Global Ozone Project Curriculum

Lesson:Renewable Energy

Rev 10ABrian Carpenter, Jessa Ellenburg and John Birks

Learning Objectives

At the end of this lesson students should be able to:

• Identify Non-Renewable Energy Sources.

• Identify the top five Renewable Energy Sources.

• Identify Pros and Cons for each Renewable Energy Source.

Global Ozone Project Curriculum

Part 1:Introduction to Energy Use

Energy Introduction

• Heat Engine: a device that can convert heat energy to mechanical energy.– Fancy name for a car engine, a power plant, your

refrigerator, air conditioner, etc.

• Efficiency of a heat engine is expressed in terms of the temperature difference between the hot side and the cold side. Efficiency = (Thot – Tcold)/Thot

• Cars are only about 20 to 30% efficient. Coal fired power plants are around 35% efficient.

Electricity Introduction

Generating Electricity– To get electricity, we convert

mechanical energy to electrical energy

– Converting mechanical energy to electricity is done by electromagnetic induction discovered by Michael Faraday in 1831.

Michael Faraday

Electricity

Generating Electricity

• Spinning conductive wires inside a magnetic field causes electrons to move inside the wires, and moving electrons are electricity.

• We can use both renewable and nonrenewable energy sources (fossil fuels) to do this.

Energy Sources

Major Renewable Sources • Solar• Hydropower• Wind• Biomass• Geothermal

Major Non-Renewable Sources• Oil • Coal• Natural gas• Nuclear• Fuelwood

From Energy Sources to Electricity

US vs. Global Energy Use

US Energy Use Global Energy Use

Energy Production by State

Global Ozone Project Curriculum

Part 2:Renewable Energy Technologies

Renewables

Major Renewable Energy Sources • Hydropower• Biomass• Geothermal• Wind• Solar

Active SolarWe utilize two types of Solar Energy:

Active Solar & Passive Solar

Active Solar:Technologies like Solar Panels (Photovoltaics) are used to convert solar energy into electrical energy.

Passive Solar - Heating and Cooling

Passive Solar: Direct use of sun’s heat energy for home heating.

Passive Solar – Water Heating

Another use of passive solar – to heat water for household use.

Solar Potential for the US

Costs of Solar Electricity (Active Solar)

Costs of PV electricity:• Industrial system (500 kilowatt system, about $2.5M).• Sunny day: 15-20 cents/kWhr, 35-55 cents on a

cloudy day.• Home system (2 kilowatt system, about $18,000).• Sunny day: 35 cents/kWhr, 80 cents on a cloudy day.

Compare this with electricity from coal:• Peak cost: 15 cents/kilowatt-hour.• Off-peak cost: 10 cents/kilowatt-hour or less.

Pros and Cons of Active Solar (Solar Panels)Pros:• Solar panels give off no pollution, the only pollution produced as a result of solar panels is the

manufacturing of these devices in factories, transportation of the goods, and installation.• Solar energy produces electricity very quietly.• The ability to harness electricity in remote locations that are not linked to a national grid. • The installation of solar panels in remote locations is usually much more cost effective than laying the

required high voltage wires.• Solar energy can be very efficient in a large area of the globe, and new technologies allow for a more

efficient energy production on overcast/dull days.• Space is not an issue because solar panels can be installed on top of many rooftops.• Solar is cost-effective. Although the initial investment cost of solar cells may be high, once installed, they

provide a free source of electricity, which will pay off over the coming years.• Utilizing solar energy decreases dependence on fossil fuels.

Cons:• The major con of solar energy is the initial cost of solar cells. Currently, prices of highly

efficient solar cells can be above $1000, and some households may need more than one. • Solar energy is only able to generate electricity during daylight hours. • The weather can affect the efficiency of solar cells.• Pollution can affect a solar cell’s efficiency.

Pros and Cons of Passive Solar Heating/CoolingPros:• Renewable. No fuels required.• Non-polluting. Carbon free except for

production and transportation.• Simple, low maintenance.• Hot water provides some storage capacity.• Operating costs are near-zero.• Quiet. Few or no moving parts.• Mature technology.• Good return on investment.• High efficiency.• Can be combined with photovoltaics in

highly efficient cogeneration schemes.

Cons:• Intermittent.• Low energy density.• Does not produce electricity.• Supplemental energy source or storage

required for long sunless stretches.• Expensive compared to conventional water

heaters.• Construction/installation costs can be high.• Hard to compete against very cheap natural

gas.• Some people find them visually unattractive.• Manufacturing processes can create

pollution.• Installers not available everywhere.• Generally not practical to store or sell excess

heat.• Produce low grade energy (heat vs.

electricity).• Dependent on home location and orientation.

Future of Solar PowerWays to improve:1. Concentrators: these are mirrors that

concentrate the sun’s energy to improve efficiency.

2. Hybrid Solar Systems: combine solar with other forms of energy production to make cheaper and more reliable. For example, solar-wind, and solar-hydro.

3. Consider Cost of Pollution: Cost of coal-based electricity is cheaper in part because pollution is not factored into the cost. Cost of pollution from solar (in manufacturing process) would be much less.

Hydropower

Basics:• Form of solar energy, as the

sun drives water evaporation from the ocean and winds carry the moisture overland.

• Largest form of alternative energy used today.

• Industrialized countries have already tapped much of their potential.

• Non-industrialized countries have the most untapped potential.

Hydropower - DamsDams• Height of dam and mass

of water determine useful energy.

• Efficiency is very good to excellent, generally 80 to 90% efficient in converting potential energy to electrical energy.

• Potential Energy = mass*gravity*height

Hydropower Generation

Hydroelectric power production costs less than half of fossil fuel derived electricity (does not include construction costs).

Future of Hydropower

Tidal Power: Propeller Systems

Tidal Power: Wave Systems

Tidal Power:Enclosures

Pros and Cons of Hydropower

Pros:• Very clean.• Cheap.• Flood control (primary reason for dams).• Multiple crops per year possible.

Cons:• Potential is limited globally to about 5 to 10% of energy needs.• Dependability is an issue; prolonged droughts can cut electrical production in half or more.• Dams have drawbacks, including:

Environmental impactsLoss of nutrient flow down riverLoss of sediment flow down riverSedimentation behind the dam limits lifetime of the damFlooding of scenic areas and archaeological sitesEcosystem below the dam is usually changed by having colder, nutrient poor waterAestheticsLoss of wild rivers

Wind Power

Basics• Use dates back

thousands of years in the form of windmills, sailing ships, etc.

• Typical efficiency is about 30%. Maximum theoretical efficiency is thought to be about 60%.

Windmills

US Wind Power Potential

Midwest has more than 90% of US potential

Wind Power Pros/Cons

ProsCost is very competitive, production costs are about 5 cents per kilowatt-hour (coal electricity is around 15 cents). This is down from 7 to 10 cents per kilowatt-hour in 1995 and 15 cents per kilowatt-hour in the 1980's.• In this case subsidies helped to create a viable market.• It is estimated that the costs could be lowered to 3-4 cents per kilowatt-hour as wind

technology improves. Improvements in technology may also open less windy areas up for economically useful and viable wind power.

Cons• Reliability is a key issue, as the wind does not always blow. Requires a storage

mechanism that compensates for reliability.• Recently, aesthetics has become a significant issue.• Killing of birds and bats from high blade tip speeds.• Disruption of natural wind patterns.

Biomass

Basics• Energy from the sun, via photosynthesis in

plants.• This is the same energy we use as food.• This is the same energy that made fossil

fuels; fossil fuels are concentrated over time by the heat and pressure within the Earth.

• The oldest form of energy used by humans: wood fire, a form of biomass.

Biomass

What is biomass?

• Any plant tissue can be used for energy, but the faster the plant grows, the more useful it is.

Biomass

How does it work? How do we convert biomass energy to useful forms of energy?• Direct burning• Gasification• Cofiring• Fermentation

Future of Biomass

• GMO “Energy Crops” - like Poplar and Willow trees which have been genetically engineered and bred for rapid growth

• Algae - also grows rapidly• Biodiesel - Canola and Sorghum, etc.• Cellulosic Ethanol

Developing ideas

Biomass Pros and ConsPros:• Truly a renewable fuel• Widely available• Generally low cost inputs• Abundant supply• Can be domestically produced

for energy independence• Low carbon, cleaner than

fossil fuels• Can convert waste into energy,

helping to deal with waste

Cons:• Energy intensive to produce• Land utilization can be considerable • Requires water to grow• Not totally clean when burned (NOx, soot, ash,

CO, CO2)• May compete directly with food production (e.g.

corn, soy)• Some fuels are seasonal• Energy required to transport• Overall process can be expensive• Some methane and CO2 are emitted during

production• Not easily scalable

Geothermal Power

Geothermal Electricity

Geothermal in the Home

Geothermal Potential in the US

Future of Geothermal

Ocean Thermal Energy Conversion (OTEC):• This is a special case of geothermal energy, as the source of the energy is

the sun, warming the surface waters of the ocean.• Uses the temperature difference between cooler deep and warmer shallow

or surface ocean waters to run a heat engine and produce useful work, usually in the form of electricity.

• The cold water typically comes from about 1000 meters.

Attractions of OTEC are:• Steady source of energy (all day, all year).• Potential large in warm areas (Florida, Hawaii) requiring air conditioning.• Could use this energy to create hydrogen gas from seawater.• Could be used to desalinize water.• Mariculture (seafood farming)

Geothermal Pros and ConsPros:• Almost entirely emission free.• The process can scrub out sulfur that might

have otherwise been released.• No fuel required (no mining or

transportation).• Not subject to the same fluctuations as

solar or wind.• Smallest land footprint of any major power

source.• Virtually limitless supply.• Inherently simple and reliable.• Can provide base load or peak power.• Already cost competitive in some areas.• Could be built underground.• New technologies show promise to utilize

lower temperatures.

Cons:• Prime sites are very location-specific.• Prime sites are often far from

population centers.• Losses due to long distance

transmission of electricity.• Water usage.• Sulfur dioxide and silica emissions.• High construction costs.• Drilling into heated rock is very

difficult.• Minimum temperature of 350F+

generally required.

Emerging Technologies

There are many interesting emerging renewable technologies. A few examples are:Soccer Ball ChargerSpray-on Solar PanelsGreen Gasoline

What will you come up with??