Sunday, September 10, 2006

Khosla's excellent Articles on Biofuels

Articles and Presentations on Biofuels - by Vinod Khosla founder of Khosla Ventures

A series of papers, powerpoints and videos discussing thoughtful rationale in efforts to partially transition to use of renewable fuels - most notably in the automotive sector. Pragmatism, coupled with can do attitude in acheivable and useful innovation covered indepth. Excellent reading to understand the issues and motivations behind the desire to transition to use of some Biofuels.

Written from the perspective of a world class leading Venture Capital investor, who is taking his own capital to effect a positive partial transition in automobile fueling infrastructure. The strategies and rationale are emumerated in a thoughtful and measured manner, the intent to attempt reducing pollution and environmental burdens of automobile transportation among other matters.

Pictures of Metallurgical Silicon Refining

This is a pictoral description of the typical industrial scale process used for metallurgical polysilicon production by Carbothermic Arc Reduction. Most common application of the output of arc reduction of silica to form polysilicon, is for aluminum and steel metal alloying feedstock.

But with care in the selection of the quartz silica and carbon raw material purity and in details of the furnace operation and materials postprocessing, this process is used for the feedstock for subsequent refining to produce solar grade polysilicon. It is apparent that Arc Reduction of silica, is an an energy hog, as one can observe in the furnace picture below.

Solar grade silicon, although presently capacity constrained, is not subject to exactly the same hard limits as electronics grade poly, especially since the logistics of capacity increases for solar grade are not nearly as arduous nor as capital intensive as electronics grade polysilicon capacity. Although solar grade silicon still requires unusual care in the materials production, it is vastly simpler than electronics grade polysilicon production.

This - carbothermic arc reduction of silica - is how the bulk of solar grade polysilicon used by Qcells - the worlds largest manufacturer of silicon photovoltaics, is produced and similarly solar grade polysilicon for the up and coming Evergreen Solar, a new strategic partner with Qcells .

As a process engineer, one can be curious as to how one might improve energy efficiency of this relatively old method of electrical arc chemical reduction of silica to form polysilicon might be improved upon ??? Evergereen is doing some of this, but are there even better ways??

One the face of it, one can observe that the repeated heating and cooling from the reduction remelting, followed by cooling, then pulverizing, then recasting (heating and cooling) then slicing and then diffusion doping with heat once again to make actual silicon solar cells, is not the best EROI one might envision in an optimized silica to solar cells process.

This is a picture of a massive CarboThermic Arc Reduction Furnace owned by Elkem Silicon of Norway. Input is silica quartz, oxygen and ultrapure carbon and graphite. Apparently there are a number of arc reduction furnaces of comparable size in Elkem's inventory.

The quartz silica feedstock for Elkem silicon's efforts must be unusually pure to permit the use of the relatively crude metallurgical grade arc reduction process to be successfully used for subsequent refining of solar grade silicon. Elkem is a major provider of metallurgical grade silicon to the PV and electronics industries, but it is all further refined by companies like REC, Wacker, and Hemlock before moving on to electronic products.

Q-Cells has purchased its silicon primarily from REC. Evergreen and EverQ also purchase most, if not all, of their silicon from REC (though Evergreen was buying from MEMC until last spring, when MEMC pulled the rug out from under them). Considering that REC holds a 15% stake in EverQ, this is likely to be a durable supply relationship.

The best in the world for ultrapure mined silica feedstock suitable for solar grade polysilicon production seems to be mined at this very beautiful location on the Tysfjord in Norway. The mining operation, with its low cost chemical purification of the raw mineral silica feedstock, is impressive for its attention to detail and the purity of the large deposit of excellent quality quartz pegmatite.

This page shows some interesting pictures of the mine and the manufacturing of the solar grade silica powder. It does not describe methods to purify the powder, which despite the excellent mineralogy of the TysFjord Pegmatite Silica ore, is likely to be chemically treated to optimze the reduction of impurities needed for best in class solar grade polysilicon, at very modest cost increase.

One can envision that this mine provides most of the raw material for Elkem's furnaces, which then ships massive quantities of polysilicon to silicon refiners for solar grade and electronics aspplications.

NOTE updated with input from ALAN on Sept 11 2006

Addendum Dec 9th 2006 - Here are some links to the vistas of the Tysfjord - mountains, maps, and unusual pictures of Orca killer whales inhabiting the fjord itself. Beautiful amazing pictures, not far from the quartz pegmatite mines.

a suspended walkway over a stream

pictures from an Orca whale watching tour ship

amateur photos from a snorkeling tour of the fjord

more of these tour pics with incredible closeups of Orcas in the Tysfjord

maps and more local pictures of a fishing village in summer and winter

Friday, September 01, 2006

FarField Scientific's novel Differential Interferometric Bio / Chemical Affinity Instrument

Farfield Scientific is a small innovative firm, that has taken what would be more commonly implemented in an exotic Mach Zehnder fiber coupled interferometer and changed this into Dual [slab waveguide] Path Interferometer, rendering the experimental sensing configuration easier to use, broadly adaptable and seemingly vastly more sensitive in practice.

Farfield Scientific is a spinoff of the University of Durham's Department of Physics of work orginally done by Prof. Graham Cross.

Farfield Scientific makes a surface sensitive instrument that is readily applied to otherwise difficult to quantify Chemical Affinity testing - configured with a convenient and sensitive optical path for quantifying surface reaction and chemical binding properties.

Where typically it is almost conventional to use a single mode optical fiber coupled Mach Zehnder interferometer for this kind of affinity / binding measurments (or AFM force curves, or exotic surface force apparatus), the logistics of conventional MZ sensing are needlessly bothersome and the information from MZ sensing actually limited in dynamic range and data interpretation due to a single intensity output for the optical path interference sensor. MZ single mode waveguides suffer from limited sample size, and more tedious sample preparation, as is the case of data taking with the AFM and surface force apparatus. This among several limits to other chemical affinity measurement methods.

Farfield's scientists Prof. Graham Cross of Durham University and the company team have implemented a novel and simplifying optical configuration to enable practical application of large dynamic range interferometry methods to chemical reaction / binding quantification- with interferometry's inherent amazing sensitivity, but in a very practical optical path with the benefit of imaging projected farfield interference patterns rather than a single intensity signal from an otherwise typical MZ interferometer.

This last seemingly trivial point, of measuring from projected interference patterns is actually critical to more widespread application of interferometric sensing of chemical affinity, and is where otherwise conventional Mach Zehnder configurations are prone to errors in signal generation / interpretation - or at least suffer from limited dynamic range.

Here is a list of links to titles of some of the firm's earlier applications notes

Polymer Surface Interaction
Quantitation of Surface nanostructures by DPI
Real Time observation of Actin Polymerization
Early Stage B-Amyloid Aggregation by DPI
Calcium Ion Binding effects on Transglutamase
Real Time Lipid Bilayer observation
Physisorbtion and effects of Surfactant
Real Time Studies of Protein Lipid Interactions
Contact Lens Biocompatibility
Structural Change in Antitrypsin on Small Molecule Binding
Changes in MAP Kinase for Small Molecule Binding
Biotin Streptavidin interactions
Molecular basis for an Inhibitor of B-Amyloid Aggregation

Beta Amyloid Aggregation under Different Surface Conditions
High Resolution Real Time studies of C12E4 Surfactant
Small Molecule Partitioning into C18 membrane Mimics
Affinity Studies of Glycoprotien Lectin interactions
Synnuclein Agreggation
Effect of Melittin on Phosphatidylcholine Liposome Interactions
Properties and Aging Behaviour on Thin Spun PVC

It is clear that the firm is tending towards biochemical applications of the technique and this is good and attests to the power of the basic method as to the ease of experimental data capture and sample preparation, and the sensitivity of the measurement.

The basic optical path technique has been previously applied to novel sensor heads for pressure and humidity sensing among other applications, but the real home for the astounding innovation is in studying biochemistry.

Here is a link to patents [US, US apps, and EU] that are mostly from Prof. Graham Cross (plus a few unrelated stragglers of no connection). Most in the list are relevant to the sensor technology with a few fairly obvious exceptions..

I will profess to hardly hearing of this method until I observed folks from the firm visiting my blog. I was hugely intrigued by what I learned at the Durham and Farfield web sites. The business strategy of focusing the application of the innovation on scientific markets with a full up instrument and support with a nice array of application notes reminds me of the early days of growth of Digital Instruments, albeit the market has slightly less dynamism / imperative than the heady early days of AFM.

Congratulations to Prof. Grahama Cross and the Farfield Scientific team are deserved for the superb and novel innovation commercialized. The instrument is conceptually simple, the device technology is superbly elegant and enormously powerful.

I'd love to see some biochemical / medical challenge elucidated quickly by Farfield's Dual Path Interferometer, aside from seeing the firm grow to the sucess that it seemingly deserves. More chemists, biologists and their relatives should learn about the power of Farfield's instrument technology.

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