of marketable distiller’s grain is that corn prices can double without causing net ethanol feedstock prices to double. The relationship between the two prices often varies and corn prices can increase without a corresponding increase in distiller’s grain prices. Though distiller's grain helps, it does not eliminate the price disadvantages of biomass from corn feedstocks.

Market pressures for ethanol now are bidding the price at and above the $3/gallon price of gasoline. That’s due mainly to the fact that ethanol is rapidly replacing toxic MTBE gasoline additive and creating a temporary high demand that may abate as more ethanol comes into production. Then again, a generally higher demand for ethanol will, almost certainly, cause corn prices to increase.

And the ethanol business has other concerns. Some Biomass Energy Problems are difficult to overcome.

One of the big disadvantages of biomass based ethanol is that it has a low energy content compared to gasoline. The lower energy content means that cars fueling with ethanol will get less mileage. So, if gasoline costs $3.00 per gallon, then E85 fuel mix (85% ethanol) priced at $2.15 per gallon is just about equal in value because it reflects the 28% loss in mileage.

That permanent discount for ethanol means that the risk of corn-based ethanol becoming uncompetitive with gasoline is greater than it would appear at first glance. If gasoline prices drop, ethanol will remain competitive only so long it can be priced about 28% lower than gasoline.

Far larger disadvantages of biomass fuel sources in general and ethanol in particular lie in the fact that corn prices can easily increase as oil prices decrease. It has happened before and the odds are high that it will happen again. If it does, without government help, the price disadvantages of biomass could spell financial disaster for biofuels.

Without the tax breaks currently in place for ethanol, it becomes uncompetitive at gasoline prices of about $2.25 per gallon of regular. And that’s if corn stays at cheap 2006 prices, which is unlikely.

One big factor that will keep pricing disadvantages of biomass high is that most biomass feedstocks have other uses besides fuel. A huge amount of the corn, grain, and grasses that could become biofuel are used to feed the beef, pork, chicken, and so on that we eat. Even allowing for distiller's grain byproducts, corn methanol will add upward price pressure to corn prices.

We also eat vegetables and grains (but not grasses, at least not most of us). Corn stover, which is the stock, leaves, and cobs left behind after harvesting corn, can be utilized for fuel production; but it is also put back into precious field soil to prevent erosion. Trees can be used as biofuel; but they are also used to make furniture, houses, paper, and a host of other products. The list of competing uses for biomass feedstocks could fill volumes.

Those other uses cause built in price disadvantages of biomass resources, and can translate into high biofuel prices relative to the cost of crude oil. When fossil fuel prices are relatively high, biofuel prices are attractive. But when fossil fuel prices drop, as they often do, they can drop enough to make biofuels uncompetitive. If that happens we could see a huge number of biofuel operations shut down.

The basic laws of economics dictate that, unless more crop land can be found and utilized, or unless higher yield crops are developed (which is, in fact, happening), biofuel will create more demand on current biomass feedstocks such as corn, grasses, and trees. More demand, of course, usually translates into higher price disadvantages of biomass.

One big key for sustained success of biofuels is the development of Cellulosic Fermentation technologies that will enable the use of crops like switchgrass as a feedstock. Switchgrass would be virtually a pure energy crop with few competing demands on the supply, and few of the price disadvantages of biomass from other sources.

If oil prices fall drastically, switchgrass prices will likely do the same to stay marketable. That is not the case with corn and most other biomass resources. Fortunately, cellulose fermentation technologies are far along the development road and have the potential to be in full, competitive production by 2010.

Biomass fuel technologies are advancing rapidly and producing ever cheaper fuel supplies while fossil fuel supplies appear to be getting more difficult and expensive to produce. The price disadvantages of biomass could soon become a memory. But the biggest question about biofuels is whether or not we can actually use them - - and eat.




[Note: If you want to skip the important, but somewhat tedious, documentation and number crunching in this section, you can jump to the end of Part II for a summary.]

Among the disadvantages of biomass is the concern that, in a world with an ever-growing population that needs to be fed, we wonder if biofuel use forces us to choose between crops for food, or crops for fuel. Or do we need to choose at all?

The crops or food question is one of land use and biomass productivity.

One of the biggest disadvantages of biomass as a fuel focuses on the volume available in relation to the volume needed. That is dictated by how much land is dedicated to growing food crops, how much land will be needed for biofuel crops, and if we have enough land to do both.

The answer, as with many questions about the disadvantages of biomass, is a bit complicated. Let’s look at some facts and figures about U.S. agricultural capabilities. (While the information in this section applies only to U.S. agriculture, some readers may find similar situations in their home countries.)


The United States Government keeps excellent agricultural statistics. A large part of the data you will see below comes from a recent United States Department of Agriculture Farm Resources Report (which we will refer to as the Farm Resources Report). The data retrieved from this document is as follows:

Total Land in Farms - Table 9-9

Land Use - Table 9-10

Alaska Land Use - Table 9-10

Acreage in Livestock Grains - Table 9-22

Acreage in Corn Livestock Feed - Table 9-23

Soybean Production - Table 9-23

The report is a good summary of U.S. agricultural capabilities.


Among other things the report shows that the 50 states comprising The United States of America contain a total of 2.26 billion acres. (An acre of ground measures about 208.7’ by 208.7’ and totals 43,560 square feet. A square mile, by the way, contains 640 acres.)


The land is used as follows (Table 9-10 USDA Farm Resources Report ):

Crops - 349 million acres.

Idle Land – 39 million acres.

Pasture Land – 67.5 million acres.

Grassland Pasture – 580 million acres.

Forest Land – 641.5 million acres (including forested grazing land).

Special Use Areas – 285.5 million acres (rural roads, federal and state recreation and wildlife areas, military bases).

Other Land – 301 million acres (deserts, swamps, marshes, rocky areas, and other urban and special use areas not otherwise inventoried.)


The total amount of land in farms of all types is 936,600,000 acres (Table 9- 9 Farm Resources Report). This is a preliminary number in the report and doesn’t quite equal the total of 996,500,000 acres shown above for Crops, Pasture Land, and Grassland Pasture. For our purposes, as you will see, the numbers are close enough.)

Feeding livestock uses 733 million acres. In addition to the above 67.5 million acres of pasture land and 580 million acres of grassland pasture, another 86 million acres is invested in grain crops for livestock (Table 9- 22 Farm Resources Report).


And we have a lot of livestock to feed. Page 50 of this USDA Livestock Report shows U.S. livestock numbers as follows:

95 milion cattle

60 million hogs

6 million sheep

450 million chickens

When it’s all said and done, the feed that feeds the animals ends up feeding us.


Another 250,000,000 acres (give or take a few) grows food crops such as wheat, more corn, potatoes, sugar beets, soybeans, and many others. The total amount of land dedicated to feeding people is almost one billion acres. That leaves about 1.26 billion acres not used for food, but that doesn’t mean it’s not used.

The rest of the land in the inventory is composed of cities, houses, highways, military bases, National Parks and National Forests, mountains, swamps, deserts, tundra, and a host of other defined uses. By defined uses I mean that we are defining how our land is currently used, and that definition changes daily according to our needs.

So, where does that leave us in the food or fuel question? At first, it sounds like all of our land is already being used. But we are ever inventive in redefining how land from one end of our country to another is used.

Let’s look at the possibilities, some of which many may not like but we are just examining the resource base and ways to use it. What we ultimately do with those resources will be decided by scientists, developers, farmers, engineers, environmentalists, and government. In other words, we will decide it. So please don’t shoot the messenger (that’s me).

Lets look first at corn-based ethanol since it is currently the primary biofuel. This is going to take some number crunching but bear with me. We need the numbers to determine whether or not biofuel dreams are realistic.

Rounding off more data from the Farm Resources Report (Table 9-23) we find that from a total feed grain crop of 86,000,000 acres, we have about 80,000,000 acres of corn crop that produces 12,000,000,000 bushels of corn a year for livestock feed. That averages out to about 150 bushels per acre, which is a 50% increase over just ten years ago thanks mainly to bioengineering.

This Department of Energy Biomass Report shows that corn will yield about 2.5 gallons of ethanol per bushel (gal/bu) (D.O.E. claims it is now 2.7 gal/bu and rising but we’ll stick to 2.5 for now).

Another U.S. Department of Agriculture Ethanol Report shows that corn stover (leaves, cobs, and stalks left over from the harvest) could add 5500 lbs of biomass per acre to ethanol feedstocks.

Using cellulosic fermentation processes, the stover could add 180 gallons of ethanol per acre to the production from the corn grains. But stover use would increase already problematic soil erosion in cornfields, which is another of the disadvantages of biomass. This feedstock must be closely managed.

Let’s put some of these numbers together and convert everything to barrels per acre of expected harvest. 2.5 gallons of ethanol per bushel at 150 bushels per acre yields 425 gallons of ethanol per acre, or about 10 barrels per acre (42 gallons per barrel). If we leave over half of the stover on the harvested field we can add about 84 gallons, or 2 barrels of ethanol per acre. That gives a total expected corn-based bioethanol harvest of about 12 barrels per acre per year.

If we assume that the 33% or so volume of distiller's grain byproduct that's left from distilling ethanol will provide an adequate supplemental feed for our nation's livestock, then we can convert the entire 80 million acres of livestock feed corn to ethanol, and expect to produce about 960 million barrels of ethanol a year.

Can we really produce almost a billion barrels of ethanol every year without adding any additional acreage or taking food from anyone’s mouth? Possibly. But corn, like lot of other crops, leaves the field devoid of vegetation for the entire winter. Barren soil produces erosion. The larger question of corn-based ethanol is how much land we can afford to expose the rigors of corn production, and for how long.

Still, a billion barrels of biofuel annually is a lot of fuel. Or is it?

According to Department of Energy – Energy Statistics , The United States of America now consumes 7.5 billion barrels of oil annually. That’s 315 billion gallons.

A billion barrels of biofuel, though it sounds like a huge amount, will reduce our oil imports by one-fourth, and our total fossil fuel consumption by less than one-seventh. It’s a good start, and before production levels reach that point fuel prices at the pump should drop significantly. But it is just a start.

How and where do we get enough biofuel to meet demand?



Continue To Disadvantages of Biomass - Part II

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