Renewable Energy Basics

Allen J. BardThe University of Texas at Austin

March 27, 2009

American Chemical Society Energy Briefing

ROLE OF RENEWABLE ENERGY

•Transportation – Fuels from biomass and coals

•Transportation – Electrification of light vehicles (hybrids and plug-ins)

•Renewable energy in electricity generation

Types of renewables

Well-established: Hydroelectric, geothermal, biomass

Near Term: Wind, solar –thermal, solar-photovoltaic

Advanced: Third generation photovoltaic, enhanced geothermal (EGS), hydrokinetic (waves, tides), solar hydrogen, mass storage

Energy Sources for Electricity 2007

U.S. Electric Net EnergyGeneration (2007)4,200 TWh (terawatt-hours)or 4.2×1015 Whor 4,200 billion kWh

U.S. Electric Net PowerAvailable (Nameplate Capacity) (2007)1.1 TW (terawatts)or 1.1×1012 Wor 1.1 billion kW

Renewable Energy Sources for Electricity 2007

Transmission & Distribution (T&D)(the Grid)

Considerations for renewables:

•Capacity factor - what percentage of the 8760 hours of the typical year the equipment will be generating electricity and at what power level relative to its full capacity.

•Dispatchability - ability to deploy electricity generators (usually in order of cost of generation) to meet demand.

•T&D

•Cost

GenerationDemand

Transmission & Distribution (T&D)(the Grid)

•Capacity factor - (without storage) wind (30-40%) ; solar ( 26-28%)•Dispatchability - Poor

Above about 20% renewables, need to have some form of electricity storage or else distributed generation.

•T&D - May require new transmission lines only used a fraction of the time. Combine with other (e.g. natural gas) generators.

GenerationDemand

Distributed

Approximate current costs of renewablesResidential electricity costs ≈ 10 cents/kWh (with no charge for waste)(~1 cent/kWh for each $10/ton CO2 - proposed $50/ton would increase to 15 cents/kWh)

Wind 6 - 8 cents/kWh

Solar thermal - 19 - 28 cents/kWh

Solar photovoltaic (Si crystal) - 46 - 70 cents/kWh

Conventional geothermal - 6.2 - 7.6 cents/kWh

Growth of Renewable Electricity (2002-2007)TotalCapacity(GW)

0

1000

500

Quick approximate calculation

1% addl. Wind=42 TWh/year

Assuming 40% cap. Factor

New nameplate power=12 GW

Assuming 2.5 MW turbines

Need 4,800 turbines/year or

13 turbines/day installed

Efficiency of photovoltaic devices

Disruptive technologies and paradigm shifts

•Third generation photovoltaics•Solar hydrogen systems•Inexpensive electricity storage systems•Hydrokinetics•Geothermal

•NEW DISCOVERIES!

Energy Information Administration www.eia.doe.gov

Energy Efficiency and Renewable Energy http://www.eere.energy.gov/

Sources of information on energy