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U4735x Environmental Science for Decision Makers

Lecture 14, 15 and 16: Nuclear Power and Renewable Power Resources.

Walter Pitman

List of Projections:

• Nuclear power plant.
• Schematic diagram of burner and breeder reactors.
• Schematic illustration of the sedimentary-metamorphic-igneous processes that ultimately lead to formation of uranium ore deposits.
• Mineralization occurring along a fault zone.
• Diagrammatic cross-section of a vein.
• Plot of annual reactor uranium requirement and projected uranium production capabilities.
• Amount of power produced by reactors worldwide.
• Map of world's major primary uranium deposits.
• Map of world's major secondary uranium deposits.
• Estimated supply and demand for uranium between 1980 and 2025.
• Diagrammatic representation of Earth's energy budget.
• Using wind-generated electricity to satisfy U.S. electricity demand.
• Solar-thermal electric plant, Mojave Desert.
• Solar panels.
• World map showing variation in annual mean solar energy flux.
• Solar input statistics for various countries.
• Three principal routes in the exploitation of solar energy.
• Alcohol fuels and electricity from biomass energy.
• Sources of biomass energy supplies.
• Hydrogen fuel.
• Solar energy costs, 1980-2010; cost of gasoline, methanol, and ethanol compared.

Nuclear Power.

Nuclear power plant.

²³⁸U most abundant.

²³⁵U ~ 0.7% of total uranium ore available.

1kg ²³⁸U --> 3x10³ J in a year. Spontaneous decay.

1kg coal --> 2.8x10⁷ J.

1kg of ²³⁵U = 1000/235 = 4.25 moles.

6x10²³ atoms/mole

1kg ²³⁵U has 25.5x10²³ atoms

or

8.2x10¹³ J

or

3x10¹⁰ as much energy as 1kg ²³⁸U

or

3x10⁶ as much energy as 1kg coal

But only 0.7% ²³⁵U in Uranium ore (99.3% ²³⁸U).

Breeder Reactors.

Schematic representation of the chain reaction in the fission of uranium.

35% Thermal efficiency

60% of the available atoms undergo fission.

Produces:

1kg uranium --> 1.81x10¹³ Joules.

There are an estimated

2,083,710 kg U --> 37,715,151x10¹⁵ Joules.

Total world energy consumption = 334,890x10¹⁵ Joules/year

If the Uranium were used to supply ALL our energy needs, it would last 112.6 years.

Schematic diagram of burner and breeder reactors.

Fusion Reactors.

²H + ²H --> ³He + ¹n + 3.3 Mev

1 Mev = 1.64 x 10^-13 J

7-9 charged prodects might be used to generate electricity directly.

8-9 no radioactive products: no neutrons.

Geology Of - Where Found.

1. Pegmatites and disseminated Uranium deposits.
2. Hydrothermal Vein deposits - in cracks, fissures.
3. Hydrothermal Vein deposits developed beneath ancient (Proterozoic: 2500-5700 Ma ago) unconformities.
4. Sandstone deposits related to sediments in rivers, lakes and shallow water seas.
5. Placer deposits in quartz pebbles and conglomerates.
6. Other concentrations in sediments of phosphatig limestones, marine phosphates, and black shales.

In magmatic regimes:

Uranium containing minerals were the last to crystalize and hence the first to melt.

Erosion - Burial - Magmatism Cycle.

Schematic illustration of the sedimentary-metamorphic-igneous processes that ultimately lead to formation of uranium ore deposits.

Mineralization occurring along a fault zone.

Diagrammatic cross-section of a vein.

Plot of annual reactor uranium requirement and projected uranium production capabilities.

Amount of power produced by reactors worldwide.

Map of world's major primary uranium deposits.

Map of world's major secondary uranium deposits.

Estimated supply and demand for uranium between 1980 and 2025.

Renewable Power Resources.

Diagrammatic representation of Earth's energy budget.

Hydro Power.

Hydroelectricity sites.

Hydroelectric known exploitable potential refers to that part of a country's annual gross theoretical capacity (the amount of energy that would be obtained if all flows were exploited with 100% efficiency) that could be exploited using current technology and under current and expected local economic conditions. This includes both large- and small-scale schemes. Hydroelectric technical potential refers to the annual energy potential of all sites where it is physically possible to construct dams, with no consideration of economic return or adverse effects of site development.

Installed capacity refers to the combined generating capacity of hydroelectric plants installed in the country as of December 31, 1990.

Wind.

Wind turbines.

Using wind-generated electricity to satisfy U.S. electricity demand.

Solar Power.

Solar-thermal electric plant, Mojave Desert.

Solar panels.

World map showing variation in annual mean solar energy flux.

2.16x10¹⁷ kwh/yr x 1000 x 3600 sec/hr = 0.7776x10²⁴ Joules/yr

(0.7776x10²⁴ Joules/yr) / 510x10⁶ km² = 1.525x10¹⁵ Joules/km²/yr

World uses ~3.234x10²⁰ Joules/yr

3.234x10²⁰ / 1.525x10¹⁵ = 212,066 km²

USA uses 0.808x10²⁰ Joules/yr

--> 53,016 km²

Solar input statistics for various countries.

Three principal routes in the exploitation of solar energy.

Alcohol fuels and electricity from biomass energy.

Sources of biomass energy supplies.

Hydrogen fuel.

Solar energy costs, 1980-2010; cost of gasoline, methanol, and ethanol compared.

World use of energy: 3.4x10²⁰ Joules/yr

At 200 Watts/m², 100% efficiency:

200x10⁶ x 3.15x10⁷ = 6.3x10¹⁵ Joules/km²/yr

54,000 km² required.

U.S. requires 12,700 km² at 100% efficiency.

At 10% efficiency:

world requirement: 540,000 km²

U.S. requirement: 127,000 km²

At 5% efficiency:

world requirement: 1,080,000 km²

U.S. requirement: 254,000 km²