Lecture 06 Renewable energy

Why is nuclear not renewable?

It breaks down uranium (there’s a limited amount we have) and leaves waste

Renewable energy

energy sources that are replenished at a rate faster than they are depleted

several diversed types: hydropower, solar, wind, biomass, geothermal, others

What is the source of kinetic energy? Why is it renewable?

Solar → sunlight

hydro → the flow of water, its renewable because it’s not being depleted (it’s just water moving from top to bottom)

wind → wind blowing turbines

biomass → the burning of wood “organic material”, it’s renewable because we can regrow trees or organic material

Solar energy

sunlight hitting metal in photovoltaic cell cause electrons to be emitted when light is absorbed

pros of solar energy

low cost (both initial and recurring)

produce little pollution

ran exist in remote areas

cons of solar energy

Intermittent energy source: Duck-curve problem

space intensive

When is energy demand largest?

6pm

When is solar energy production highest?

Noon (12pm)

hydropower

Water flows through penstock from high elevation to low elevation, pushing turbine

Pros of hydropower

Stable energy

provides freshwater source

cons of hydropower

expensive

interrupts flow of river systems

susceptible to droughts

wind energy

Turbines pushed by wind, kinetic energy of spinning turbines converted to electricity

off shore process:

cool air over the water move in → land heats up faster than water → warm air over the land rises

pros of wind energy

low cost, especially onshore

land efficient, especially offshore

cons of wind energy:

Noise and aesthetics make people big mad

limited to windy places, intermittent

risk posed to migrating species and marine life

Biomass

The burning of wood or organic matter

Biomass energy

Organic material burned for fuels

pros of biomass

highly available, can make waste productive

extremely low cost

cons of biomass

Air pollution source

carbon neutrality is complicated

Geothermal energy

stream generation by pumping water down below earth’s surface

pros of Geothermal energy

Very stable energy source

Small land footprint

Safe

Cons of geothermal

expensive

highly location dependent

require drilling into the earth

2 sources of energy cheaper than fossil fuels

Solar and wind

Future renewables

Earth’s tides

Nuclei merging together (nuclear fusion)

Static electricity in water vapor

Seismic activity (earthquakes)

Problem with future renewables

These solutions don’t scale currently, but may in the future