SEE Chapter 15 and 16 Flashcards

Three fossil fuels

Coal, oil (petroleum), and natural gas

Is nuclear energy renewable? Why or why not?

No, it relies on uranium, which is a finite, non renewable resource

Why aren’t fossil fuels renewable?

They take millions of years to form and can't be replenished quickly

81% of the world’s energy and two

thirds of electricity come from Fossil fuels (coal, oil, and natural gas)

Nations with most oil, natural gas, and coal

Oil: Venezuela, Saudi Arabia; Gas: Russia, Iran; Coal: U.S., Russia, China

Net energy

Energy available after subtracting the energy used to get it

EROI (Energy Returned On Investment)

Ratio of energy gained to energy invested

U.S. oil and gas EROI over the past century

Declined

How are coal, oil, and natural gas formed?

From ancient organic matter compressed under heat and pressure over millions of years

Oil sands and tar sands

Sand and clay deposits saturated with bitumen, a heavy form of petroleum

Oil shale

Rock with kerogen that releases oil when heated

Methane hydrate

Ice

Factors determining fossil fuel extraction

Market price, technology, regulations

Proven recoverable reserve

Amount of fuel we can extract under current conditions

Crude oil

Unrefined petroleum taken from the ground

Reserves to production ratio: Oil

~50 years

Reserves to production ratio: Natural gas

~50–60 years

Reserves to production ratio: Coal

~100–150 years

Peak oil

The point when oil production reaches its highest rate before declining

Mountaintop removal mining

Blasting away mountain tops to access coal underneath

Secondary extraction

Extracting remaining oil by injecting water, gas, or chemicals

Directional drilling

Drilling at angles to access hard to reach deposits

Hydraulic fracturing (fracking)

Cracking rock formations by injecting high pressure fluid to release oil/gas

Problems with offshore drilling

Risk of oil spills and hard to control accidents

Impact of Deepwater Horizon and Exxon Valdez

Major spills causing long term environmental and wildlife damage

Problems with Arctic drilling

Harsh conditions, fragile ecosystems, spill response challenges

Keystone pipeline and Keystone XL

Pipelines to transport Canadian oil; controversial for environmental reasons

Problems with oil transport

Spills, leaks, explosions, and environmental damage

Clean coal technologies

Methods to reduce coal emissions (e.g., scrubbers, gasification)

Carbon capture and storage

Capturing CO₂ emissions and storing them underground to reduce pollution

Energy efficiency

Using less energy to perform the same task

Energy conservation

Reducing total energy use by changing habits or technology

Energy intensity

Energy use per unit of economic output

Two routes to energy conservation

Improved technology and behavioral changes

Cogeneration

Generating electricity and capturing the heat for other uses

EnergyGuide labels

Labels showing appliance energy use and cost estimates

Energy Star label

A certification for high energy efficiency products

CAFÉ standards

Regulations for fuel efficiency in vehicles

True cost of gasoline to society

Several dollars more per gallon when including environmental and health costs

Rebound effect

Using more energy because efficiency makes it cheaper to use

Nuclear energy

Energy from splitting atomic nuclei

Nuclear fission

Process of splitting an atom’s nucleus to release energy

Does nuclear power emit greenhouse gases?

Very little; mostly emission free during operation

Problems with nuclear energy

Radioactive waste, cost, accident risks, limited uranium

Three Mile Island, Chernobyl, Fukushima

Nuclear accidents with varying impacts: TMI (partial meltdown), Chernobyl (explosion), Fukushima (tsunami induced meltdown)

Half life of uranium 235

About 703.8 million years

New Renewable Sources

Energy sources like solar, wind, geothermal, and ocean power that are just beginning to be used widely

Benefits of Renewable Energy

Reduction in air pollution, reduction in greenhouse gas emissions, energy mix diversification, and creation of green collar jobs

Old vs. New Renewables

Old = hydropower and biomass; New = solar, wind, geothermal, ocean energy

Environmental Impact of Renewables

Produce fewer greenhouse gases and pollutants compared to fossil fuels

Cost of Renewables

Becoming more cost competitive with fossil fuels over time

Policies Supporting Renewables

Include feed in tariffs, goals/mandates, R\&D funding, lending programs, tax credits, and rebates

Feed in Tariffs

Require utilities to purchase energy from consumers who generate it

Passive Solar Design

Designing buildings to absorb sunlight in winter and stay cool in summer without using machinery

Active Solar Technology

Uses machinery like solar collectors and PV cells to collect and convert solar energy

Photovoltaic (PV) Cells

Convert sunlight directly into electrical energy via electron transfer in silicon plates

Concentrated Solar Power

Focuses solar energy onto a single point using mirrors or lenses

Solar Cookers

Portable devices that use reflectors to focus sunlight for cooking

Net Metering

Allows consumers to subtract the value of energy they generate from their utility bill

Solar Energy Benefits

Inexhaustible, no fuel needed, low maintenance, no pollutants, creates green jobs

Drawbacks of Solar Energy

Not all regions are sunny, high upfront costs, and inconsistent supply without storage

Germany Goes Solar

Over 6% of electricity from solar, reduced CO₂ emissions by 25%, shut down 7 of 15 nuclear plants

Wind Power

Uses turbines to convert moving air into electrical energy

Wind Farms

Groups of turbines built in one area to increase electricity generation

Wind Speed and Power Output

Doubling wind speed increases power output by 8 times

Offshore Wind Sites

Have higher, more consistent wind speeds, but higher initial costs

Wind Turbine Efficiency

Produce 20 times more energy than they consume

Limitations of Wind Power

Ideal locations may be remote, and turbines can threaten wildlife and face public resistance

Geothermal Energy

Heat from Earth’s interior used for electricity or direct heating

Ground Source Heat Pumps

Transfer heat from underground where temperatures are stable year

Cons of Geothermal Energy

Can be depleted if overused, may cause earthquakes, limited suitable locations

Tidal Energy

Harnessed from coastal areas with high differences in tide levels

Ocean Thermal Energy Conversion (OTEC)

Uses the temperature difference between surface and deep ocean water to generate power

Hydroelectric Power

Uses flowing water to turn turbines and generate electricity

Storage Hydropower

Stores water in a dam and releases it to generate electricity when needed

Run of River Hydropower

Diverts river flow without large reservoirs

Pumped Storage Hydropower

Pumps water uphill during low demand and releases it downhill to generate power during high demand

Advantages of Hydropower

Renewable, highly efficient (EROI 80:1), no greenhouse gas emissions

Environmental Impacts of Hydropower

Alters habitats, traps sediment, changes water temperature, blocks fish migration

Limits to Hydropower Expansion

Most major rivers are already dammed

Bioenergy

Energy from biomass, such as plant and animal material

Sources of Biomass

Includes wood, crop residues, charcoal, and animal waste

Uses of Bioenergy

Direct combustion, electricity generation, landfill gas, biofuels

Traditional Biomass

Firewood, dung, and charcoal still used by over a billion people

Biopower

Electricity generation from biomass, often using waste products or mixed with coal

Gasification

Converts biomass into gas for turbines through heating

Biofuels

Liquid fuels like ethanol and biodiesel made from biomass

Ethanol Production

USA uses corn; Brazil uses sugar cane

EROI of Corn Ethanol

Approximately 3:1

Biodiesel

Made from vegetable oil, grease, or animal fat; cleaner emissions and biodegradable

EROI of Biodiesel

Approximately 2:1

Future of Biofuels

Algae and cellulosic ethanol offer more sustainable options

Carbon Neutrality of Biomass

Ideally carbon neutral since CO₂ released equals what plants absorbed

Biofuel Reality

May compete with food supply, require fossil inputs, and not always truly carbon neutral

Hydrogen Energy

Releases energy when combining with oxygen, producing only water

Fuel Cells

Highly efficient devices (35–70%) that generate electricity from hydrogen

Electrolysis

Splits water into hydrogen and oxygen using electricity

Sources of Hydrogen

Can be generated from water, fossil fuels, or biomass

Challenges of Hydrogen

Dependent on energy source, lacks infrastructure, and may have negative net energy