Biofuels lead growth in U.S. biomass energy

The use of energy from biomass resources in the United States grew more than 60% over the decade between 2002 and 2013 -- primarily in the form of increased use of biofuels like ethanol and biodiesel that are produced from biomass.


A fuel pump displays prices for gasoline blended with up to 10% ethanol.

According to the U.S. Energy Information Administration, biomass accounted for about half of all renewable energy consumed in 2013 and 5% of total U.S. energy consumed. The three primary sources of this biomass are wood and forest products byproducts, waste including municipal solid waste and landfill gas, and raw organic feedstocks like corn and soybean oil used to produce biofuels.

Of biomass energy resources, biofuels experienced the greatest growth over the last decade. From 2002 to 2013, biofuels created from biomass grew more than 500%, driven largely by increases in U.S. production of ethanol and biodiesel for blending as transportation fuels. These biofuels are typically produced from feedstocks such as agricultural crops and other plant material, animal byproducts, and recycled waste. For U.S. ethanol production, corn is the dominant feedstock, while biodiesel producers rely on soybean oil for just over half of feedstock needs and an array of biomass resources for the rest. Market demand for these biofuels comes in part from federal mandates such as the U.S. Environmental Protection Agency's Renewable Fuel Standard, which requires the blending of certain volumes of biofuels into gasoline and diesel.

Meanwhile, EIA data shows that consumption of wood and waste energy increased just 4% over the decade. About two-thirds of U.S. wood energy is consumed for industrial processes, while nearly all U.S. waste energy is consumed for electric generation or industrial processes.

If this trend continues, woody biomass and waste energy will continue to hold their positions in our portfolio of energy resources, while continued growth in the conversion of biomass into biofuels for transportation and other needs will increase biofuels' weighting in the nation's energy mix.  At the same time, debates continue over the cost and value of programs encouraging the growth of corn as a biofuel feedstock.  What does the future hold for biomass in the U.S.?

Energy projects installed in May 2012

A report released this week by federal energy regulators documents the composition of additions to the U.S.'s portfolio of electricity resources.  The May 2012 Energy Infrastructure Update released by the Federal Energy Regulatory Commission's Office of Energy Projects provides a summary of newly-built and expanded electric generation facilities.  This snapshot of what happened in May 2012 illustrates trends in the electric industry, including a focus on renewable energy and natural gas in project development.

According to the report, 561 megawatts of new or expanded electric generation capacity came online in May 2012.  Of this new installed capacity, the largest share -- 228 MW -- came from wind.  Most of this new capacity comes from a single project, E.ON Climate & Renewables North America, LLC’s Magic Valley Wind Farm I in Texas.  The Magic Valley I project is comprised of 112 Vestas V100 1.8-MW turbines, for a total nameplate capacity of 202 MW.

The second-largest resource class of new generation capacity in May 2012 comes from biomass, with 166 MW of new biomass capacity installed in May.  As with wind, Texas hosts the bulk of this new  capacity.  The largest new biomass project is a 100 MW wood-fired plant built in Nacogdoches County, Texas, by Southern Company, financed in part through a long-term power purchase agreement with Austin Energy to buy the power.

Solar-powered generation provides the third-largest class of capacity newly installed in May 2012.  Eleven new projects came online in May, totaling 149 MW of new capacity.  The largest of these is Enbridge Inc.’s 50 MW Silver State North Solar Project.  This project, located in Clark County, Nevada, is the first utility-scale solar facility built on federal land managed by the Bureau of Land Management.  Its output will be sold to NV Energy under a long-term PPA.

Together, these three renewable resources -- wind, biomass, and solar -- represent 543 out of the 561 MW installed in May 2012. Other fuels like coal and natural gas played a relatively minor role in terms of new capacity installed in May.  Nevertheless, the year-to-date cumulative data shows that natural gas powers the largest share of projects installed in 2012 -- 2,811 MW out of the 6,225 MW installed so far in 2012.

Torrefied wood: biomass to "biocoal"?

As society seeks improved fuels - and as forested regions seek new markets for forest products - torrefied wood or torrefied biomass is gathering interest.  Torrefaction is a roasting process in which wood or other raw biomass material is carefully heated to yield a higher-quality fuel for combustion or gasification. When combined with densification (think compressing, packing, and pelletizing), torrefied wood can be a fuel with a high energy density - and thus a high monetary value.

Trees growing in the Maine woods - is torrefaction in their future?

In torrefaction, raw wood or other biomass is typically heated to between 400 and 600 degrees F, a temperature selected to roast but not burn the material.  (Green coffee beans undergo a similar process when they are roasted.)  Wood and other raw plant material typically contains a large amount of water; this water is driven off by the torrefaction process, as are other volatile chemicals found in the raw material.  Heating also partially breaks down natural biopolymers in the wood (like cellulose, hemicellulose, and lignin), releasing even more volatiles.  The material left behind is solid, dry, and blackened: torrefied biomass.

Torrefied biomass has some advantages over raw wood as a fuel.  Because the volatile chemicals have already been driven off through torrefaction, the combustion of the biomass may have lower environmental emissions when it is finally used.  (A life-cycle analysis would take into account the volatiles driven off during torrefaction.)  Torrefied wood generally has a higher energy density than raw wood (some sources suggest 30% more), so it can be more cost-effective to transport and ship over longer distances.  This could open up more distant markets for forest products.  Torrefied biomass can also be mixed with coal to produce electricity in existing coal-fired power plants; this use, along with its dark color, has led some to call it “bio-coal”.

While torrefaction has been around for over a century, it is still in a relatively early phase in commercial use, particularly in the U.S.  What role will torrefied biomass play in the future of energy resources and forest products?

Biofuels power first commercial airline flight

Today marks the first U.S. commercial airline flight powered by biofuels.  United Airlines has selected a Boeing 737-800 for the route from Houston to Chicago.  The plane will be powered by Solajet, a fuel blend of 60 percent petroleum-based jet fuel and 40 percent biofuel produced by California-based algae producer Solazyme.


Biofuels appear poised to play an increasing role in the transportation sector.  Biofuels have traditionally included liquid fuels like ethanol (derived from corn or cellulosic sources) and biodiesel.  Biofuels typically rely on plants or algae to convert solar energy into chemicals that can be refined and modified to produce usable fuels.  The wood (biomass) burned in hearths and stoves around the world represents a very basic biofuel, but today's advanced biofuels can involve significantly more technology.  The U.S. Department of Energy is funding research and development efforts to produce "drop-in biofuels", which can be  used as additives or even replacements for liquid fuels like gasoline, diesel and jet fuels -- without requiring consumers or distributors to modify their engines and fuel distribution networks.

United Airlines is not the only carrier to take its biofuels experimentation live this week.  On Wednesday, Alaska Airlines will fly two commercial flights from its bases in Seattle and Portland, Oregon, to Washington, D.C.  Alaska Airlines' jets will be powered by a fuel blend composed of 20% biofuels from used cooking oil.  Alaska Airlines chose Dynamic Fuels as its supplier; Dynamic Fuels is a joint venture between food product giant Tyson Foods and synthetic fuel producer Syntroleum.

December 28, 2010 - a history of heating my house, and current economics

In the wake of yesterday's blizzard, I've been thinking about how we heat our homes.  At over 150 years old, my house has kept people dry and warm for quite some time.  Much of the house remains the same as it was originally, while other "new" systems like electricity and running water have been installed later in the house's history.  Its heating systems have likely been changed several times in those years.

[Photo: down by the docks on Monhegan Island, Maine.  A large cache of propane tanks rests just out of view on the right.  Propane provides a major part of Monhegan's space heating energy needs.]

When the house was built, its residents likely burned wood to keep warm.  The front room or parlor on the first floor had a fireplace, as did the bedroom above the parlor.   (These fireplaces are now bricked up, as the chimney they used is now dedicated to an oil furnace situated in the basement.)  Until 1885, wood was the dominant fuel used to heat homes in the U.S.  After 1885, wood was surpassed by coal as the dominant heating fuel in the U.S.  It isn't clear whether my house was ever heated by coal.

Today, my house has three primary heating systems: an oil furnace in the basement that feeds warm air to the first floor, a propane "decorative appliance" in the kitchen, and small amounts of electric heat (a baseboard in one room, and a portable heater).  How much does it cost for me to operate these resources?  How are my decisions affected by that cost structure?  What should I do differently?

A few data points:

The portable electric heater is rated at 1,500 W.  In one hour, it uses 1.5 kWh.  One kWh = 3,412 Btu.  Thus in one hour of maximal operation, the heater puts out 5,118 Btu of heat.  Over the past several years, I've paid an average of 15.5 cents per kWh delivered.  This means the portable electric heater costs 23.25 cents per hour of operation -- or yields 146 Btu per penny.

According to the Maine Office of Energy Independence and Security, oil in Maine is retailing for an average price of $2.98 per gallon as of 12/20/2010.  In general, a gallon of heating oil contains about 138,690 Btu.  This divides out to 465 Btu per penny assuming 100% efficiency - or 386 Btu per penny at a more realistic 83% efficiency.

The Maine OEIS reports that the statewide average for propane based on a use of 925 gallons a year is $2.74 per gallon.  Notably, a gallon of propane contains less usable energy than does a gallon of oil; a gallon of propane might contain 91,330 Btu.  This divides out to 333 Btu per penny assuming 100% efficiency.  Even assuming 80% efficiency, this yields 266 Btu per penny.

Compare wood, a fuel the house is no longer set up to burn.  Wood can be an imprecise fuel type, with great variability in both how much wood is really in a delivered cord, as well as in how many Btu are available per cord.  (It's supposed to be 128 cubic feet per cord, but in practice air spaces mean there is almost never that much wood in a cord.)  The EIA recommends a figure of 20,000,000 Btu per cord.  Prices vary widely, but $200 per cord isn't a bad price in Maine.  Using that figure, you get 1000 Btu per penny assuming 100% efficiency, or 800 Btu per penny at a more reasonable 80% efficiency.  This makes wood seem like an attractive option.

Btu per penny may not be the only factor I consider in allocating my heating burden across these fuel sources.  For example, I can set the portable electric heater up anywhere in the house, while the oil-based warm air system is permanently installed in the first floor of the house.  Wood may appear economical, but without further capital investment (in a wood stove) is unavailable as a heating source.  Still, this look at the history of the house is illustrative.  What did previous owners spend on heating?  What fuels did they use?  Do we pay more today to heat our house than they did in 1860?  Are we more comfortable today than was the house's first owner?

June 2, 2010 update - peak wood (?); more erosion on the Sandy River Road

You've heard of "Peak Oil". How about "Peak Wood"? That's the title of this interesting Miller-McCune article by John Perlin. Perlin, the author of A Forest Journey: The Story of Wood and Civilization (Amazon), notes historical examples of the depletion of wood resources (for energy, timber and habitat) leading to conquest, expansionism, and societal downfall. What do you think of his thesis?

Remember the rural road in Chesterville, Maine, that is eroding into the Sandy River? The road continues to erode.