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Archive → May, 2010

Burning Biofuels

The biofuels industry has had to confront some baggage lately. Crops for fuels might require land that would otherwise be used to grow food, and take up precious water and petroleum-derived fertilizers. When biomass is burned in order to convert, say tropical forest into a biofuel crop, such as oil palm, the CO2 balance can get out of hand.

Corn cobs to be used for cellulosic ethanol production. Credit: Poet

Nevertheless, optimal examples of biofuels such as cellulosic ethanol (especially when derived from agricultural wastes) and high energy biobutanol are generally considered to have large climate advantages over petroleum fuels.

Now a research team led by Katharina Kohse-Höinghaus, of the Department of Chemistry, Bielefeld University in Germany, have published a review paper in Angewandte Chemie

to explore what is known about what happens when we burn biofuels.

Of course there is no such thing as a free lunch – when we burn biofuels in a car we are still engaging in combustion, and the products of that combustion — other than heat and getting the car moving — are going to go into the air. Common biofuels are oxygenated, which suggests they will burn differently compared to fossil fuels. Kohse-Höinghaus points out that 1) we should  study what the products of biofuels combustion (and resulting pollution) really are and 2) we should use this knowledge along with other more well-understood criteria to decide which biofuels should receive policy support.

The authors review the available research and provide some broad-brush insights (in addition to many specifics). Biofuels can produce polycyclic aromatic hydrocarbons (PAHs) and soot, just like conventional hydrocarbons, though often in lower amounts. But that benefit is paid for by increased output of carbonyl compounds, including formaldehyde, acetaldehyde, acetone, and higher aldehydes and ketones.

A  wild card for biofuel combustion is possible emissions of NOx molecules, depending on how much nitrogen is present in the biofuel. Another unknown is what happens with mixtures of fossil fuels and biofuels, such as petroleum diesel and biodiesel.

Recently, the controversial concept of indirect land use was applied to the renewable fuels standard in the U.S. (now in its second edition). Perhaps when RFS3 is being debated, we’ll have a firmer grasp on which biofuels burn cleanest.

More Chemistry Aids Gulf Cleanup

C&EN recently took a closer look at the chemical dispersants being used to clean up the Deepwater Horizon oil spill. In the current state-of-the-art application, the team, led by BP, is pumping Nalco’s dispersant about a mile underwater, at the site of the leak.

Late yesterday afternoon, EPA Administrator Lisa Jackson reported that the effort overall has used 430,000 gallons of dispersants, and has ordered over 800,000 gallons more.

Meanwhile, my colleague Lauren Wolf brought to my attention another substance that is being used in a somewhat more limited fashion in an effort to gather up oil before it reaches shore on Dauphin Island, AL.

The product, called C.I.Agent, made by C.I.Agent Solutions, is described by the company as an environmentally-friendly and non-toxic blend of petroleum-based polymers.  In a video posted on the firm’s website, C.I.Agent looks like a white powder. The video shows the powder sticking to liquid diesel fuel and turning it into a soft, plasticy mass that can then be removed from water.

The material is being given a trial run off the Gulf coast as part of a beach-protecting bunker system. A reporter-blogger from the LA Times was on the scene on Dauphin Island and posted a report with photos.

Hair and Stockings Help Gulf Cleanup

My colleage Lisa Jarvis tipped me off that NPR’s All Things Considered is featuring a story about a tried-and-true oil containment boom technology -  nylon stockings stuffed with human hair. An organization that works with hair salons (and obtains nylons from helpful transvestites) is sending 400,000 lbs of hair to the Gulf to help with the cleanup.  

Another unusual use for human hair appeared recently in C&EN. I wonder if there are others…

Gulf Clean-up: Breaking down oil with surfactants

Cleantech Chemistry will save for later the discussion of whether the environmental disaster in the Gulf of Mexico will put more attention on replacing petroleum in the U.S. economy. But in the meantime it is interesting to note the contribution that chemistry is making to clean-up efforts.

Water treatment firm Nalco released a statement confirming that it is supplying quantities of oil dispersants for the Gulf operation, but did not elaborate on how much of it the company was selling. Nevertheless, the announcement prompted Nalco’s stock to rise 18% to $29.25, hitting its highest point since October 2007. In the press release, Nalco thanks its suppliers for stepping up to the plate, which suggests the company is selling its dispersant as fast as it can be manufactured.

Though Nalco has not yet responded to a request for an interview, the company’s website describes its Corexit dispersant technology as designed specifically to protect and clean shorelines affected by oil spills at sea. The product is made with bio-degradable surfactants in a low-toxicity, de-aromatized hydrocarbon solvent system.

If the chemical dispersant works as designed, the solvent system distributes the surfactants into the oil slick. Then the surfactants go to work reducing the surface tension at the oil/water interface. With the oil film’s cohesion lessened, the action of the waves helps to break up the slick into small droplets of oil. The small drops sink from the surface of the sea and are further degraded by the ocean’s native bacteria.

BP CEO Tony Hayward has been reported as claiming the dispersants have had a significant impact keeping the oil from floating to the surface, but there is very little detail available about how successful the chemical treatment has been so far.

In addition to  Nalco, other producers of dispersants include BP, Croda, Dasic International, INEOS Chemical, Shell, Taiho, Total, and U.S. Polychemical, writes Laurence Alexander, chemicals analyst at Jefferies & Company. Alexander has been tracking reports that the operation is requiring around 10,000 gallons of dispersants a day.