Energy Resources and Solid Waste Management

Vocabulary practice flashcards covering renewable and nonrenewable energy technologies, half-life decay, municipal solid waste management, landfill engineering, recycling systems, and federal waste statutes.

Nuclear Fission

A process in which a neutron is fired into the nucleus of an unstable radioactive isotope, such as $\text{Uranium-235}$, causing the nucleus to split and release large amounts of heat energy plus additional neutrons that initiate a chain reaction.

Radioactive Half-Life

The amount of time required for $50\%$ of a radioactive substance to decay or break down (for example, the half-life of $\text{Cobalt-60}$ is $5.27\,\text{yrs}$).

E85 (Flex Fuel)

A fuel mixture consisting of $51\%\text{--}83\%$ ethanol blended with gasoline that is used in flex-fuel vehicles to reduce petroleum consumption, though it is less efficient than pure gasoline.

Biodiesel

A liquid fuel produced specifically from plant oils such as soy, canola, or palm oil; palm oil biodiesel can generate $98\%$ more greenhouse gases than fossil fuels due to forest clearing for plantations.

Passive Solar Heating

The practice of absorbing or blocking solar heat directly without using mechanical or electrical equipment, relying on architectural features such as building orientation, south-facing windows with roof overhangs, shade trees, and heat-absorbing flooring.

Active Solar Heating

The use of mechanical or electrical equipment, such as solar water heaters or circulating pumps, to capture the sun's thermal energy or convert solar radiation directly into usable electricity.

Photovoltaic (PV) Cell

A semiconductor device (usually made of silicon) that generates direct electrical current when incoming photons cause charges to separate across n-type and p-type layers, causing electrons to flow through an external circuit.

Concentrated Solar Thermal (CST)

An active solar technology that uses fields of sun-tracking mirrors called heliostats to focus sunlight onto a central tower receiver to heat water or molten salt into high-pressure steam that drives a turbine and generator.

Heliostat

A motorized mirror that tracks the sun throughout the day, reflecting and concentrating sunlight directly onto a central solar receiver in a concentrated solar thermal power plant.

Water Impoundment Dam

A hydroelectric infrastructure built across a river to create a large reservoir upstream, allowing operators to regulate water flow through internal penstocks to turn turbines and drive electrical generators.

Fish Ladder

A stepped series of ascending pools built alongside or through a dam that allows migratory fish, such as salmon, to swim upstream around the barrier to reach their spawning grounds.

Run-of-River System

A hydroelectric method where a diversion weir routes a portion of a river's natural current through an adjacent channel to spin a turbine, avoiding reservoir flooding upstream and allowing natural sediment transport downstream.

Tidal Power

A form of renewable energy generation that relies on the natural ebb and surge of coastal ocean tides passing through underwater turbines in a barrage; it is geographically limited to coastal zones.

Geothermal Energy

Energy harnessed by drilling into naturally heated underground reservoirs or rock layers warmed by magma convection and radioactive decay in Earth's mantle, bringing steam or hot water to the surface to drive turbines.

Hydrogen Fuel Cell

An electrochemical device that converts hydrogen gas ($\text{H}_2$) and oxygen ($\text{O}_2$) into electricity by using an electrolyte membrane to split $\text{H}_2$ into protons ($\text{H}^+$) and electrons ($\text{e}^-$), releasing only water vapor ($\text{H}_2\text{O}$) as a byproduct.

Capacity Factor

The fraction or percentage of total potential energy an electrical generating unit produces over a specific timeframe (for example, wind turbines typically operate with an average capacity factor of $15\%\text{--}30\%$).

Municipal Solid Waste (MSW)

Everyday refuse, trash, garbage, or litter generated solely by human activities within households, businesses, and institutions, consisting of approximately $\frac{1}{3}$ paper and $\frac{2}{3}$ compostable organic matter.

E-Waste

Discarded electronic items, such as computers, televisions, tablets, and phones, which comprise approximately $2\%$ of MSW and contain toxic heavy metals (lead, mercury, cadmium) as well as PBDE fire retardants.

Sanitary Landfill

An engineered waste disposal site designed with specific barrier and recovery systems (impermeable bottom liner, leachate collection pipes, methane extraction wells, and a clay cap) to isolate trash from the surrounding ecosystem.

Leachate

Contaminated liquid formed when precipitation filters down through landfill waste, dissolving and extracting toxic chemicals, heavy metals, organic acids, and pathogenic bacteria.

Leachate Collection System

A network of perforated drainage pipes positioned over an impermeable clay or plastic liner at the base of a sanitary landfill to collect toxic wastewater for subsequent treatment and disposal.

Methane Recovery System

A configuration of drilled wells and pipes embedded in a sanitary landfill that captures methane gas ($\text{CH}_4$) produced by anaerobic decomposition so it can be burned to produce electricity or heat.

Clay Cap

A compacted seal of clay and soil placed over a filled landfill to prevent water infiltration, retain odors, block vermin or animal intrusion, and support revegetation.

NIMBY (Not In My Back Yard)

The public attitude or political resistance by local citizens opposing the siting of unwanted, polluting, or unpleasant facilities (such as landfills or incinerators) in their direct residential vicinity.

Waste Incineration

The high-temperature combustion of municipal solid waste that reduces solid volume by approximately $90\%$ and can generate steam for electricity, but produces toxic bottom ash and releases atmospheric pollutants ($\text{CO}_2$, $\text{PM}$, $\text{SO}_x$, and $\text{NO}_x$).

Closed-Loop Recycling

A recycling process in which post-consumer material is recovered and remanufactured into the exact same original product (such as recycling clear glass bottles back into new glass bottles).

Open-Loop Recycling

A recycling method where recyclable materials from one product are processed into an entirely different secondary product (such as converting discarded plastic polyethylene bottles into polyester fleece jackets).

Composting

The controlled aerobic biological breakdown of organic waste (food scraps, yard clippings, paper) requiring moisture, oxygenation, and an optimal carbon-to-nitrogen ratio of roughly $30:1$ (browns to greens).

Waste to Energy (WTE)

The process of generating electricity by burning combustible solid waste in an industrial furnace or combusting recovered landfill methane to heat water into steam that turns a turbine generator.

CERCLA (Superfund)

The Comprehensive Environmental Response, Compensation, and Liability Act; a federal program established to finance and oversee the emergency response and long-term cleanup of abandoned hazardous waste sites.

RCRA (Resource Conservation and Recovery Act)

A United States federal statute authorizing the EPA to regulate hazardous waste across its entire lifecycle—from generation, transportation, and treatment to storage and disposal—while an operating business is active.