Renewable Energy Sources

Flashcards covering key concepts related to renewable energy sources such as solar, wind, geothermal, and hydrogen energy.

Renewable Energy

Energy from sources that are replenished naturally, such as solar, wind, geothermal, and ocean energy.

Solar Energy

Energy harnessed from the sun's rays, which can be collected using passive or active methods.

Wind Power

Energy generated from the movement of air, converted to electricity by wind turbines.

Geothermal Energy

Thermal energy that arises from beneath the Earth's surface, used for heating and electricity generation.

Hydrogen Fuel Cells

Devices that convert hydrogen into electricity, producing only water as a byproduct.

Green-Collar Jobs

Employment opportunities created by the renewable energy sector, such as design and installation of energy technologies.

Passive Solar Energy Collection

Designing buildings to maximize sunlight absorption, reducing heating costs without mechanical methods.

Active Solar Energy Collection

Using devices, such as solar panels, to actively collect, store, and convert solar energy into usable forms.

Intermittent Resource

A resource, such as solar or wind energy, that can vary in availability and requires energy storage systems.

Enhanced Geothermal Systems (EGS)

A method to extract geothermal energy by injecting cold water into dry rock to produce steam.

Concentrated Solar Power (CSP)

A technology that uses mirrors to focus sunlight onto a small area to generate heat and electricity.

Wind Farms

Groups of wind turbines generated of renewable energy in a single location.

Energy Return on Investment (EROI)

A ratio that measures the amount of usable energy obtained from an energy resource compared to the energy expended to obtain it.

Electrolysis

A process that uses electricity to split water into hydrogen and oxygen molecules.

Pollutants

Substances that enter the environment causing harm; renewable energy sources often produce fewer pollutants.

New Renewable Energy Sources

Energy sources (sun, wind, geothermal, ocean water) that are just beginning wide-scale use, have rapidly developing technologies, and are expected to play significantly larger roles in future energy landscapes.

Historical Growth Rates of New Renewables

Wind energy has expanded at nearly 50% annually since the 1970s, and solar power has recently outpaced wind in growth rate.

Benefits of New Renewables

Reduction in air pollution; decrease in greenhouse gas emissions; diversification of energy mix for economic stability; creation of green-collar jobs.

Feed-in Tariffs

Policies, like those in Germany, that incentivize renewable energy production.

Government Mandates (Renewable Energy)

Requirements for a minimum percentage of power to come from renewable sources.

Passive Solar Energy Collection

Designing buildings to maximize sunlight absorption in winter and maintain coolness in summer, using techniques like strategic vegetation and thermal mass materials.

Active Solar Energy Collection

Involves devices to focus, move, or store solar energy, such as flat plate solar collectors heating water using sunlight.

Concentrating Solar Power (CSP)

Gathers solar energy from wide areas and focuses it on singular points to heat materials and generate steam for turbine operation (e.g., solar cookers, parabolic trough systems, power towers).

Photovoltaic Cells

Devices that convert sunlight directly into electricity through the transfer of electrons in silicon plates.

Benefits of Solar Energy

An inexhaustible energy source; requires no fuel input and minimal maintenance; potential for job creation; produces zero greenhouse gas emissions or pollutants during use.

Drawbacks of Solar Energy

Variability in sunlight between regions makes it an intermittent energy resource, requiring storage capacity for consistent supply.

Wind Power

Energy generated from air movement due to heated air masses, where wind turbines convert the mechanical energy of wind into electrical energy.

Wind Turbine Operation

Wind turns a rotor's blades, driving machinery in a nacelle; turbines yaw into changing wind directions; doubling wind velocity increases power output by eight times.

Offshore Wind Farms

Wind farms located at sea that promise greater wind speeds and less turbulence, leading to higher long-term energy potential despite higher initial development costs.

Benefits of Wind Power

A single 1-megawatt turbine can prevent significant emissions (e.g., 1500 tons of carbon dioxide); high Energy Return on Investment (EROI) of 20:1; scalability by adding more turbines.

Limitations of Wind Power

An intermittent energy source; geography influences available wind power; residents often oppose developments (NIMBY syndrome); poses risks to avian populations.

Geothermal Energy

Thermal energy derived from beneath Earth's surface, harnessed through wells drilled to heated groundwater for direct heating or electricity generation.

Ground-source Heat Pumps

Systems that utilize stable underground temperatures (around 50-60^ ext{o} ext{F} or 10-16^ ext{o} ext{C}) for efficient home heating and cooling.

Benefits of Geothermal Power

Emits smaller amounts of dissolved gases compared to fossil fuels; renewable but requires correct management to prevent depletion.

Limitations of Geothermal Power

Hot groundwater may not be sustainable over time due to Earth's crust shifts; Enhanced Geothermal Systems (EGS) that use cold water can trigger minor earthquakes.

Hydrogen Fuel Cells

Devices serving as stored power sources where hydrogen combines with oxygen to produce water, releasing energy without pollution, addressing a major obstacle for renewables: large-scale energy storage.

Hydrogen Production (Electrolysis)

Hydrogen can be produced from water through electrolysis (2H2O \rightarrow 2H2 + O_2), with the cleanliness depending on the energy source used for the process.

Electricity Production from Hydrogen

The reverse reaction of hydrolysis (2H2 + O2 \rightarrow 2H_2O) occurs in fuel cells, where the movement of electrons from hydrogen across electrodes generates electricity.

Costs and Risks of Hydrogen Fuel Cells

Transitioning to hydrogen fuel infrastructure involves significant expense for transport, storage, and distribution; potential environmental risks include hydrogen leaking into the stratosphere, which could harm ozone levels and contribute to methane's atmospheric lifespan.

Benefits of Hydrogen Fuel Cells

Hydrogen is the most abundant element in the universe; producing electricity from hydrogen generates no air pollution; high energy efficiency (35-70% of the reaction's energy can be utilized).