A Northrop Grumman MQ-8B Fire Scout recently completed the first unmanned biofuel flight. The unmanned aerial vehicle (UAV) flew from an airfield in Maryland on a combination of JP-5 aviation fuel and fuel made from camelliea, a flowering plant native to Asia. The Navy says Fire Scout is the seventh and final aircraft to demonstrate the versatility of biofuel through its use in all facets of naval aviation.
U. S. Navy photo by Kelly Schindler

© 2011 Penton Media, Inc.

A physics professor at Harvard University and CEO of Carbon Engineering, Calgary, Canada, is building a machine that could pull tens of thousand of tons of carbon out of the air in an effort to reduce the amount of greenhouse gases in the atmosphere. It relies on processes developed years ago to extract small quantities of pure CO₂ for industrial purposes.

In the first step, air is blown over the air contactor which contains a cascade of a liquid that readily absorbs CO₂. (The liquid being used in the prototype is sodium hydroxide.) That CO₂-rich solution is sent to a crystallizer or causticizer where solid carbonate precipitates out and gets sent to a kiln. The kiln burns the solids at 900°C, causing them to release a stream of pure CO₂. The kiln could run on natural gas and any CO₂from burning the gas also gets sent to the contactor to prevent its release into the atmosphere. The burnt solids are pumped to a mixing tank where they react with water to reform the hydroxide solution. The solution returns to the contactor to capture more CO₂.

The kiln also generates excess heat, which the inventor wants to use to make electricity to run fans in the air contactor and mixers in the mixing tank.

The recovered CO₂ can be sold for industrial applications, permanently buried deep underground, pumped underground to make it easier to extract oil, or used to make hydrocarbon fuels with lower life-cycle carbon emissions than gasoline. It is hoped that a company could make money by selling the CO₂ the machine removes from the atmosphere.

© 2011 Penton Media, Inc.

The U. S. government‘s Renewable Fuel Standard mandates that by 2022, the U. S. use 15 billion gallons of corn-based ethanol, 1 billion gallons of biodiesel, and 16 billion gallons of cellulosic fuels. A recent peer-reviewed report from the National Academy of Science prepared for Congress concludes that the goals for corn-based ethanol and biodiesel can be met, but those for cellulosic fuels are probably unreachable.

“The U. S. has more than 200 plants that convert corn into more than 14 billion gallons of ethanol and it took more than 30 years to get to this point,” says Wally Tyner, a professor of agricultural economics at Purdue and cochair of the committee that wrote the report. “We have only 11 years to reach even higher numbers for cellulosic biofuels. Therefore, to reach the goal, we would need to build refineries at three times the rate we built refineries for corn ethanol. And with corn, we had the technology, we had the feedstock, and prices for corn were relatively low. We don’t have any of that with cellulosic.”

For example, there are currently no refineries that can turn cellulosic feedstock into ethanol. And the amount farmers would have to be paid to earn a profit raising cellulosic materials is more than ethanol producers are willing to pay. There are also questions about the environmental effect of growing the needed materials because additional land would need to be put under cultivation, a process that releases greenhouse gases. According to Tyner, what it would take to meet the mandate is a major technological breakthrough, a substantial increase in the price of oil, or an increase in subsidies for cellulosic-ethanol producers.

© 2011 Penton Media, Inc.

The National Nano Device Lab in Taiwan has developed a manufacturing process that can build integrated circuits combining a two-sided solar cell and thin-film transistors (TFTs). The underlying process is said to be environment-friendly and is billed as a step toward self-powered chips.

One side of the resulting chip features both a solar cell and TFTs made from CIGS (CuInGaSe2). These devices are on the back of a silicon-based solar cell. The chips are made without using environmentally harmful cadmium, or sodium, which is typically found in CIGS solar-cells. Cells often incorporate these materials to boost light conversion efficiency. To compensate, the CIGS layer was deposited on a textured surface, bringing the CIGS cell conversion efficiency up to 11%.

The TFTs set a record for CIGS technology, demonstrating a hole mobility of 0.22 cm2/V. The relatively low-temperature (400 to 500°C) and sodium-free manufacturing process used could make the CIGS fabrication technique compatible with CMOS processing.

The researchers will describe their work at the upcoming IEEE International Electron Devices Meeting (IEDM) in Washington, D. C., in December (“Bifacial CIGS [11% Efficiency]/Si Solar Cells By Cd-Free And Sodium-Free Green Process Integrated With CIGS TFTs,”).

© 2011 Penton Media, Inc.

The Dept. of Energy recently funded a project with Advanced Magnet Lab, Palm Beach, Fla., to develop a superconducting direct-drive generator for large wind turbines. The generator will use superconducting wires in the windings and be cryogenically cooled. This will eliminate the need for a gearbox, one of the turbine’s heaviest components, which usually must be lifted by crane into the turbine nacelle. Eliminating the gearbox could let smaller turbines generate as much power as larger units because higher turbine power ratings traditionally have demanded bigger gearboxes.
And superconductive wiring will lead to smaller, lighter generators. The zero-resistance wirings should boost efficiency and make for more-reliable generators, once cryogenic issues are properly addressed. The company will work with engineers at Argonne National Laboratory who have experience in cryogenics and large-scale simulations.

© 2011 Penton Media, Inc.

The design of a solar-powered trash compactor for city streets used several plastic-molding issues to make it practical.

The original compactor made by BigBelly Solar in Needham, Mass., worked well but was costly to manufacture. The Mack Molding Co. in Arlington, Vt., worked with BigBelly to address the cost problems.

To shield the solar panel from the elements, Mack injection molds a clear cover from high-impact, UV-resistant polycarbonate resin on a 1,000-ton press. The large part must be perfectly clear to expose the solar panel below to the sun. The 27.75 × 20.39 × 4.39-in. part is molded with just one gate to avoid knit lines that would interfere with sunlight hitting the solar cells.

Mack also compression-molds side panels and a hopper cover from thermoplastic olefin that has been 100% recycled from car bumpers. Wall thicknesses vary and the side walls are thinner than the main wall. The molding gate was located on the thinner side wall so that it is invisible after assembly.

Mack conducted mold-flow analysis, as well as experiments with tooling, to set cycle time, temperature, and injection pressure. It finalized a mold that would give technicians more control over the process. The tool design was also critical in terms of the location and direction of water lines. Engineers were able to downsize the tool by using a hot runner bar, which lets the part run in a smaller press with better economics.

The trash bin in the compactor is rotomolded of low-density polyethylene resin. Mack fabricates the back panel and door out of metal. The unit can be custom painted, silk-screened with logos or other artwork, or vinyl wrapped with custom artwork.

The point of equipping these trash receptacles with solar power is to let service personnel make fewer stops to empty its 32-gallon bin. The solar cells charge a battery which provides all the power needed to periodically compact trash. Thus, the receptacle can sit anywhere because it needn’t plug in to outside power. As trash accumulates, an internal photoelectric cell senses when the bin is full and triggers a compaction cycle. When the receptacle needs to be emptied, it sends a text message via wireless link to a pickup crew.

Typical users of the trash bin include national parks, beaches, universities, towns, and major cities. The city of Philadelphia, for example, replaced 700 ordinary receptacles with 500 solar-powered trash compactors and 210 single-stream recycling units. The city now collects trash only five times per week instead of 17. Collection takes nine workers on one shift instead of 33 on three shifts, as was formerly the case.

© 2011 Penton Media, Inc.

Lawrence Livermore National Laboratory and the Clean Energy Research Institute in China recently agreed to collaborate on R&D for clean energy. The institute is the research wing of Huaneng Power International Inc., the world’s largest power company. The two organizations will concentrate on carbon capture and sequestration (CCS), enhanced oil recovery, and shale gas.
Livermore scientists will contribute their expertise in CCS, material science, and energy-systems analysis. Huaneng operates GreenGen, the first large-scale coal-fueled power plant that uses CCS. The company also operates the largest CCS pilot plant. That plant uses 15 MW to capture about 120,000 tons of CO₂ annually. The company plans on scaling up CCS at the plant so it can sequester 2.5 million tons of CO₂ per year.

CCS separates CO₂ from the flue stream of industrial and power plants, compresses it, and stores it underground in deep geological formations, thus preventing it from entering the atmosphere.

© 2011 Penton Media, Inc.

Engineers and nuclear scientists have a host of challenges to overcome before they build a working model of a tokamak, a fusion-powered reactor that could generate 10 times the power of a conventional fission reactor using fuel derived from seawater. One problem is constructing reactor walls and coatings that stand up to interactions with the plasma contained within. These plasmas can reach 100 million degrees Celsius, hot enough to physically change materials they come near.

To help surmount that challenge, engineering students at Purdue University, led by professor Jean Paul Allain, constructed a materials analysis particle probe, or MAPP. MAPP will collect information on how materials change when exposed to plasmas and how those interactions correlate with changes in the plasmas. It is hoped this data will lead researchers to materials that can line tokamak reactors.

MAPP will be used on the experimental reactor at Princeton University, the country’s largest spherical tokamak, known as the National Spherical Torus Experiment. The new device replaces the previous investigational method of lining inner reactor walls with test specimens of materials that are removed and checked after a year of operation and hundreds of tokamak experiments. MAPP will let researchers see results and changes in materials just minutes after each experiment. The new probe will also let scientists from anywhere in the world program and use it through a Web site based at Purdue.

© 2011 Penton Media, Inc.

A 75-ft-high tidal turbine will include a custom-designed brake to prevent overspeeding and eliminate shock loads that could damage the novel power-generating device.

Last August, the Atlantis AK-1000 turbine, the world’s largest single-axis tidal turbine to date, was installed at the European Marine Energy Centre in Scotland for testing. Designed by Atlantis Resources Corp. in the U. K, the turbine contains twin rotors 59 ft (18 m) in diameter that harness ebb and flow tides to generate 1 MW of power. These horizontal-axis turbines sit on the ocean floor, in what is considered to be the harshest environment on the planet.

The turbine’s need for a large-capacity braking system eventually led to the use of a wet, multiplate marine turbine brake from Wichita Clutch in the U. K. The Wichita HBS 42-14 clutch installs on the rotor (low-speed) shaft. The unit’s wet-brake technology uses oil shear to generate the braking torque and does not create dust or debris as would a dry-friction brake. Because brake torque transmits through the shearing of the oil film, friction plates never actually touch until relative velocity approaches zero; consequently there is little wear.

For this environmentally sensitive project, Wichita tested and approved the use of a biodegradable synthetic oil as a safer alternative to traditional hydraulic oils. And because the turbine rotors turn at just 6 to 8 rpm, studies indicate the units present little hazard to marine life.

The rugged HBS 42-14 has a dynamic torque capacity of 1.2 MNm and was custom designed to suit the Atlantis parameters for braking torque, controlled and emergency stops, condition monitoring, nacelle mounting, and shaft sealing. It also incorporates a custom hydraulic power pack which provides proportional braking control under normal circumstances and a fast-approach, soft-braking feature in the event of total power loss.

The brake sits inside a dry nacelle. The main shaft, brake, and generator reside in a sealed tube at normal atmospheric pressure. Although not required on the Atlantis turbine, the Wichita brake is capable of full submersion and could be used in a pressurized environment (typical depth 100 ft).

© 2011 Penton Media, Inc.

Boiler rooms are hot places, with air near the ceiling at about 120°F in the summer and 90°F in the winter. To use that otherwise wasted heat, inventor Bob Biancardi developed what he calls the Geo-Wasted Thermal Energy Recovery System (Geo- WTERS). It consists of a heat exchanger and fan. Hospitals, factories, schools, and any organizations that use boilers can install the 130-lb device to save money on fuel and keep the boiler room cooler.

The 21 × 21 × 4-in. device is installed on the piping that sends make-up water into the boiler. (This water can be as cold as 40°F in the winter.) Make-up water replaces water lost in the boiler’s pipes. Returning water, or condensate is already heated and is returned to the boiler. So only about 20 gpm of water needs to flow through the heat exchanger. This lets the device be used on boilers rated from 200 to 900 hp. If more make-up water needs to be preheated, two or more Geo-WTERS can be used. And one unit can be plumbed to serve up to three boilers.

© 2011 Penton Media, Inc.