ENSC Alternate Sources of Energy

What are the trends in world energy consumption?

energy consumption is always going up

What are two causes of this trend?

human populations increase

Per capita consumption increases as countries become more industrialized

How does the US compare to the rest of the world?

Our renewable energy consumption is less than the worldwide renewable energy consumption (we are NOT leading in renewable energy consumption/we are one of the worst)

Renewable sources - why are they referred to as “alternate” sources?

most of our energy is coming from non-renewable sources

Most energy forms (renewable and nonrenewable) are stored in forms of _ How/Why?

stormed in forms of solar energy (fossil fuels, nuclear, wind, biomass, solar, geothermal, hydroelectric, hydrogen). because they cannot exhaust the sun

3 reasons why renewable energy should be used more

1. Cannot exhaust renewable energy sources

2. Environmental protection

3. Most don’t produce greenhouse gases

4. Decentralized (energy can come from multiple locations)

Passive Solar Energy

take advantage of solar energy to accomplish a task, but don’t use any special devices (greenhouse)

Active Solar Energy

Photovoltaics (solar panels), solar thermal collectors. transforming solar energy into something else

Non-concentrating solar collectors

surface that is collecting solar energy, mainly used to heat up water, not as effective

Concentrating solar collectors

much large surface, a much smaller surface takes the energy

Benefits of solar energy

cannot be exhausted

there for the people

no emissions/no mining

Limitations of solar energy

whether dependent

nighttime

expensive

dilute

How does the world-wise use of biomass compare to other renewable energy sources?

It is the most used in regard to renewable energy sources

Direct combustion

solid biomass (food waste, animal manure)

Biomass power plant

Gaseous biomass

Methane gas

What are liquid biofuels

transportation fuels that come from plant materials

How are liquid biofuels made/produced?

grow the crops (corn, soybeans, sugarcane, sunflower), and use the plants to create biofuels via combustion

Two common examples of biofuels

ethanol, biodiesel

(they are NOT carbon neutral)

What is carbon neutrality?

the amount of carbon released in the air is equivalent to the amount of carbon absorbed

Liquid biofuels are carbon neutral? T/F

False. machines and fertilizers release CO2

Negative Impacts of Biomass

increases food insecurity

carbon emissions, air pollutants

Water pollution

How does Wind Energy work?

Wind turns the blade, which turns a gear and turns on a generator (does not use steam)

What energy transformation is involved in wind energy?

wind is kinetic, electricity is kinetic

What are the benefits of wind energy?

No emissions

Renewable

Bring the energy source to the people

What are the limitations of wind energy?

not very reliable

unsightly/noisy

pollution that comes from the production of a windmill

Kills wildlife (birds/bats)

Where does Geothermal energy come from?

Core of the Earth (heat from the core heats the rocks, rocks heat the water)

What is one use of the hot water produced in Geothermals?

hot water

heating homes

What is the steam generated for in geotherms?

to produce electricity

What are the main drawbacks of geothermal electricity?

not every place has access

the water used can be heavily polluted, and can pollute drinking water

painting geothermal water is expensive and noisy

How does Hydroelectric Power work and how is it linked to the sun?

Force of flowing water turns the turbine which produces electricity (indirectly tied to the sun due to the rain cycle)

Storage Hydroelectric

using potential energy and storing water behind a dam

highest impact, highest efficiency, most reliable

Pumped-storage hydroelectric

using energy to pump water into a reservoir (water in an upper reservoir has potential energy, transferred naturally to lower reservoir, then pumped back up)

Run-of-River Hydroelectric

Divert a small part of a river and use gravity to turn a turbine

least impactful, least efficient, least reliable

Environmental Impacts of Hydroelectric Power

Habitat/ecosystem

Wildlife (salmon coming back)

Water temp (flowing water is cooler, standalone is hotter)

Flow characteristics

Upstream (losing forests bc of flooding behind dam)

Downstream: rivers/streams drying up

Silt load effects (sediments trapped behind wall instead of going to the coast)

Human populations (people move to dams)

Fuel Cell

miniature power plant that uses hydrogen as a fuel source to produce electricity

Where do fuel cells get hydrogen from?

Water sources

When hydrogen is used In the fuel cell, what is the waste product

water vapor

Where does the hydrogen fuel come from/how is it produced?

Electrolysis - using an electric current through water to split H2 from O

What are the waste products from electrolysis

Oxygen

What’re the obstacles/weaknesses of hydrogen currently?

not much infrastructure, tech isn’t widespread

To extend the life of the concentrated but limited energy sources, conservation is necessary through

using less (driving less, turning off lights, etc)

Increasing conversion efficiency

Why worry about conserving energy when law of thermodynamics?

because energy transformation degrades the concentrated energy from to a less useful form (heat)