BRAE 348

What is the Law of Conservation of Energy?

Energy cannot be created or destroyed — only converted from one form to another.

What are the 'big six' forms of energy?

Mechanical, thermal, chemical, electrical, radiant (light), and nuclear energy.

What is the difference between renewable and non-renewable energy?

Renewable sources naturally replenish (sun, wind, water); non-renewable sources exist in finite amounts and are depleted when used (coal, oil, gas).

What is the formula for Power?

Power = Energy ÷ Time (P = E/t). Measured in Watts (W).

What is the difference between potential and kinetic energy?

Potential energy is stored energy (position/condition); kinetic energy is energy of motion.

What are the three temperature scales and how do you convert Celsius to Kelvin?

Fahrenheit, Celsius, and Kelvin. K = °C + 273.15

What is the specific heat capacity of water?

4,186 J/(kg·°C) — water requires more energy to heat than most substances.

What is efficiency in energy systems?

Efficiency = (useful energy output ÷ total energy input) × 100%. No real system is 100% efficient.

What is the electromagnetic spectrum in order of energy?

Radio

How does a photovoltaic (PV) cell work?

Photons knock electrons loose in a semiconductor (usually silicon), creating an electric current via the photovoltaic effect.

What is the typical efficiency range of commercial PV panels?

Most commercial panels are 15–22% efficient.

What are the three main types of PV panels?

Monocrystalline (highest efficiency), polycrystalline (moderate), and thin-film (lowest efficiency, flexible).

What is Concentrated Solar Power (CSP)?

CSP uses mirrors or lenses to focus sunlight onto a heat exchanger, producing steam to drive a turbine and generate electricity.

What is net metering in solar grid integration?

A billing system that credits solar panel owners for excess electricity fed back to the grid.

What is the wind power equation?

P = ½ρAv³ — Power = half × air density × swept area × wind speed cubed.

Why does wind power increase with the cube of wind speed?

Doubling wind speed increases power by a factor of 8 (2³), making site wind speed critically important.

What is the Betz Limit?

The theoretical maximum efficiency of a wind turbine is ~59.3% — you can never capture 100% of wind energy.

What are the two main types of wind turbines?

Horizontal-axis wind turbines (HAWT) — most common; and vertical-axis wind turbines (VAWT).

What factors affect wind turbine energy output?

Wind speed, air density, rotor diameter, turbine height, local terrain, and wake effects from neighboring turbines.

What is nuclear fission?

The splitting of a heavy atomic nucleus (e.g., U-235) into smaller nuclei, releasing a large amount of energy.

What is a moderator in a nuclear reactor?

A material (e.g., water, graphite) that slows neutrons so they can sustain the fission chain reaction.

What is the nuclear fuel cycle?

The series of steps from uranium mining

What is the role of control rods in a reactor?

Control rods absorb neutrons to regulate reaction rate and shut down the reactor if needed.

What are the main challenges of nuclear waste management?

High-level radioactive waste remains dangerous for thousands of years and requires secure long-term geological storage.

What is DCPP?

Diablo Canyon Power Plant — California's last operating nuclear plant, located near San Luis Obispo.

What is the basic principle of hydropower?

Converting the potential energy of water at height into kinetic energy, then into electricity via a turbine and generator.

Name three types of hydropower systems.

Reservoir (impoundment), run-of-river, and pumped-storage hydropower.

What is pumped-storage hydropower?

Water is pumped uphill when electricity is cheap/surplus, then released downhill to generate power when demand is high — acts as a giant battery.

What factors affect hydropower output?

Head (height of water fall), flow rate (volume of water), and turbine/generator efficiency.

What is OTEC?

Ocean Thermal Energy Conversion — uses the temperature difference between warm surface water and cold deep ocean water to generate electricity.

What is the difference between tidal and wave energy?

Tidal energy comes from gravitational forces of the moon/sun causing predictable tides; wave energy comes from wind-driven surface waves.

What is geothermal energy?

Heat extracted from the Earth's interior (from radioactive decay and residual formation heat) used for electricity and direct heating.

What is a heat pump and how does it work?

A heat pump moves heat from a cooler space to a warmer one using a refrigerant cycle — it can heat or cool a building very efficiently.

What is the COP of a heat pump?

Coefficient of Performance = useful heat output ÷ electrical energy input. Heat pumps typically have a COP of 3–5 (300–500% 'efficiency').

What are the main 'colors' of hydrogen?

Green (electrolysis with renewables), blue (natural gas + CCS), grey (natural gas, no CCS), and black/brown (coal gasification).

How does a hydrogen fuel cell work?

Hydrogen and oxygen react electrochemically to produce electricity, with water as the only byproduct.

What is the difference between biodiesel and bioethanol?

Biodiesel replaces diesel fuel and is made from oils/fats (transesterification); bioethanol replaces gasoline and is made by fermenting sugars/starches.

What is a lithium-ion battery and its main components?

A rechargeable battery with a lithium-based cathode, graphite anode, and lithium-salt electrolyte — charge moves via lithium-ion migration.

Name three grid-scale energy storage technologies.

Pumped hydro, lithium-ion battery arrays, and compressed air energy storage (CAES).

What is the greenhouse effect?

Greenhouse gases (CO₂, CH₄, H₂O) trap outgoing infrared radiation from Earth's surface, warming the atmosphere.

What role does methane play in climate change?

Methane (CH₄) is a potent greenhouse gas — ~80× more warming than CO₂ over 20 years — from agriculture, landfills, and fossil fuel extraction.

How did the Industrial Revolution change the carbon cycle?

Mass burning of fossil fuels released carbon stored underground for millions of years into the atmosphere, raising CO₂ concentrations rapidly.

What is the difference between passive and active remote sensing?

Passive sensors detect natural energy (e.g., reflected sunlight); active sensors emit their own energy (e.g., radar, LiDAR) and measure the return.

What is multispectral sensing used for in agriculture?

Detecting crop health, stress, moisture, and vegetation indices (like NDVI) by measuring reflectance across multiple wavelength bands.

What is a technosignature?

Observable evidence of technology — originally used to describe signs of extraterrestrial civilization, but also refers to human technological impact on Earth's systems.

What are the key tradeoffs in energy transitions?

Cost, reliability, land use, material extraction, environmental impact, energy security, and equity — no single source is perfect.

What does the EIA stand for and what does it do?

US Energy Information Administration — collects, analyzes, and publishes energy data and forecasts for the United States.