GCEP Research Symposium 2008

The Global Climate and Energy Project (GCEP) held its fourth annual energy research symposium at the beginning of October 2008. As GCEP recently reached its five-year milestone, the theme of the conference will be “Energy Research-  Five Years and Beyond.” Researchers from Stanford and around the world will discuss the project’s progress as well as the opportunities that could lead to energy technologies with significantly reduced greenhouse gas (GHG) emissions.

The three-day event is free and open to the Stanford community and other researchers and energy professionals.

The symposium will open with a keynote address given by Mary Nichols, Chair of the California Air Resources Board.  The first day of the conference will include general sessions in which representatives from a number of university-based energy research programs will give their outlook on energy research in the next five years. Technical leaders from GCEP will also give an overview of the research progress made and the opportunities that lie ahead in a broad set of energy areas over the next five years.

The symposium will cover the following topics:

Wednesday, October 1 (General Session)

• Morning: Perspectives on Energy Research in the Next Five Years 
• Afternoon: Progress in Energy Research and Opportunities in the Next Five Years

Thursday, October 2 (Technical/Poster Sessions)

• Morning: Solar Energy
• Afternoon: Biofuels and Bioenergy Conversion

Friday, October 3 (Technical/Poster Sessions)

• Morning: Carbon Capture and Storage
• Afternoon: Advanced Energy Transformations and Storage

GCEP Overview

• Been in existence for 5 years
• Researches low-GHG emission energy conversions’
• Interested in high-risk/high-reward projects
• Funding: $225 mill over 10 years
• Sponsored by Exxon, GE, Schlumberger and Toyota
• Solar is biggest area of research, also hydrogen, electrochemistry (battery and fuel cells), carbon capture and storage
• 70 principal investigators, 300 graduate and post-doc fellows

Planning for Innovation: AB 32 and the Role of Technology

Mary Nichols, Chair California Air Resource Board (CARB)

• AB 32 is two years old and mandates by 2020 gets 1990 levels, roughly a 30% reduction and by 2050 a 80% reduction
• People want to do something about global warming including sustainable energy and zero emissions vehicles, however there is a lot of political resistance with the divisions of agencies and budgets in congress
• People see climate change as an environmental issue separate from energy policy
• Audience member, heard at MIT conference: CO2 capture will cost consumer $100 per month, $100 per ton of CO2 for carbon capture and sequestration
• Against Prop 7 because it will cause too many restrictions

ZEV (My questions)

• Question: There has been a lot of turmoil over the Zero Emissions Vehicle (ZEV) program, can you talk about the current status of the program and where it is going?
• ZEV was deigned to be just an air issue, not a CO2 issue
• Lots of good research came out of ZEV program, but manufacturers never invested enough money to manufacture ZEV cars
• Car companies getting squeezed, not making money on US sales, but still making money on Europe sales.
• Redoing standards so there is one standard for both emissions and greenhouse gases.
• Cars are now 99% cleaner than when they started, so it is hard to justify a ZEV program based just on emissions, but it is important for CO2
• Trying to be practical about getting the most technologically advanced cars on the road, not “getting into bed” with the manufacturers
• Current ZEV program now is way to complicated, not even car companies can understand it
• Tweaking it so manufacturers can get more credit for hybrid vehicles, not just for ZEVs
• Seeing massive interested in plug-in vehicles by 2011 and 2012, which will be good at getting people used to plugging in

The Challenge of Low-Carbon Transportation Futures

Joan Ogden: Transportation Studies, UC Davis

• Direct combustion of fuels for transportation and heating accounts for 2/3 of primary energy use
• World transportation is 97% dependent on oil
• Number of vehicles worldwide expected to triple by 2050
• Three approaches: Efficiency, alternative fuels, reduce miles
• Doubling vehicle efficiency world wide could become one “wedge”, or using zero-carbon fuels
• Could improve fuel economy by a factor of two by doing things we know how to do now, like CVT and turbo-charging
• NRDC study estimated smart growth community would create 62 percent less GHG
• Vehicle Commercialization Takes Time (NHA Martch 2008: Cunningham, Gronich and Nicholas): R&D can be decades, prototype and demonstration can take 5 years. Pre-commerical sales several years, early commercialization more than 5 years. Total cycle can take 25 years before new vehicle is ready for mass market. Lesson: lots of stuff that needs to happen at low volumen before
• Automatic transmission had 60% growth at first, then was 15% growth
• We don’t need as many gas stations. If only 5% of gas stations offerred new fuel, it would be enough because drivers would only be a few minutes away
• Major transportation infrastructures take 30 to 70 years to build out
• Adoption: historically 20 to 60 years from R&D to greater than 35% of fleet
• BEVs promising. Questions: how much battery is consumer willing to pay for? What will the cost be – will they make it into large scale acceptance?
• Will H20 vapor from H2 fuels have any impact? Some people have looked at this and concluded that it probably is not a problem and is about the same as ICE

UCDavis STEPS program (Sustainable Transportation Energy Pathways)

• Goal is to develop tools and methods for alternative fuel and vehicle paths
• Comparative analysis research, Knowledge dissemination, Education
• Prelim results: H2 produce biggest reduction in gas, making ICE cars more efficient 2nd and biofuels least helpful. BEVs would be similar trend to H2.
• Portfolio approach much better not viable to rely on single solution
• Interesting areas of research: Regional fuel supply systems and interaction with electric sector

Cellulosic Biofuels

Chris Somerville: Energy Bioscience Institute UC Berkeley

• Biofuels theoretical should be carbon neutral but tilling, land conversion, fertilizer, transportation and processing can all create CO2
• His research shows that corn ethanol just barely positive for CO2 emissions, but cellulosic ethanol very CO2 advantageous
• 140 billion gallons of gas used in US each year
• Production of biodiesel from virgin vegetable bad idea. Produces of biofuels 63 gallons from acre of soybeans, cellulosic can get up to 2000 gallons
• US biomass inventory is 1.3 billion tons. COrn stover can produce 26 B gals (20% of biomass), perennial crops could produce 46B gallons
• Could use acres that we pay farmers not to plant, also could use land no longer farmed
• Challenge of cellulosic fuels is that capital costs are substantial but unknown. Probably $5 per gallon.
• 22 groups building modest, pre-commercial plants
• Limiting factor is getting consistent supply of bio-mass
• For agriculture and forest residues that produces 2 tons/acre a 5,000 ton/day biorefinery would require a radius of 50 miles to support it. However a 20 ton dedicated enrgy crop would shrink that area by 90%
• Miscanthus growing in Illiinois with no water or fertilizer produced 26.5 tons at maximum, normally 20 tons
• Miscanthus in same family as sugar cane but much more tolerant of cold. Can survive underneath snow.
• Switchgrass not as good as miscanthus
• Plants like Miscanthus have a perennial root so harvesting more efficient and stores carbon underground
• Miscanthus seems to have a nitrogen fixing element because one test showed that adding nitrogen fertilizer doesn’t increase growth
• Perennials have little or no erosion, unlike corn or soybeans. This also means that they can be grown on sloping land
• Perennials have many benefits for biofuel stock
• One ethanol process is claiming 100 gallons of ethanol per ton of biomass
• One challenge is that biomass is not dense so better to have local processing, less than 30 miles
• 50 grams of enzyme needed per gallon of ethanol which adds about $1 per gallon
• Enzymes don’t penetrate biomass particles but work on the surface which is slow
• Improved catalyst exploration: termite enzymes, look at compost heaps and forest floor, in vitor protein engineering, develop synthetic organic catalysts (that penetrate biomass)
• Also looking at ionic liquids to pre-treat biomass to make it more susceptible to hydrolosis
• Current fermentation only utilizes glucose, but if other sugars are fermented prices can be decreased by a dollar or more
• However, ethanol can only provide about 10% of the energy for current fleet, so it would be better to make diesel rather than ethanol
• Some companies claim to make diesel for $60/bbl
• It is possible to convert sugar to alkanes using H2 (which is the principal component of diesel), but research in this area is just starting. In this case, the alkanes becomes a carrier for H2
• Normally conversion processes loses half of the carbon, where above doesn’t
• Algae is about $4 per pound, but woodchips about $0.25

Solar Energy

Martin Green, UNSW

• PV bottleneck expected to disappear over the next 5 years
• Thin-film still a small part of market
• PV normally competes at retail price of electricity, not the wholesale price
• German study predicts 64% of energy use by 2100 will be PV
• By 2012, estimates that PV will have 50 GW of new capacity, more than wind
• Last year wind supplied 1% of world energy, PV had about 10 GW of installed capacity but may reach 1% by 2012
• China has a lot of thermal solar water heating
• Recent PV efficiencies for concentrating systems are much better than Stirling engines and more reliable
• German feed-in tariffs didn’t cost customers very much more, some of which was due to reduction in cost of generation
• PV now uses more silicon than microelectronics, and total value of PV will soon exceed microelectronics too.
• Thin film has some problems: CdTe is problematic because cadmium is very toxic and tellerium is rare
• Organics may have problems with efficiency and durability
• $2.20 per watt is current manufacturing cost of first generation PV
• First Solar reports manufacturing costs of just over $1 per watt

Bioenergy and Bio Conversion: A Great Green Hope or Impending Disaster?

Chris Field, Stanford

• Hope: net fossil fuel offset
  • Senate energy bill calss for a 7-fold increase in ethanol production, 36 billion gallons/year by 2022
• Threat: impacts on food, water, net warming, water pollution, conservation areas, biodiversity, rural jobs
• Biomass is still a substantial part of he global energy system
• Energy usage has been growing about 3% per year lately
• If we took the global crop production and converted it to energy at 100% efficiency (and didn’t eat any food) it would provide only 25% of the worlds energy need
• Grazing land with food animals is an efficient way of converting low yield land areas into a high value product (meat)
• Abandoned land reasons: wrecked, technology change enabled use of better land elsewhere (shipping), increased yields means it is no longer needed
• Abonded land is about 1 billion acres
• Better to shift biomass directly into electricity generation rather than fuel system. Electricity generation is efficient and coal-fired plants can already accept a mix of biomass.
• Coal is $10 to $150/ton, oil is $700 ton, corn is $250 ton.
• Latest studies show that corn ethanol has an EROI of 1.2 to 1.4
• It is important that we take advantage of every energy source we can, but we need to be smart about it, especially if we are concerned about CO2 impact

Advanced Energy Transformation and Storage

Chris Chidsey, Stanford

• GCEP portfolio under represents pumped hydro, pre-compressed air, flow batteries
• Batteries: heavy, expense, slow
• Fuel cells: expensive, inefficient, hot, unselective
• Other areas electricity is being used:
  • Electrolyzers: expensive, inefficient
  • Electrosynthesis: aluminum, chlorine and sodium hydroxide
  • Electropurification: electrodialysis, salt splitting to acids and bases
• How to avoid electric storage?
  • Renewable peaker plants: small-scale hydro, biomass, geothermal
  • Opportunistic energy use: refrigeration, heat pumping, electrosynthesis

Three Perspectives

• Interconversion of chemical and electrical: fuel cells, batteries, greener chemistry (chemical processing)
• Control catalysis at the atomistic level: heterogenize homogenous metal catlysts, tail each atom of the catlyst molecule
• Chemical transformations: O=O reduction, C-H oxidation

Fuel Cells

• Polumer-Electrolyte-Membrane (PEM) fuel cell
• Dioxygen reduction is very inefficient
• Hyrdogren is an inconvenient fuel
• Methanol is better
• Liquid hydrocarbons would be an even better fuel

Batteries

• Lithium-ion batteries ready
• Vanadium flow batteries not ready yet
• Goal energy-dense liquid products from inexpensive reactants
• Reverse fuel cell, like propylene and water to propylene glycol

Carbon Capture and Storage – Power Cycles, Field Projects & Site Selection

T.S Ramakrishnan, Schlumberger-Doll Research

• 35 storage fields need to be built each year until 2025
• Post combustion flue gas: 70% N, 10-15% CO2
• Post combustion hard to capture CO2 because of the volume of gas, pre-combustion is easier
• CO2 dehydration and compression needs to remove contaminants and this increases the cost
• Excluding transport, storage and containment costs $30 ton CO2 for oxy-fuel, pre-combustion more, post combustion almost $40.
• In Germany, Vattenfall 30MW oxy-fuel plant is being built
• In US, Decatur test site being developed at the corn ethanol plant
• Monitoring CO2 injection
  • Seismic is not very sensitive past 10,000 feet
  • Pulse neutron capture: very narrow field
  • Others: well-to-well acoustics, sampling (surface based Utube,, downhole
• Costs $1/ton to move CO2 100 km
• In US, most coal plants have suitable sequester site close by
• There are problems if sequester site is close to a power plant because seismic methods don’t work well because of 60hz interference
• CO2 pumped into water doesn’t displace all water, but instead displaces 5% to 10%
• 5.3 M tons, which is about 1 y for a 1GW plant needs site 2000 meter, height of 30 m
• Don’t want a site of high permeability because it will migrate more. But this is opposite of what is desirable in an oil field
• For CO2 EOR (enhanced oil recovery) want homogenous formation, but it is opposite for CO2 sequestration
• Also desired to have higher permeability at the bottom of the site
• Deeper is safer and densier but more expensive due to higher compression costs.
• 1500 to 3000 meters is ideal
• CO2 can combine with different minerals which can cause problems
• Legally restricted to stay below the fracture pressure
• Major problem is dip. 1 deg is manageable, but 5 degree causes a 15 to 20 km migration over time
• Anticline the best structure
• Water salinity problems: CO2 migrates up and doesn’t dissolve as well

New Directions for GCEP Research

Sally Benson, Stanford

• Portfolio developed by annual solicitation from Stanford faculty
• Also targeted world-wide solicitations:
  • New batteries for transportation
  • High efficiency solar PV
  • Lignin management in biofuels

Review of Advanced Electricity Workshop

• Grid is the legacy of a century of incremental development
• Stability and reliability are significant concerns
• Integrating intermittent renewable and distributed resources posses challenges
• Current system is built around centralized and large generation
• Local disturbances can have wide area impacts
• Lack of information about the distribution on the grid
• Enhancements for integration of renewable energy
  • Storage
  • Multi-layer communication and control
  • Bi-directional power flow
  • Local information and awareness
• Found "smart-grid" was really about demand management
• Issued RFP in May of 2008 and funding decision expected Dec 2008

Third Generation Photovoltaics

Gavin Conibeer, UNSW

• Third generation will be from 20% to 65% efficient and from $0.20 to $0.50 per watt
• Main losses in PV:
  • Sub bandgap losses
  • Lattice thermalisation
  • The above two count fo 50% of the losses
  • Also Junction loss, contact loss, recombination
• Efficiency: Single p-n 31%, multiple threshold 68.2%
• Tandem cell: put together multiple cells and direct energy to the appropriate one
• Si QD (Silicon Quantum Dots) can be fine tuned for different energies

Hot Carrier solar cell

• Narrow bandgap material absorbing a wide range of energy but extract energy before they thermalise
• Need to slow carrier cooling
• Collect carriers over anarrow range of energies
• Renormalisation of electon hole energies
• Electrons carry energy give off optical phonons
• Created bottleneck affect which slows further cooling
• Phonic band gaps - modulate acoustic impedance
• Looking at colloidal dispersion of nanoparticles

Materials for High-Efficiency, Low-Cost Thin Film Solar Cells

Alberto Salleo, Stanford

• What really matters is $/watt: goal is $0.30 per watt
• Last year 40% efficiency was achieved, but was very expensive
• Multi-layer cell made with low-cost printing, coating and lamination technologies at rates like 100 feet per second
• Make all components, metals, semiconductors and oxides in liquid form
• Two junction parallel-connected cell where the power is pulled from the side
• Leads to an efficiency of 12.3%
• Conductive layer looking a Ag (silver) nanowires and ZnO
• Ag nanowires conduct almost as well as theoretical mesh but is much cheaper than ITO
• ZnO is deposited using vacuum techniques, has to be above 300 deg C and is difficult to control
• However ZnO can be synthesized in solution because it likes to form wires
• ZnO formation helped by oleic acid and Al or Ga doped
• Once nanowires are created in solution, can deposit by drop casting, spin-coating, or spray coating
• Still getting only 1k ohm per sheet, so they need to reduce this by an order of magnitude

Lateral Nanoconcentrator Nanowire Multijunction Photovoltaic Cells

Peter Peumans, Stanford

• Problems of multijunction cells
  • Current through each subcell must be matched. This is hard and only works for 1 spectrum
  • Cells must be grown in a specific sequence on top of each other
  • Growth process (epitaxy) is expensive and slow, several hours per batch
• Idea: nanowire based, spectral splitting using metal antennas/filters in the optical domain, independent contacts to different cells
• Problem: hard to make sure that most of the photons are absorbed by the nanowire
• Ag fractal structures concentrate specific energies in one spot
• Photon absorbing nanowires can be analysed as electric filters using capacitors and inductors
• Ag bowtie antenna gives spectral selection and optical concentration
• Right now 50% of the energy going into semiconductor not wire so this is an area that needs to be improved
• Techniques to fabricate nanowires: Ag meditated etching, vapor-liquid-solid, templated sol-gel plating
• Ag etching works but has problem with wires clumping which may be solved with critical drying techniques
• VLS after growth is a darker chip because more light is absorbed
• TiO2 dye-sensitized grown by etching holes in organic polymer
• Building testbed to test individual Si nanowires

Artificial Photosynthesis: Membrane Support Assemblies That Use Sunlight to Split Water

Nate Lewis, Caltech

• Goal use sunlight to produce fuels directly
  • Going to electricity only is good for peak shaving
  • Plants have figure out how to convert sunlight to fuels but are only 1% efficient. Saturate at 1/10 of a sun to prevent damage
  • Doesn't matter what fuel is produced since it is possible to convert to other fuels
  • Work on producing H2 first
• Already have materials that produce H2 from sunlight at 5% efficiency
• Most material will degrade, they are looking for others that work better
• Nature separates reduction process from oxidation process, so they are looking at membrane to do this
• Normal silicon cells have problem because they have to be thick to absorb photons but thin and pure enough so the electrons can make it to conductor.
• Nanostructures avoid this since photons can be absorbed only length of wire but electrons only need to migrate out radially
• Numerous examples of this are in nature: forests, roots, etc
• They are only considering elements that are relatively inexpensive
• Nanowire structure can support these elements that aren't as active
• Use porous aluminum mask to grow CdSeTe nanorods
• Test show that these nanorods shows better results for red light than similar planar geometry
• Can grow cheaply very regular 4nm Si rods that can reach 10% to 12% efficiency
• Imbedding Si rods in Polymer (PDMS) resulting in a flexible, organic material. Can then shrink the polymer so the rods stick out. Can also contract spacing. This can be rolled and unrolled.
• Can also reuse template after peeling. Probably can go 100 to 1000 layers off of one substrate, further reducing their cost.
• Also working on O2 catalyst using Fe2O3 nanowires
• Eventually could put these together to split water into H2 and O2 

Direct Solar BioHydrogen

Jim Swartz, Stanford

• Using cell-free protein synthesis of H2
• H2 can be used for power plants, fertilizer and cement and be located near the production source of H2
• Assuming solar incidence of 7kWh/m2-day in South West, 15% efficiency need about 17,000 sq miles which is 2.5% of current cropland
• Direct bioconversion needs large surface area with organism suspended in fluid that is constantly mixed. Capture with low pressure through membrane of purge gas.
• Estimated economics allow about $20-$20 per sq ft
• Need: O2 tolerant hydrogenase, express and activate foreign, H2ase, remodel antennae, control electron and proton flux rates
• Using directed evolution to evolve oxygen tolerant hydrogenases
• Many advantages of using cell-free protein synthesis, one of which is the ability to evaluate millions of mutations
• Found a mutation that has higher activity, but not O2 tolerance
• Revised plan: introduce rational mutations, DNA shuffling to combine beneficial mutations, develop ultra-high throughput screen
• Conclusion: Solar BioHydrogen appears to be technically and economically feasible

 

Generating Novel Yeast Strains for Improved Biomass Conversion

Gavin Sherlock, Stanford

• Fermentation problems: Need cooling to keep at 30-35%, ethanol is toxic to yeast, problems making hybrid yeasts
• Their approach: start with a pool of many diverse clones, select over 100s of generations, recombine those traits
• Grew over several hundred days with increasing temperature to select those that were tolerant of high temperature
• Was able to find strains that survived up to 46 deg and 15% ethanol
• Tested for Xylose tolerant and found 31 positive strains
• Looked at the "Simi white" strain and verified that it using Xylose is recognized as a carbon source (but maybe not actually metabolized)
• Tried deleting certain genes and reductives to see what affect it has
• Future: finish deletion analysis, clone and identify Xylose positive trait, analyze other traits, evolve better strains

Biomass Energy: The Climate-Protective Domain - Analytical Models and Techniques

Scott Loarie, Carnegie Institute of Washington

• Result neutral: goal is to crunch numbers to see biomass use affects
• In Brazil, deforesting is happening from the south-east - moving into the central
• Expecting carbon emissions to increase 25% by encroached areas
• Its not all carbon, surface albedo also causes changes in climate
• Deforestation causes albedo change
• Albedo change is complex, can be affected by: reservoirs, sylvaculture (reforesting with different species), grazing, drought, finger lakes
• Goal: discriminate biomass energy, track expansion, model the impact on climate

Designing Lignins for Improved Biomass Processing

John Ralph, Univ of Wisconsin

• Pulping mill costs $1b to build
• Lignin formed via a combinatorial radical coupling reaction
• Lignin contains many different linkages and can contain billions of isomers
• Lignin is responsible for much of the recalcitrance of biomass fermentation
• Can take out lignin but it is very energy demanding
• Can disregard lignins by burning, but if sugar is desired need to deal with it
• Plants need lignin for structure and water transportation
• Can genetically reduce lignin content in plants but not much results in this area
• Lignin incredible metabolically plastic: can change them with no outward affects
• Improvement: add zips so lignin breaks down easily and is more water soluable
• This improves processing efficiency (of grasses) from 70% to almost 100% at 160 deg, or 90% at 100 deg or 70% at co deg C
• Some plants like balsa, already makes conjugates like this
• Questions left: can they find the gene for this and insert it into a plant?

Development of Innovative Gas Separation Membranes Through Sub-Nanoscale Materials Control

Yuichi Fujioka, RITE

• RITE: Research Institute of Innovation Technology for the Earth
• CCS chemical absorption consumes 80% of the energy in a CCS system
• Target for Co2 capture using precombustion membrane: Less than 1GJ per ton CO2, less than $20 ton-Co2
• Carbon membrane has decreasing performance in humid conditions
• Carbon also needs 10x as much area
• However, adding CO2 affinity material, especially Cs2CO3, increases performance under humid conditions
• Working on PAMAM membrane but it must be kept dry to work well

Multiphase Flow for Carbon Dioxide and Brine

Sally Benson, Stanford

• 60% of fossil fuel emissions come from large stationary sources
• 40.5% from coal, mostly for power generation
• Store CO2 in: depleted oil and gas reservoirs, for enhanced oil and gas recovery, deep saline formations, use in enhanced coal bed methane recovery 
• Saline aquifers in sedimentary basins are widely distributed and co-located with CO2 producing plants
• Saline aquifers have larger storage capacity, lower about 1000-10,000 GtCo2, versions 675-900 for oil and gas fields (IPCC 2005).
• In US 920 to 3,380 GtCO2 capacity in saline aquifers
• It is complex to study how CO2 will react. Not much information about relative permeability and capillary pressure curves
• Her team called "Sequestration Lab"
• In lab experimenting on real rock samples 5 cm by 15 cm
• If rock is very homogenous, then CO2 will tend to float to the top due to gravity
• In heterogenous rock, rock is saturated after inputting about 2x pore volume of CO2
• Still many questions to be answered and need to develop theoretical model

 

Supercritical Water Coal Conversion with Aquifer-Based Sequestration of CO2

Reggie Mitchell, Stanford 

• Coal is the cheapest and most abundance of all fossil fules and will continue to be used in the future
• From 2005 to 2030 electricity generation will double and coal use will also double
• There is 37% more Co2 in the atmosphere than in 1900
• 21.3% of all greenhouse gas from power stations, in a large part from coal
• 11.3% is fossil fuel retrieval, processing and distribution (getting coal to the power plan)
• Supercritical water (SCW) is at 218 atmospheres and 650 deg K
• There is enough saline storage capacity to store 86 to 318 years of coal CO2
• Coal gasifications products will be dissolved and all salts can be removed from the ash
• Process rake brine and remove salt, feed to gasifier which produces syngas for combustion then at high pressure will mix back in the salt and re-inject
• Lots of material issues with SCW from high temperature, pressures and corrosion from salt-water
• Gasification is endothermic so heat needs to be added to keep up the temperature. They add O2 to autothermal operation to burn some of the coal to produce the heat
• Systems analysis: need to preheat and pressurize water, separate O2 from air which take energy, but can achieve 42% efficiency
• Salt precipitates out of SCW so no extra energy is needed to desalinate the water
• Typical IGCC systems produce 770 kJ/kg Coal where the SCV system produces 1230 kJ/kg coal.
• Zn, Cu, Cr, As will precipitate out of solution
• Conclusion: Maximum efficiency while capturing CO2, non-zero traditional air emissions, size reduction of reactor vessel
• 500 MW plant sill be 200-300 kg per second, only 1/10 of this water goes through the reactor, but it all goes back into the ground. The amount of water needed is the same as a traditional coal power plant down to 1/10 the amount
• Could go to demonstration stage in 4 to 5 years 

Anatomy of a Coal Bed Fire

Lynn Orr, Stanford 

• Coal beds are a source of CO2 from coal bed fires, 
• China burns 200 million tons of coal from coal bed fires
• Once coal bed fires are started they are hard to extinguish
• In deep coals they pull the water out to produce methane
• Looking at fire in San Juan Basin by Durango, CO.
• Coal seam breaks out to surface
• Fissures from and produce Co2, CO, CH4, H2S, N2 and a little O2. Precipitates S2 and ammonium chloride
• This is O2 limited combustion
• At 50 ft, it can reach 1000 deg F, effluent gases are 1500 deg F
• There is subsidence after the coal burns
• After edge ignited combustion starts and the subsidence induces stresses that open existing fractures and resulting fissures (chimneys) create buoyancy-driven flow that sustains the fire
• This is why they are hard to put it out - they create lots of cracks
• Looking at injecting Co2 to disrupt the O2 flow
• No method of extinguishing a coal-bed fire have been demonstrated (although many methods have been tried)

 

Development of Low-Exergy-Loss, High-Efficiency Chemical Engines

Chris Edwards, Stanford

• First CGEP project: think through on a fundamental basis how to make really big gains in engines by stepping back and looking at exergy
• Lead to "extreme states principal" - do combustion at the highest heat and pressure possible
• Higher compression advantages: less exergy in exhaust and combustion
• Otto cycle should get about 45% efficiency at 10:1 compression, and 70% at 100:1 compression. He is targeting 70-80% of the in real-life machines
• Leads to: 15,000 PSI, 3300 K
• In current engines, things are done slowly, for instance race car is limited to 22,000 RPM because of connecting rod limitations, not combustion limitations
• To reduce heat transfer: Large top dead center (TDC) volume, high piston speeds
• For high speed need free pistons.
• Free pistons not new, used in past for air compression or electricity generation
• Critical questions: high engine and temperature, rings (less than 1% blowby), control combustion
• Found light piston moved too fast and produced acoustical waves so moved to a heavier, slower piston
• Losses consist of heat and mass (air blowby) and are about 10% to 20% total,
• 8% is mass losses but should be able to get this down to about 2% maybe using dynamic rings
• Currently using 1kg piston, mean speed 40 m/w peak speed 75 m/s
• They are now seeing same efficiency as diesel, about 40% but can do much better once they get air loss down
• This design can use many different types of fuels, but it will have to be designed to accommodate that fuel

Nanoengineering of Hybrid Carbon Nanotube-Metal Nanocluster Composite Materials for Hydrogen Storage

Anders Nilsson, Stanford  

• First project was storing H2 in carbon nanotubes
• Lots of energy required to convert molecular hydrogen to H2 and back
• New project is looking at keeping H molecular in storage and fuel cell
• Idea: store H in the chemisorbed form on a carbon nanotube surface
• Investigation: hydrogenation in place 
• Getting 7% by weight storage capacity
• Optimum carbon nanotube radius is 1nm
• Doping nanutubes with Pd or Pt increases its H uptake
• Vision is to store H as it is produced by running fuel-cell in reverse, so fuel-cell could be like a battery
• Pt covered SWCN allows storage of H+
• Audience: No good material storage right now for H2, all approaches have problems

 

Nanoscale Architectural Engineering for High-Performance Solid Oxide Fuel Cells

Sossina Haile, Caltech 

• Fuel cells most efficient, clean way to convert from chemical to electrical energy
• Solid oxide fuels cells (SOFC) offer fuel flexibility
• Barrier today is cost per power (especially at lower temperatures)
• Their objective is to dramatically improve performance to increase cost/power
• Current SOFC achieve greater than 1 watt/cm at 600 deg C.
• Goal: increase power output by 10x by changing architecture
• Hypothesis: fuel electro-oxidation occurs on ceria surface, anode is rate limiting, cathode is surface area limited, electrolyte is grain boundary limited
• "Triple points" of meeting metal, ceria and H2 not required.
• Better design is a metal nanowire coated with ceria. This means electrons have a short distance to move and surface area is maximized for catalyst. Also can go to cheap metals, oxide coating stabilizes structure and is non-coking (no C growth)
• Cathode impedance is lower by magnitudes than other technologies
• Cathode resistance is almost nothing compared to anode resistance
• Easy to grow CuO nanowires and then reduce in H2 plasma to create Cu nanowires. This increase surface area by 140% but it is too dense so there is no gas phase access.
• Now using polystyrene beads which gives good control over size and spacing
• Coats Cu nanowires with SDC by chemical vapor deposition (working on this now)

 

A Quantum Leap Forward for Li-Ion Battery Cathodes

Josh Thomas, Uppsala University Sweden

•  "The last totally ICE vehicle will be produced about 2034" (unattributed)
• Anode and electrolyte can scale up, but the cathode is holding it back
• LiFePO4 is used by A123
• Li2FeSiO4 is their focus. The Li2 part can double the capacity with some tricks
• Cathode materials: Layered (LiCoO2), Spinels (LiMn2O4), Olivines (LiFePo4), Orthosilicates (Li2FeSiO4)
• Fe based have poor electrical conductivity
• Li2FeSiO4 advantages: potentially lower cost, abundant, non-toxic
• Can give cell voltage of 4.5 volts and 255 mAh/g
• To compensate for low conductivity uses nano-painting with an electronic conductor which also improves particle contact
• Lifetime is unknown
• Even if they get up to 4 volts, don't have electrolyte salts that are stable at that voltage