News

April 5, 2013

Sandia offers world a fertilizer that fizzles as a bomb

BOMB-PROOFING FERTILIZER — Chemical engineer Vicki Chavez (6633) worked with now-retired Kevin Fleming to prove that iron sulfate mixed with ammonium nitrate could produce a non-detonable fertilizer. (Photo by Randy Montoya)

by Nancy Salem

Ammonium nitrate is an essential fertilizer, high in nitrogen and a staple of the agricultural industry. But it has a dark side.

The raw ingredient in about 75 percent of the improvised explosive devices (IEDs) in Afghanistan is ammonium nitrate, according to US government reports. The fertilizer is illegal in Afghanistan but legal in neighboring Pakistan, where a quarter of the GDP and half the workforce depend on agriculture.

During Afghanistan’s 11-year war, IEDs have killed more American troops than any other weapon. About 1,900 troops were killed or wounded in IED attacks in 2012, 60 percent of American combat casualties. Ammonium nitrate was used in about 16,000 bombs in Afghanistan in 2012, up 200 percent since 2008, according to government reports.

US efforts to curb the flow of the fertilizer into Afghanistan through seizures, export controls, and diplomacy have had limited success.

Kevin Fleming, a Sandia optical engineer who also did counter-IED training for the military, took a different approach. He has developed a fertilizer formula as good as, if not better, than ammonium nitrate, but not detonable. And Kevin, with the support of Sandia officials, decided not to patent or license the formula, but to make it freely available in hopes of saving lives.

An Achilles Heel

“I looked at it differently,” says Kevin, who retired from the Labs in February. “I’ve been an organic gardener since I was 8. We had five acres in Las Cruces with the problems of calcareous soils that are very similar to those in the Middle East. I know something about commercial farming.”

He also knew the chemistry of IEDs from years of training soldiers how to deal with them.

Ammonium nitrate has an Achilles heel from a terrorist’s perspective. The ammonium ion is weakly attached to the nitrate ion. They hang onto each other, but the right chemical reaction can easily pull them apart. Kevin reasoned you could separate the ions by adding a compound they would rather cling to, called a metathesis reaction. “It would change into something else at the molecular level,” Kevin says.

He tried several materials including iron sulfate, a readily available compound that steel foundries throw away by the tons. When mixed with ammonium nitrate, the iron ion “grabs” the nitrate and the ammonium ion takes the sulfate ion. Iron sulfate becomes iron nitrate and ammonium nitrate becomes ammonium sulfate. This reaction occurs if people attempt to alter the fertilizer to make it detonable when mixed with a fuel.

“The ions would rather be with different partners,” Kevin says. “The iron looks at the ammonium nitrate and says, ‘Can I have your nitrate rather than my sulfate?’ and the ammonium nitrate says, ‘I like sulfate, so I’ll trade you.’”

Ammonium sulfate and iron nitrate are not detonable, even when mixed with a fuel. “It’s a different compound,” says Kevin, who completed work on the formula in late 2012. “At the chemical level it’s a great fertilizer but does not detonate.”

Chemical engineer Vicki Chavez (6633) ran a small-scale proof-of-concept of the reaction, and validated it. “We were able to prove that there was little to no ammonium nitrate left in the resulting process,” she says. “It was very cool. We looked at pure ammonium nitrate and pure ammonium sulfate. The resulting sample looked more like ammonium sulfate.”

Kevin says iron sulfate in fertilizer adds iron and acidifies soil. “It does good things for soil health. It takes alkaline soil and makes it more neutral, closer to an ideal pH level,” he says. “The closer you get a neutral pH, the more crops grow. Crop yield would improve significantly.

“And iron-containing fertilizer added to the soil would be taken up in crops and help fight anemia and other iron deficiencies in people who eat them.”

The soil in Afghanistan is alkaline with a high pH, and could benefit from an ammonium nitrate/iron sulfate fertilizer, Kevin says. “What they use now, ammonium nitrate with calcium carbonate — which makes soil more alkaline — doesn’t make sense,” he says.

Danger to soldiers

Sandia could have patented the formula but opted to waive ownership rights for humanitarian reasons.

“One of Sandia’s priorities is deploying the technologies that result from our research for the public good,” says Pete Atherton, senior manager of Industry Partnerships Dept. 7930. “In this case, we believe that making it freely accessible and disseminating it as widely as possible was the best way to accomplish this mission.”

Replacing ammonium nitrate with a non-detonable fertilizer in Afghanistan and other parts of the world will not happen overnight, Kevin says. Ammonium nitrate is produced in huge plants in many locations. “It’s easy to get in large quantities,” he says. “The sheer volume of ammonium nitrate is gigantic.”

But he says there are some thoughts on how to get the non-detonable formula into the marketplace. “We could give the formula to a neutral party and let them work with the Afghanis, Pakistanis, and others,” he says. “They could set up side-by-side demonstrations to see which fertilizer works better. Prove it to them gradually.”

Kevin says his sense of urgency in tackling the issue came from looking into the eyes of hundreds of soldiers he trained in anti-IED tactics. “Explosive Ordnance Disposal techs see a lot of IEDs, and about one third of them will die, be maimed, or injured by IEDs before getting through their tours, and most from ammonium nitrate-based explosives,” he says.

At a meeting last year in Crystal City, Va., Kevin sat next to an ex-Marine who had lost both legs trying to find IEDs. “He had a metal detector, but some bombs are chemically initiated with no metal parts. He stepped on a non-metal trigger and set off a blast that took off both legs. He became a double amputee in milliseconds. So when I sit next to him and see the aftermath of an IED, I have to think of any way possible to keep stuff like this from happening.” 

-- Nancy Salem

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Sandians kick off Manos program for Hispanic youth

Salvador “Sal” Rodriguez (1532) works with a student during the inaugural session of this year's Manos program. (Photo by Randy Montoya)

by Stephanie Hobby

Last week, more than 140 Hispanic middle school students embarked on a four-week-long academic adventure designed to encourage students’ interest in math, science, and engineering concepts. The Manos program was launched by Sandia’s Hispanic Leadership Outreach Committee and Community Involvement Dept. 3652 in partnership with Albuquerque Public Schools. Manos is now in its 23rd year.

Twice a week, after school, students from several area middle schools board buses and head to Rio Grande High School for two-hour workshops. Students select one of seven workshops focused on physics, chemistry, electronics, computer design, robotics, finances, and introduction to engineering. Activities include building and flying rockets, learning what causes fireworks to have different colors and what makes bread rise, circuitry and controlling the flow of electricity, building web pages, building and programming LEGO robots, making money “grow,” and building cars and bridges.

Miquelita Carrion (10657) leads the coordination of Manos, and all of the teachers are Sandia employees who volunteer their time. The participating middle schools are Ernie Pyle, Polk, Harrison, Truman, John Adams, and Jimmy Carter.

“We really want to increase the pool of Hispanic students who pursue STEM university degrees by showing students the possibilities and highlighting the accomplishments made by Hispanic professionals,” says Javier Ruiz (10657), who helps coordinate the Manos program. “One of our goals is to increase and promote academic excellence for students at the precollege level. We provide hands-on learning experiences to help inspire these young minds, and to see them succeed is very rewarding.”

-- Stephanie Hobby

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Computer model used in softening steel

Lisa Deibler (1819) holds a tubing specimen in a grip, ready to load it into the thermal-mechanical experimental system behind her. Lisa of Sandia/New Mexico and Arthur Brown (8259) of Sandia/California worked together to develop a simulation for an annealing process to soften tubing that was too hard for the requirements of the job. (Photo by Randy Montoya)

by Sue Major Holmes

Sandia researchers Lisa Deibler and Arthur Brown had a ready-made problem for their computer modeling work when they partnered with NNSA’s Kansas City Plant to improve stainless steel tubing that was too hard to meet nuclear weapon requirements.

When steel is too hard it becomes brittle, so the plant ended up getting new tubing. However, Lisa says KCP needed a backup in case it couldn’t find replacements in time to meet deadlines.

Sandia’s modeling, coupled with experiments, allowed the rapid design of an annealing process to soften the tubing while keeping the metal’s desired structure. The model predicted how the microstructure would be affected by variations in the process, which improved researchers’ confidence that the heat treatment would produce parts that met specifications.

Arthur (8259), a modeler at Sandia/California, says working on the model was a natural extension of a larger project, supported by Sandia’s Nuclear Weapons program, called Predicting Performance Margins. Under that program, numerous Sandia researchers are studying the way microstructure affects properties of materials at various scales. Arthur became involved in the project as a member of a team that developed a thermal-mechanical modeling tool to predict how microstructure and properties change during forging. That led to his collaboration with Lisa and her technical adviser, Joe Puskar (1831), on thermal profiles for welds.

When the need arose to address the tubing issue, Arthur says Joe contacted him to see if Arthur could work with Lisa to help optimize a heat treatment.

Experiments, modeling work together

Lisa, a post-doc in Sandia/New Mexico’s Materials Characterization and Performance Department, provided experimental data that Arthur fed into his model of recrystallization in stainless steel. Recrystallization, in which grains in deformed microstructures are replaced by strain-free grains, occurs during annealing — the process of heating metal to dissipate energy built up while the metal is compressed, twisted, or otherwise worked. Heat makes the metal softer and more ductile.

Lisa and Arthur were able to solve the plant’s real-life problem since recrystallization is part of the annealing process. And they were able to do it quickly because the model already existed.

Lisa’s experiments indicated it was important to model two softening mechanisms, recovery and recrystallization. Recovery occurs first within a microstructure when material is heated to soften it. By measuring the hardness and the amount of recrystallization after each heat treatment, Arthur and Lisa identified how much softening was due to recovery.

 “It was important to model both softening mechanisms because we were seeing microstructures that contained no new recrystallized grains, but which had changed properties from the initial deformed material,” Lisa says. “By failing to include the effects of recovery, our model couldn’t predict why the properties weren’t the same as the initial deformed material. Adding in recovery allowed us to account for the changed properties in microstructures with no recrystallization.”

She described the work in a poster, “Design of a Heat Treatment to Soften Stainless Steel Tubing,” presented at Sandia’s winter 2012 Post-Doctoral Technical Showcase.

Solution required baseline for model

The team first developed a baseline for the model. Lisa performed heat experiments on the steel tubing since she didn’t know the conditions under which it was manufactured. That effort required “a lot of shipping tubing around the country for various heat treatments,” she recalled.

She put tubing samples in Sandia’s thermal-mechanical experimental system at various temperatures for different lengths of time. Then she had the tubing sectioned, polished, and etched, and analyzed the images to see how much the microstructures had recrystallized. Arthur fit her data with the model to simulate different heat treatments.

The simulation also required knowing something about the furnace where the tubing would be softened. Heating a furnace quickly tends to overshoot the desired temperature, so the team used the model to determine whether it was better to heat the furnace quickly or slowly raise it to the correct temperature, Lisa says. Once Arthur identified the optimal rate of increase and other factors, KCP technicians filled a furnace with tubing and measured the temperature at several locations inside. Arthur then ran those profiles through the model, which allowed him to predict the impact of temperature variations on the tubing’s final properties.

Looking ahead

The researchers want the model to handle both forging and welding because in some ways the two pro-cesses work against one another. Forging steel gives it a strong microstructure, but welding adds heat that can destroy those properties. “So if you were able to model that process, that would provide a lot more confidence in the overall modeling that their parts aren’t going to fail,” Lisa says.

In the future, the researchers want to use the model for all kinds of welding at Sandia: laser welding, resistance welding, and gas tungsten arc welding. Types of welding vary in their thermal rates — how fast something is heated.

“Looking at how different heating and cooling rates affect the microstructure during welding would give us valuable information,” Lisa says.

-- Sue Major Holmes

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Maritime ports may be the next deployment for hydrogen fuel cells

Auxiliary power through a hydrogen fuel cell may soon be piloted on the intra-island transport barge system in Hawaii. The fuel cell will replace the diesel generators used to supply power to containers on the barge.

by Patti Koning

Hydrogen fuel cells may be heading out to sea in the not-too-distant future. Hydrogen fuel cells are being used in a variety of ways to provide efficient, pollution-free power — mobile lighting systems, forklifts, emergency backup systems, and light duty trucks, to name a few. Providing auxiliary power to ships in berth may be added to that list soon.

Joe Pratt (8366) and Aaron Harris (8367) recently completed a study for DOE’s Office of Energy Efficiency and Renewable Energy that found hydrogen fuel cells may be both technically feasible and commercially attractive as a strategy for providing power to ships at berth and replacing on-board diesel generators.

Auxiliary power to stationary ships in port, usually provided by on-board diesel engines, is a significant contributor to greenhouse gas emissions and air pollution, accounting for one-third to one-half of the in-port emissions attributed to ocean-going vessels. For a busy place like the Port of Los Angeles, those average daily emissions could exceed that of nearly 200,000 vehicles, according to the paper “Harboring Pollution — Strategies to Clean Up U.S. Ports,” by D. Bailey, T. Plenys, G. M. Solomon, T. R. Campbell, G. R. Feuer, J. Masters, and B. Tonkonogy, published by National Resources Defense Council, N.Y., August 2004.

Fuel cell strategy

The fuel cell strategy is simple — a hydrogen-fueled proton exchange membrane (PEM) fuel cell mounted on a floating barge. Supplying a container ship with average power and run times (1.4 megawatts over 48 hours) requires four 40-foot containers, two for the fuel cell and two for the hydrogen storage, which could readily fit on a typical flat-top barge. For ships requiring less power, like a tugboat, a single container housing both the fuel cell and hydrogen will suffice.

To evaluate the feasibility of this strategy and analyze potential deployment options, Joe visited ports along the West Coast and in Hawaii. He gathered data from two Department of Transportation Maritime Administration MARAD facilities and the ports of Long Beach, Los Angeles, Oakland, Portland, Tacoma, Honolulu, and Seattle.

“While Sandia has previously examined the potential for hydrogen and fuel cells in aircraft, construction equipment, electrical generators, telecom backup, man-portable power, and mobile lighting systems, this is the first study of a maritime environment,” he says. “During the course of this study I learned what complex and amazing places ports are, with so much activity and so much variety between the individual ports.”

An alternative to auxiliary diesel engines is a practice called “cold-ironing,” in which a vessel at berth connects to a source of electricity on the shore. The engine, made of steel or iron, literally becomes cold, hence the name. Electricity supplied by a hydrogen fuel cell can be another form of cold-ironing.

Grid-based cold-ironing

The Navy has been employing grid-based cold-ironing for many years to save fuel. California is now turning to the practice to meet the state’s tough environmental regulations. While only a few berths have grid-based cold-ironing, infrastructure is being installed at ports across the state to meet California Air Resources Board regulations that take effect in 2014.

Grid-based cold-ironing is complex and costly to implement, as most ports lack the necessary infrastructure to meet the power needs of multiple ships at berth. Those costs can run to $5-$10 million or more per berth. The Port of Oakland is installing 11 berths on six terminals at an estimated cost of about $70 million.

In addition, switching to grid-based power doesn’t eliminate emissions. Instead, this approach shifts the emissions to the source of electricity. Depending on the electricity source, the overall reduction in emissions can be quite small.

The hydrogen fuel cell barge bypasses the need for electrical infrastructure. The barge also has the potential for higher usage because it can be moved from berth to berth as needed and to anchorage points to power vessels waiting for berths.

“In California, ports are already installing the necessary infrastructure for cold-ironing because of the regulations introduced a few years ago,” says Joe. “So the need for hydrogen fuel cell auxiliary power isn’t there. While this was an unexpected finding, we discovered other locations and applications for hydrogen fuel cell power.”

At ports in Oregon and Washington, grid-based cold ironing infrastructure is limited or nonexistent. Using a hydrogen fuel cell for powering container ships at berth has attracted interest for the potential economic and environmental benefits. Joe continues to work with those ports on quantifying the benefits and deployment options.

In Hawaii’s Honolulu Harbor in Oahu, a different need was found. Much of the cargo is unloaded and then reloaded onto barges for distribution to the other islands. As the barges have no power, they carry diesel generators to provide power to shipping containers that require refrigeration, known as “reefers.”

“You can replace the diesel generator with a hydrogen fuel cell without changing the operations. It’s just a power source in a box, a shipping container in this case,” says Joe. Hawaii ports aren’t facing the same strict regulation of emissions as California ports, but the potential savings in fuel cost is attractive for the company operating the inter-island transportation service, along with anyone else suffering from high fuel expenses.

Basic fuel cost analysis

The study’s basic fuel cost analysis showed that hydrogen at about $4 per kilogram with a fuel cell can break even with maritime fuels at today’s prices with a combustion engine. Subsequent analysis has shown that when generators are frequently producing less than maximum power (part load operation), such as

in the Hawaii application, the efficiency difference between the fuel cell and combustion engine is widened. Even hydrogen at $5 per kilogram can potentially save tens of thousands of dollars per year for each generator.

“Fuel cost is only part of the total economic picture, but discovering that the cost-effective hydrogen price matches that which is expected to be available is an important finding,” says Joe.

            He is now developing a detailed plan for the Hawaiian inter-island transport barge application. “A successful deployment of the containerized fuel cell on a floating platform in a typical marine environment will be useful not only in this particular service, but also because it validates the concept for the larger, container-ship sized application,” he says. “It’s challenging on many levels, but technically feasible with potential commercial and worldwide impact.”

-- Patti Koning

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