Sustainable Energy: Challenges and Solutions

STEM Scholars Lecture Series

California State University Sacramento

February 27, 2007

Sustainability

“Meeting the needs of the present without compromising the ability of future generations to meet their needs.”

Criteria for Sustainable Energy:

1. Fuel Supply not Depleted with Use

2. Properties of Earth/Atmosphere Unaltered

3. No Significant Social Injustices

Energy Supply

Hydro 3%

Nuclear 9%

Natural Gas 20%

Coal 24%

Petroleum 41%

Renewables 3%

320,000,000,000 Gallons of Petroleum

1,000,000,000 Tons of Coal

22,000,000,000,000 Cubic Feet Natural Gas

36% Imported (Petroleum and Natural Gas)

85% From Fossil Fuels

Energy Lifecycle: Automobile

H2O

CO2

CO2 NOX

H2O CO

Energy (Transportation)

Energy Lifecycle: Automobile

NOX + VOC + Sunlight = Ground Level Ozone

CO2

H2O

Combustion Products

C8H18 + 12.5 (O2 + 3.76 N2)

8 CO2 + 9 H2O + 47 N2

1 kmol fuel 8 kmol CO2

1 kg fuel 3+ kg CO2

One 16 gallon tank 320 lbs CO2

U.S. CO2 Emissions = 6.5 Billion Tons

Worldwide CO2 = 30 Billion Tons

Combustion Products

Global CO2 Concentrations

Data from Mauna Loa Observatory, Hawaii

Climate Change

Short Wavelength

High Energy

Long Wavelength, Low Energy

11 of Last 12 Years Rank Among the 12 of the Warmest Since 1850

Average Temperature Risen 1.5F Since 1900

Sea Levels Have Risen 7 inches in the Last Century

CO2

CO2

Climate Change

So it’s a Little Warmer, What’s the Big Deal?

1. Avg. Temp. to Increase 3 to 9 F by 2100 2. Oceans to Rise 7 to 31 Inches by 21003. More Frequent and Stronger Hurricanes4. Extreme Weather5. Ecosystems and Habitat Loss6. Glacier Retreat 7. Economic Impacts

Climate Change

February 2002 March 2002

Larsen B Ice Shelf – 200 m thick, 3200 km2

Climate Change

February 17, 1993 February 21, 2000

Receding Snows of Mount Kilimanjaro, Tanzania, AfricaExpected to Be Gone By 2020

Image courtesy of the Image Science & Analysis Laboratory, NASA Johnson Space Center

Sociopolitical Injustices?

Photos courtesy of Associated Press and Emirates Palace, Abu Dhabi

Fossil Fuel Sustainability

Depleting Fuel Reserves• Best Estimate: 40-80 years

• Undiscovered Reserves Uncertain• Proven Reserves Uncertain (OPEC)

• What is Certain?• Demand Increasing• Supply Decreasing

Atmospheric CO2 Concentration Increasing

Economic, National Security Issues

Renewable Technologies

Renewable Technologies• Direct Solar Thermal and PV• Indirect Solar

• Biomass• Wind• Wave

• Other Sources• Geothermal• Tidal

Active –Solar Collector, RooftopsPassive – Integrating Low Energy Design

Solar Thermal

Domestic Hot Water

Pools/Spas

Residential Space Heating

Adsorption Refrigeration

Industry/Processing

Solar Collectors

Water

Black Absorber(0-10C Rise)

Flat Plate Collector(0-50 C Rise)

Glass

Insulation

Evacuated Heat Pipe(10-100 C Rise)

Water

Focused Collector(50-150 C Rise)

Solar Collectors

Evacuated Heat Pipe Water Heater

Passive Solar Heating

Warm

Cool

Trombe WallConservatory

Warm

Outside Air

Solar Photovoltaic

Antireflective Coating

n-type Semiconductor

p-type Semiconductor

Backing-+

+ +++---

Photons

Solar Summary

Benefits• Simplicity• Availability vs. Demand: Peak-Summer• Cost-effectiveness

Challenges• Intermittent and Little Availability in Winter• Energy, Cost of PV Cell Production

What’s Next?• Widespread Use• New PV Applications (Thin Film, Flexible)

Bioenergy

Biomass – All of the Earth’s Living MatterBiofuels – Fuels Derived from Biomass

CO2 Heat and ElectricityCO2Bioenergy

CO2 Low Temperature Heat

CO2

Respiration

Bioenergy

Traditional – Combustion of Raw Biomass“New” – Transform Properties (Liquid, Gas)

• Utilize Waste and Replace Fossil Fuels• Reduce Pollutant Emissions

Examples• Woody Crops – Forestry• Agricultural – Switch Grass, Corn, Oil Seeds• Wastes

• Agricultural (Rice Husks, Corn Shucks, etc)• Animal (Dairy, Sewage)• Commercial (Sawdust, Tires, Landfill Gas)

Abengoa Bioenergy Facility in York County, NebraskaEthanol Production Capacity: 50 Million Tons per Year

Biofuels: Ethanol

Benefits• Availability

• World’s Biomass Energy Storage 95 TW• World’s Energy Consumption 15 TW

• Existing Equipment, Infrastructure• Waste Utilization, Potentially Carbon Neutral• Scheduling Control

Challenges• Energy Balance and Economics• Improve “New” Biofuel Processes• Increase Production Capacity

Bioenergy Summary

Sun Heats Earth Unevenly• Buoyancy• Regional Pressure Differences

Wind Energy

Ocean Land

Wind

The Aerofoil

Wind Energy

Wind Turbines• Lift and/or Drag Forces in Direction of

Rotation• Vertical or Horizontal Axis• Most Common: 3-Bladed, Horizontal Axis• Typical Efficiencies: 20-30%

Wind Energy

Wind Turbines or Bird Blenders?

Avian Deaths (U.S. per Year)• Wind Turbines: 30,000• Communications Towers: 40 Million • Pesticides: 67 Million • Vehicles: 70 Million• Cats: 100 Million• Utility Lines: 150 Million• Windows: 500 Million

Altamont: Location, Tower Design, Spacing

Wind Energy

SMUD Solano Wind Project, Rio Vista, CA

Benefits• Economical

• High Initial Investment• Low Maintenance, No Fuel Costs

• Minimal Air, Water, Land Pollution• Scalability (1 kW to 3 MW)• Many “Good” Locations

Challenges• Visual Pollution• Intermittency and Predictability

Wind Energy Summary

Wave EnergyWinds Turbulent Air Flow

Wind Flow on Upwind Wave Faces

Shear Stress on Surface of Water

Solar Radiation Wind Waves

Wave Size Factors1. Wind Speed2. Wind Duration3. Distance Over Which Wave Travels

Wave Energy

Oscillating Water Column (OWC)

Wave Energy

The 500 kW LIMPET OWC, New Zealand

Wave Energy

Pelamis (Sea Snake)

Hydraulic Rams Pump High Pressure Fluid

Accumulated Fluid Drives Turbines, Generators

A Few Other IdeasWhale Frog Dragon

Clam Swan

Wave Energy

The 750 kW Pelamis Wave Energy Converter, Portugal

Wave Energy

Benefits• Waves = Concentrated Solar Energy• Demand in Phase with Availability (Winter)• Low/No Chemical Pollution• Low Visual Pollution (Offshore)• Large Potential Resource (Estimated 2 TW)

Challenges• Electricity Transmission• Immature Technology• Potential Shipping, Boating Accidents

Tidal Energy

Maximum Gravitational Force: High Tide

Gravitational Force• Proportional to Mass of Earth, Moon• Inversely Proportional to Distance Squared

Minimum Gravitational Force

Tidal Energy

Minimum Centrifugal Force

Centrifugal Force• Earth-Moon System• “Spinning Through Space”

Maximum Centrifugal Force: High Tide

Center of Mass

Tidal Energy

Ocean Reservoir

Flood Generation

Ocean Reservoir

Ebb Generation

h h

Large Generating Capacity (Many MW)Two Large 3.0 to 5.0 Hour Bursts per DayFour Smaller 1.5-3.0 Hour Bursts per Day

Tidal Energy

Tidal Barrage at La Rance, France

240 MW Capacity333 m Long

8 m Tidal Range

Tidal Energy

Benefits• Tremendous Electricity Generation Potential• No Green House Gas, Pollutant Emissions• Predictable

Challenges• Environmental Impact

• Modifying Water Levels Behind Dam• Less Variation, Affecting Birds and Fish

• Shipping, Boating• Tremendous Initial Cost• Intermittency

Independent of the SunRadioactive Isotopes, Gravitational Energy

Geothermal Energy

340 W/m2

Impermeable Rock

Impermeable Rock

Liquid Hot Magma

Water

0.05 W/m2

Impermeable Rock

Steam

Water

Hot Springs

Geothermal Plant

Many Possible Configurations

Geothermal Energy

Flash Chamber

Cooling Tower

Generator

Steam Turbine

Heating, Processing

Electricity to Grid

Geothermal Energy

One of twenty-one plants at the Geysers, Sonoma and Lake Counties, CAThe Geysers Provides 850 MW to Power about 750,000 Homes

Geothermal Energy

Benefits• No Intermittency• Low/Zero Pollutant Emissions

Challenges• Source Depleted (Energy Mining)

• 250:1 Use to Recharge Rate• Limited Sources

• High Quality Sources Tapped• Most Near Tectonic Plate Interfaces

• Better Utilize Low Quality Sources• Ground Source Heat Pump

How do we get Sustainable?

As Citizens• Reduce, Reuse, Recycle

• Drive a Fuel Efficient Car

• Don’t Drive (Telecommute, Public Trans)

• Make Your Home Energy Efficient• Insulation, Caulking and Door Seals• Tune Heater and Air Conditioner• High Efficiency Appliances and Lights• Install Renewables

• Plant Trees

How do we get Sustainable?

As Scientists, Engineers and Mathematicians• Traditional Technologies

• Efficient Gasoline and Diesel Vehicles• Cogeneration and Carbon Sequestration• Energy Efficiency and Management

• Research, Develop Emerging Technologies• New Biofuel Sources• Fuel Cells and Hydrogen• New Technologies and Applications

• Bring Sustainable Products to Market• Transparent, Cost Effective

Sacramento State Expertise

Solar Thermal• Solar Heating and Adsorption Refrigeration• Efficient Building Design

Biofuels and Combustion• Conversion of Biomass to Alcohol Fuels• Mesoscale and Distributed Power Systems• Ultra-Low Emissions Combustion

Stationary Power Fuel Cells• New Fuel Cell Types• Parametric Study and Computer Simulation

Clean Energy Center

Internal – Student Learning through ResearchExternal – Regional Clean Energy Growth

Mission: Contribute to Sustainable Energy in the Sacramento Region with Education and Research

Goals• Promote Collaboration within Sac State• Foster External Relationships• Facilitate External Funding and Publication• Create Authentic Learning Experiences• Provide Technical Expertise to Startups

Photo Credits

John GilardiSMUDGeneral MotorsNASAEmirates PalaceSolar Innovations, IncAbengoa BioenergyWavegen: Voith Siemens Hydro Power Generation Ocean Power Delivery, Ltd.Icelandic National Energy AuthorityCalpine, Corp.