Renewable Energy Sources and Smart Energy Solutions

Posted on Mar 14, 2025 in Geology

Engineering Portion

Causes of Wind

Atmospheric pressure differences (pressure = Force/area). Average pressure at sea level: 1 atm = 29.92 inHg = 14.7 psi.

Types of Windmills

  • Small (<10 kW) – Home, farm, remote applications (telecommunications, water pumping)
  • Medium (10-250 kW) – Village, hybrid, distributed power
  • Large (250 kW-2 MW) – Central wind farms, distributed power

Factors Affecting Wind Power Generation

In order of importance: [Power in wind = 1/2ρAV3] A = Swept area (πR2); V = Wind speed; ρ = density of air

  1. Wind Speed
  2. Swept Area
  3. Rotor Efficiency
  4. Generator Efficiency
  5. Electrical Efficiency

Geothermal Energy

Heat flow < 5km below surface.

Uses

Space heating, aquaculture, food dehydration, electricity production.

Geothermal heat is generated by decaying radioactive elements.

Advantages of Geothermal Energy

  • Low emissions
  • Safe and reliable
  • Immune to weather conditions
  • Cost-effective over the life of the plant
  • Sustainable, small footprint
  • No fuel cost

Disadvantages of Geothermal Energy

  • High initial cost
  • Risk of seismic activity
  • Location sensitive
  • Risk of overexploiting the resource

Types of Geothermal Plants

Dry steam, Liquid Flash (>150C), Binary

Nuclear Energy

Fission and fusion reactions (nuclear reactor permits a controlled fission reaction using U-235 or other heavy elements).

Two Types of Reactors

  • PWR (Pressurized Water Reactor) – Keeps water under pressure so it heats but does not boil. Steam for the turbine is in separate piping.
  • BWR (Boiling Water Reactor) – Direct contact boils water to steam for the turbine.

Fuel Rods

Uranium

Control Rods

Cadmium, Boron, Graphite, and other non-fissionable materials. These control the rate of reaction by absorbing neutrons.

Light Water Reactors (PWR and BWR) make up 90% of reactors (BWR is 20% of the world’s reactors).

Nuclear energy is currently 20% of US electricity, with 104 operating nuclear plants.

Advantages of Nuclear Energy

  • Rich energy source
  • 1 gram of U-235 = 3.5 tons of Coal
  • Reactors run for long periods with no shutdown or maintenance
  • No pollution

Disadvantages of Nuclear Energy

  • Produces radioactive waste; no long-term disposal
  • Not much U-235 (100-200 year supply)
  • Expensive to build plants
  • Safety risk
  • Minor maintenance is usually a big process

Half-Life in Relation to Nuclear Power

The amount of time to decay half of the atoms in an element.

After 10 half-lives, an element is usually harmless.

The longer the half-life, the less intense the radiation.

Half-lives range from a fraction of a second to 4.5 billion years (U-235).

Biomass Energy

Garbage, corn, wood, landfill gas, alcohol.

Energy Crops

Woody crops, agricultural crops.

Waste Products

Wood residues, temperate crop waste, animal waste, municipal solid waste.

Ethanol

Fermentation of starches/sugars, cellulosic fermentation.

Biodiesel

Organic oils combined with alcohols, Ethyl + methyl esters.

Biochemical Conversion – Sugar Platform

  1. Biomass to sugar
  2. Ferment intermediates (yeast/bacteria)
  3. Process fermentation product (yield fuel-grade ethanol and other fuels, chemicals, heat, or electricity)

Thermochemical Platform

  • Combustion, Gasification, Pyrolysis

Efficiency

Efficiency of biomass to petroleum = 45% Lower than petroleum and coal.

Benefits of Biomass Energy

  • Decrease in greenhouse gas emissions
  • Can be renewable (cell growth, etc.)
  • Crops create habitat, increasing biodiversity
  • Environmentally sound energy option for developing nations

Smart House

(Energy efficiency as a renewable source)

  • Energy-efficient thermostats, appliances, and controls
  • Solar and other green power sources for supplemental energy
  • On-board intelligence to control usage during peak power plant times

LED Lighting

  • Lasts 100,000 hours, low maintenance, energy-efficient, superior color range, solid-state technology, dynamic color
  • No mercury, low heat and UV output, cold start, low voltage

Insulation

R-value is a material’s ability to resist heat flow. Higher R-value = Higher insulation.

Smart Grid

Use of computers and technology to transmit energy more efficiently.