Sunday, December 13, 2009

Bacteria Engineered to Turn Carbon Dioxide Into Liquid Fuel

ScienceDaily (Dec. 11, 2009) — Global climate change has prompted efforts to drastically reduce emissions of carbon dioxide, a greenhouse gas produced by burning fossil fuels.

Genetically engineered strains of the cyanobacterium Synechococcus elongatus in a Petri dish. (Credit: Image courtesy of University of California - Los Angeles)

In a new approach, researchers from the UCLA Henry Samueli School of Engineering and Applied Science have genetically modified a cyanobacterium to consume carbon dioxide and produce the liquid fuel isobutanol, which holds great potential as a gasoline alternative. The reaction is powered directly by energy from sunlight, through photosynthesis.

The research appears in the Dec. 9 print edition of the journal Nature Biotechnology and is available online.

This new method has two advantages for the long-term, global-scale goal of achieving a cleaner and greener energy economy, the researchers say. First, it recycles carbon dioxide, reducing greenhouse gas emissions resulting from the burning of fossil fuels. Second, it uses solar energy to convert the carbon dioxide into a liquid fuel that can be used in the existing energy infrastructure, including in most automobiles.

While other alternatives to gasoline include deriving biofuels from plants or from algae, both of these processes require several intermediate steps before refinement into usable fuels.

"This new approach avoids the need for biomass deconstruction, either in the case of cellulosic biomass or algal biomass, which is a major economic barrier for biofuel production," said team leader James C. Liao, Chancellor's Professor of Chemical and Biomolecular Engineering at UCLA and associate director of the UCLA-Department of Energy Institute for Genomics and Proteomics. "Therefore, this is potentially much more efficient and less expensive than the current approach."

Using the cyanobacterium Synechoccus elongatus, researchers first genetically increased the quantity of the carbon dioxide-fixing enzyme RuBisCO. Then they spliced genes from other microorganisms to engineer a strain that intakes carbon dioxide and sunlight and produces isobutyraldehyde gas. The low boiling point and high vapor pressure of the gas allows it to easily be stripped from the system.

The engineered bacteria can produce isobutanol directly, but researchers say it is currently easier to use an existing and relatively inexpensive chemical catalysis process to convert isobutyraldehyde gas to isobutanol, as well as other useful petroleum-based products.

In addition to Liao, the research team included lead author Shota Atsumi, a former UCLA postdoctoral scholar now on the UC Davis faculty, and UCLA postdoctoral scholar Wendy Higashide.

An ideal place for this system would be next to existing power plants that emit carbon dioxide, the researchers say, potentially allowing the greenhouse gas to be captured and directly recycled into liquid fuel.

"We are continuing to improve the rate and yield of the production," Liao said. "Other obstacles include the efficiency of light distribution and reduction of bioreactor cost. We are working on solutions to these problems."

The research was supported in part by a grant from the U.S. Department of Energy.

Tuesday, December 8, 2009

Breakthrough in 'Spintronics' Could Lead to Energy Efficient Chips

Silicon spin sandwich. (Credit: Image courtesy of University of Twente)
ScienceDaily (Dec. 7, 2009)
— Scientists from the MESA Institute for Nanotechnology of the University of Twente and the FOM Foundation have succeeded in transferring magnetic information directly into a semiconductor. For the first time, this is achieved at room temperature. This breakthrough brings the development of a more energy efficient form of electronics, so-called 'spintronics' within reach. The results are published on November 26 in Nature.

So far, information exchange between a magnetic material and a semiconductor was only possible at very low temperature. The successful demonstration of information exchange at room temperature is a pivotal step in the development of an alternative paradigm for electronics. The main advantage of this new 'spintronics' technology is the reduced power consumption: in present-day computer chips, excessive heat production is already a problem, and this will soon become a limiting factor.

Digital by nature

Unlike conventional electronics that employs the charge of the electron and its transport, spintronics exploits another important property of the electron, namely the 'spin'. The sense of rotation of an electron is represented by a spin that either points up or down. In magnetic materials, the spin orientation can be used to store a bit of information as a '1' or a '0'. The challenge is to transfer this spin information to a semiconductor, such that the information can be processed in new spin-based electronic components. These are expected to operate at lower power consumption, since computations such as reversing the electron spin, require less power than the usual transport of charge.

Only a few atomic layers thick

To achieve an efficient information exchange, the researchers insert an ultra thin -- less than one nanometer thick -- layer of aluminum oxide between the magnetic material and the semiconductor: this corresponds to only a few atomic layers. The thickness and quality of this layer are crucial. The information is transferred by applying an electric current across the oxide interface, thereby introducing a magnetization in the semiconductor, with a controllable magnitude and orientation.

Importantly, the method works for silicon: the prevalent electronic material for which highly advanced fabrication technology is available. The researchers found that the spin information can propagate into the silicon to a depth of several hundred nanometers. This is sufficient for the operation of nanoscale spintronic components, according to researcher Ron Jansen. Now the next step is: to built new electronic components and circuits and use these to manipulate spin information.

The spintronics research is performed by a team of researchers led by Ron Jansen at the MESA+ Institute for Nanotechnology, and is made possible by financial support from the Foundation FOM and a VIDI-grant received from the Netherlands Organization for Scientific Research (NWO).

Sunday, May 31, 2009

World's Largest Laser

World's largest laser opens for business in California

Another day, another laser... well, not so fast. This particular laser just so happens to officially carry the "world's largest title." Built at Lawrence Livermore National Laboratory in Livermore, California, and housed in the National Ignition Facility -- or NIF -- it was completed at the end of March, and has just now been officially dedicated and opened for business. The laser inside the three-football field-sized building will aim to create a "star" on earth by focusing 192 beams at a pea-sized target, generating temperatures over 100 million degrees and pressure over 100 billion times the earth's atmosphere. The process will create nuclear fusion -- the reaction that powers the sun and the stars. it sounds pretty complicated, and we'd hate to be in town if something goes awry, but we're crossing our fingers for the team! Hit the read link for much, much more information about the project.

LED Lights Positioned to replace CFLs

Some of the things many people have complained about on compact fluorescent light bulbs either aren’t true, or aren’t as true, with today’s bulbs as the first generation of them. They do warm up quicker now, and have more natural light tones.

But, it’s true that you can’t use them in dimmer switches, and they still contain mercury.

That’s why, especially as engineering lowers prices, more large-scale applications and users are going LED instead of CFL. In addition to these benefits, there’s another HUGE one for outdoor lighting, which is a drawback for LEDs in other spots.

Because LED lighting is directional, street lights get their light concentrated where it needs to be — and the night world outside city streets sees a cut in light pollution.

Sunday, April 12, 2009

Will IT LENS ?

Not long ago, a bunch of us in our Santa Monica office pooled together the money to buy a four-foot by three-foot Fresnel lens. We've since been spending our lunch hours out in the sun playing with it.

A normal lens this big would be several feet thick and weigh a proverbial ton (the right-hand image below). However, it's possible to remove much of the inside of a lens and collapse down the shape without introducing too much distortion (the left-hand image):

Fresnel (pronounced "freh-NELL") lenses are used in overhead projectors and lighthouses. We've been using ours, however, to see what happens when you focus 1,000 watts of sunlight onto a single point. It's like when you were a kid and tried to burn ants with a pocket magnifying glass — but 400 times stronger. We built a wooden frame to keep the lens flat and focused, and a stand to hold it steady:

The light in the focal point is so bright that you can't look directly at it without welding goggles.

The lens maker claimed you could melt a penny with it, so that was the first thing we tried:

Modern pennies are made of zinc with a copper coating. The bottom row shows what happens when you put a penny in the focal point of the lens: the inside melts away and the coating stays intact (zinc melts at 693 kelvins, copper melts at 1,356 K). But if you heat it just enough, the metals mix and you make brass (the gold-colored penny in the middle). Older pennies (those minted before 1982) are almost entirely copper, so they didn't melt (top row).

We also had an aluminum can:

The water we poured in boiled quickly, while the can itself became so brittle that we poked holes through it with nothing more than sunlight.

Then we tried cooking. Popcorn did both what you'd expect and not quite what you'd expect: when you really focus the light on it, it kinda pops but mostly burns. However, if you don't put it directly in the focal point, so the light is spread over a larger area and doesn't heat it up as quickly, you can get a whole bunch of kernels to pop without burning too much.

The steam/smoke coming up from the kernels really highlighted the spectra from the lens beautifully. Our yield was very low (lots of unpopped kernels for each popped one), but at least we had real popcorn!

When we tried to cook bacon, about a third ended up well done, a third was burnt, and a third was uncooked. Cooking with the lens is difficult because it heats stuff up too hot too fast. But the well-cooked parts tasted great, so we added an egg:

(We didn't lens the spoon; we used it to eat the egg afterwards.)

It's been fun experimenting with different lensing techniques and items and we've learned a lot (including where the nearest fire extinguisher is!). These are just the highlights — we've lensed gourds, soap, gummy bears, CDs — you name it. Next on our list: marshmallows!

We've got more details and more pictures of our results on Alan's personal blog. If you have ideas of other things we should try lensing, we'd love to hear suggestions.