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Energy Grand Challenges: The role of the Energy Institute, The University of Texas at Austin. IBM Distinguished Speaker Series April 9, 2010 Raymond L. Orbach Director, The Energy Institute The University of Texas at Austin. Energy Security: Deal Killers.

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Energy grand challenges the role of the energy institute the university of texas at austin l.jpg

Energy Grand Challenges:The role of the Energy Institute,The University of Texas at Austin

IBM Distinguished Speaker Series

April 9, 2010

Raymond L. Orbach

Director, The Energy Institute

The University of Texas at Austin


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Energy Security: Deal Killers

  • #1: Global Warming and CO2 emissions from fossil fuel combustion

  • #2: Intermittent energy sources (wind, solar) and the presence and stability of the grid

  • #3: Penetration of plant defenses to produce transportation fuels from biomass

  • #4: Mimicking nature: artificial photosynthesis for solar energy to fuels

  • #5: Spent fuel from nuclear power reactors


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Energy Security: Game Changers

  • #1: Carbon capture and storage through enhanced oil recovery and saline aquifers

  • #2: Electrical energy storage, through batteries and super-capacitors

  • #3: Genetics modification of plant cell wall, and catalytic methods for plant sugars to fuels

  • #4: Separation of solar induced electrons from holes, and catalysis to produce hydrogen

  • #5: Closing the nuclear fuel cycle


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Deal Killer #1: CO2

United Nations Intergovernmental Panel on Climate Change, IPCC-AR4:

  • “Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice and rising global average sea level.”

  • “The human influence on climate very likely dominates over all other causes of change in global average surface temperature during the past half century.”

    [Using expert judgment: very likely > 90%]

4


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Game Changer #1: Carbon Capture and Storage (CCS)

  • Four basic components:

    • Capture of CO2 from power plants, industries, or ambient atmosphere

    • Compression of CO2 to a supercritical liquid phase

    • Transportation of CO2 in pipelines

    • Sequestration of CO2 in geological formations (oil or gas fields, saline aquifers)

  • Risks and barriers of greatest concern:

    • High energy demand of carbon capture and CO2 compression processes.

    • Technical and economic challenges of scaling up CCS systems.

    • Uncertainties in leakage rates from carbon sequestration reservoirs

    • Engineering and geologic limits on injection rates at CO2 into sequestration reservoirs

    • Constraints on the ability of electric utilities to adjust to evolving technical demands and business pressures.

    • Human and economic barriers to the transfer and diffusion of CCS technologies globally.

    • Legal and regulatory uncertainties associated with pending climate change legislation.

    • Public acceptance of the risks associated with geologic sequestration of CO2 and increases in energy costs

6


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Problem: The pulverized coal-fired power plants in the U.S. today produce ~ 1.9 Gt of CO2each year.

Problem: Capturing and pressurizing CO2 from flue gas costs ~ 30% of coal-fired power plant’s energy. Pure cost.

Thermodynamic limit for amine capture is ~ 12%. By using higher temperature liquids, may reduce cost to ~ 20%.

Offset cost by use of captured and pressurized CO2:

Enhanced oil recovery

Enhanced coal bed methane

Production of methane from geothermal aquifers saturated with methane

When CO2 dissolves in brine (10 × more soluble than methane), phase separation produces nearly pure methane, analogous to competitive adsorption.


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Assumptions, Example, and Conclusion

Assumptions

  • When CO2 is mixed with brine saturated with methane, the CO2 will dissolve and the methane will come out of solution as methane gas.

  • The methane gas will flow to the top of the aquifer, and form a gas cap. Part of this gas can be produced from wells completed in the gas cap. About 1/3rd could be recovered.

    Example

    The total in-place volume of methane for Tertiary sandstones below 8,000 feet in the Texas Gulf Coast on short is 690 TCF. 1/3rd could be recovered, or ~ 230 TCF. Of the order of 170 Gt of CO2 would be need to be injected to recover this volume of methane.

    Conclusion

    Methane produced by CO2 injection can be used to generate electricity, thus offsetting the cost of capture and pressurization. Methane combustion produces about half the CO2 from combustion of coal, so that a net 50% reduction of CO2 results, with a concomitant reduction in cost.


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Game Changer #2: Electrical Energy Storage

Imagine:•Solar and wind providing over 30% of electricity consumed in U.S.

•The number of all-electric/plug-in hybrid vehicles on the road exceeding gasoline-powered vehicles

  • Many renewable energy sources such as wind and solar are intermittent — To make these energy sources truly effective and integrate them into the electrical grid, we need significant breakthroughs in electrical energy storage technologies.

  • Electrical energy storage (EES) devices with substantially higher energy and power densities and faster recharge times are needed if all-electric/plug-in hybrid vehicles are to be deployed broadly.

  • EES devices: batteries—store energy in chemical reactants capable of generating charge; electrochemical capacitors—store energy directly as charge.

  • Fundamental gaps exist in understanding the atomic- and molecular-level processes that govern operation, performance limitations, and failure of these devices.

Energy and power densities of various energy storage devices. Electrochemical capacitors bridge between batteries and conventional capacitors.

9


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LiFePO4 structural model and nanostructure

Ion solvation changes with pore size during electric double layer charging (electrode, black; solvent, blue; cation, orange; anion, red)

Basic Research Needs for Electrical Energy Storage

Knowledge gained from basic research in chemical and materials sciences is needed to surmount the significant challenges of creating radical improvements for electrical energy storage devices for transportation use, and to take advantage of large but transient energy sources such as solar and wind.

  • Nanostructured electrodes with tailored architectures

    Fundamental studies of the electronic conductivity of LiFePO4 led to the discovery of doping-induced conductivity increases of eight orders of magnitude. This research discovery led to the development of high power-density Li-ion batteries by A123 Systems to power electric vehicles such as the Chevy Volt and the Th!nk.

  • The promise of higher battery power via conversion reactions

    Current batteries operate with slightly less than one electron per redox center with typical electrode materials. New research on conversion reactions is looking at advanced materials to yield up to six electrons per redox center, allowing a large increase in battery power density. An example of such a reaction using cobalt is: CoO2 + 2 e + 2 Li+CoO + Li2O. Other reactions using sulfides, phosphides and flourides are being investigated.

  • Multifunctional material architectures for ultracapacitors:

    Basic research in materials for capacitors is enabling the development of multi-functional nanoporous structures and facilitating the understanding of charge storage mechanisms at surfaces. Ultracapacitors complement battery power by allowing very rapid charge and discharge cycles and the high surface area of nanostructures yields high charge storage capacity.

  • Understanding behavior in confined spaces:

    The behavior of electrolytes as a function of pore size in electric double layer capacitors is not well understood but crucial to enabling higher charge densities. Nanometer-scale pores offer high surface areas but create an increased importance of the Helmholz layer in the overall capacitance and affect the dynamics of the charge cycle.

10


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Game Changer #3: Bioenergy

Imagine:•A sustainable, carbon-neutral biofuels economy that meets over 30% of U.S.transportation fuel needs (cars and trucks) without competing with food, feed, or export demands.

  • The development of biofuels—especially lignocellulose biofuels—represents a major scientific opportunity that can strengthen U.S. energy security and protect the global environment.

  • Biofuels can be essentially carbon-neutral or even carbon-negative – as plant feedstocks grow, they reabsorb the carbon dioxide emitted when biofuels are burned, and they can store carbon dioxide in their roots.

  • To produce lignocellulosic biofuels, or biofuels from plant fiber, cost-effectively on a commercial scale will require transformational breakthroughs in basic science focused on both plants and microorganisms and processing methods.

  • The challenge is the recalcitrance of the plant cell wall – plant fiber has evolved over the millennia to be extremely resistant to breakdown by biological or natural forces.

  • Many scientists believe we are within reach of major breakthroughs in developing cost-effective methods of producing liquid fuels from lignocellulose in the near- to mid- term.

  • The environmental sustainability aspects associated with bioenergy derived from feedstock crops – water, soil quality, land-use changes, genetically altered plants, carbon balance – must be addressed proactively.

11


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Game Changer #4: Hydrogen Economy

Imagine: A hydrogen economy that provides ample and sustainable energy, flexible interchange with existing energy technologies, and a diversity of end uses to produce electricity through fuel cells, and to provide hydrogen without CO2 for transportation fuels.

  • The hydrogen economy is a compelling vision, as it provides an abundant, clean, secure and flexible energy carrier. However, it does not operate as an integrated network, and it is not yet competitive with the fossil fuel economy in cost, performance, or reliability.

  • There have been significant accomplishments in basic and applied hydrogen research in the past years leading to major advances in hydrogen production, storage, and fuel cell technologies.

  • A single oil major oil company uses 1.1 billion cubic feet of hydrogen each day for generating transportation fuel. And represents about 12% of hydrogen usage for the oil industry.

  • Hydrogen is produced from methane + steam + gas shift:

    CH4 + 2H2O = 4H2 +CO2

  • Hydrogen production produces voluminous amounts of CO2, more than by directly burning fossil fuels!

Dye-Sensitized photoelectrochemical cells for solar hydrogen production via water electrolysis. The cell consists of a highly porous thin layer of titanium dioxide nanocrystal aggregates.

13

2H2 + O2® 2H2 O + electrical power + heat


Photoelectrochemical cell l.jpg

Photoelectrochemical Cell

Semiconductor

-

Ohmic contact

e

-

e

-

e

H2

O2

O2

H2

e

metal

H2O

H2O

+

H2O

H2O

h

h

Liquid

Solid

Anodic electrocatalyst

Cathodic electrocatalyst


Slide16 l.jpg

light

n-WO3

p-Si

Sunlight Driven Hydrogen Formation – No CO2

  • Traditional photoelectrochemical water splitting is limited by a cumbersome planar, two electrode configuration for light absorption and H2 and O2 generation. Current generation of semiconductors used for absorbing visible solar spectrum are intrinsically unstable. Precious metals (Pt, Pd) are needed for H2 evolution.

  • One key constraint in photon absorbers for solar energy conversion is that the samples need to be thick enough for sufficient absorption, yet pure enough for high minority carrier length and photocurrent collection.

  • New nanorod configuration was recently developed to orthogonalize the directions of light absorption and charge carrier collection, i.e. it separates longitudinal light absorption from transverse carrier diffusion to reactive surface.

  • The short diffusion paths to reaction broadens usable materials to include earth abundant, resistive semiconductors. Opposing nanorod configuration with conductive ion membrane allows for compact device with inherent separation of O2 and H2 gas.

  • High surface-to-volume ratio of nanostructure decreases current density and permits use of broad range of new metals as sites for H2 and O2 evolution.

Solar powered water splitting scheme incorporating two separate semiconductor rod-array photoelectrodes that sandwich an electronically and ionically conductive membrane.

16

Spurgeon JM, Atwater HA, Lewis NS, Journal of Physical Chemistry C, 112, 6186-6193 (2008).


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Game Changer #5: Nuclear Energy

Imagine: • Abundant fossil-free power with zero greenhouse gas emissions

• A closed fuel cycle

  • Good for both energy security and the environment:

    • Reduces Nation’s dependence on fossil fuels and imports

    • No carbon dioxide or toxic emissions

    • Energy remaining in spent fuel

  • Currently provides 20% of nation’s electricity and could provide much more

  • Key challenge is handling spent fuel – and related problem of proliferation

  • Advances in science and engineering can provide major reduction in spent fuel by “closing” fuel cycle:

    • Recycling spent fuel and burning it in fission reactors

    • Reduce toxicity and heat load

    • Reducing storage requirements by up to 90%

    • Can extend fuel supplies 100X

    • New recycling technologies could reduce nuclear materials proliferation concern

17


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Conclusion

Basic research at the University of Texas at Austin can revolutionize our approach to carbon-free energy:

#1. Carbon capture and storage

#2. Electrical energy storage

#3. Plant cellulose to fuels

#4. Production of hydrogen without CO2 generation

#5. Recycling spent fuel

Enhancing nature to achieve energy security


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