1. Energy
and the
Environment
Renewable Resources and Alternative Energy

2. Energy efficiency calculation:
energy efficiency (in %) = energy in/energy out X 100
Ex. light bulb efficiency = proportion of electrical energy that reaches the bulb and is converted into light energy rather than into heat
Most of our devices are fairly inefficient
More than 40 % of all commercial energy used in the United States is wasted
Most of it is lost from inefficient fuel-wasting vehicles (internal combustion engines), furnaces, and appliances and from leaky, poorly insulated buildings

3. Energy Efficiency of Common Conversion Devices
Incandescent light bulb 5%
Fluorescent light bulb
22%
Internal combustion engine (gasoline)
10%
Human body
20%–25%
Steam turbine
45%
Fuel cell
60%

4. Important aspect of sustainability
Renewable energy -- energy from sources that are constantly being regenerated or replenished.
Important aspect of sustainability

5. Renewables
Major Renewable Energy Sources
Hydropower
Biomass
Geothermal
Wind
Solar

7. Active Solar & Passive Solar
Solar Energy:
We utilize two types
Active Solar & Passive Solar
Active Solar:
Technologies like solar panels (photovoltaic cells) are used to convert solar energy into electrical energy.

8. Active Solar Heating -- energy from the sun can be gathered by collectors and used to heat water or to heat a building
Solar collectors, usually mounted on a roof to capture the sun’s energy

9. Active Solar Energy
In a solar water heating system, a liquid is pumped through solar collectors.
The heated liquid flows through a heat exchanger that transfers the energy to water, which is used in a household.

10. Photovoltaic cells
Solar cells were invented more than 120 years ago, and now they are used to power everything from calculators to space stations.
Sunlight falls on a semiconductor, causing it to release electrons.
The electrons flow through a circuit that is completed when another semiconductor in the solar cell absorbs electrons and passes them on to the first semiconductor.

11. Photovoltaic cells or solar cells convert the sun’s energy into electricity
no moving parts, run on nonpolluting power from the sun
So why don’t solar cells meet all of our energy needs?
produces a very small electrical current.
So meeting the electricity needs of a small city would require
covering hundreds of acres with solar panels. Solar cells also
require extended periods of sunshine to produce electricity.
This energy is stored in batteries, which supply electricity
when the sun is not shining.
Solar cells have great potential for
use in developing countries, where
energy consumption is
minimal and electricity distribution
networks are limited.

12. Solar Panel Pros:
gives off no pollution, the only pollution produced is the manufacturing of the devices in factories, transportation of the goods, and installation.
produces electricity very quietly.
harness electricity in remote locations.
space saving, can be installed on top of many rooftops.
cost-effective, initial investment cost may be high, once installed, they provide a free source of electricity, which will pay off over the coming years.
decreases dependence on fossil fuels.

13. Solar Panel Cons: initial cost
only able to generate electricity during daylight hours.
weather can affect the efficiency of solar cells.
pollution can affect efficiency.

14. Solar Potential for the US
Solar also has a large potential for growth - total incoming solar radiation equates to about 3,000 times more solar energy than total energy used worldwide.

15. Passive Solar:
uses the sun’s energy to heat something directly.

16. In passive solar building design, windows, walls, and floors are made to:
collect, store, and distribute solar energy in the form of heat in the winter
must be well insulated with thick walls and floors in order to prevent heat loss
reject solar heat in the summer
Doesn't involve the use of mechanical and electrical devices.
Key  take advantage of the local climate.
Consider: window placement and size, thermal insulation, thermal mass, and shading.

17. Passive solar buildings are oriented according to the yearly movement of the sun.
In summer, the sun’s path is high in the sky and the overhang of the roof shades the building and keeps it cool.
In winter, the sun’s path is lower in the sky, so sunlight shines into the home and warms it.

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

19. Passive Solar Pros: 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 photovoltaic cells in highly efficient cogeneration schemes.

20. Passive Solar 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.
Visually unattractive to some.
Manufacturing processes can create pollution.
Produce low grade energy (heat vs. electricity).
Dependent on home location and orientation.

21. Hydropower Largest form of alternative energy used
About 20 % of the world’s electricity is produced by hydropower.
The countries that lead the world in hydroelectric energy are China, Canada, Brazil, United States, Russia
HIGHEST DAM IN THE UNITED STATES
Oroville on the Feather River in California
770 feet
LARGEST HYDRO PROJECT IN THE UNITED STATES
Grand Coulee on the Columbia River in Washington
6180 MW

22. Hydroelectricity—Power from Moving Water
Energy from the sun causes water to evaporate, condense in the atmosphere, and fall back to the Earth’s surface as rain.
Gravity causes water to flow downwards -- this downward motion of water contains kinetic energy that can be converted into mechanical energy, and then can be converted into electrical energy at hydro-electric power stations

23. The energy of this water is evident shown in the spillway.
Large hydroelectric power plants have a dam that is built across a river to hold back a reservoir of water.
The water in the reservoir is released to turn a turbine, which generates electricity.
The energy of this water is evident shown in the spillway.
Three Gorges Dam

24. How Hydropower Works
Hydroelectric dams convert the potential energy, or stored energy, of a reservoir into the kinetic energy, or moving energy, of a spinning turbine. The movement of the turbine is then used to generate electricity.

25. Large dam construction
• Industrialized (developed)countries have already tapped much of their potential.
• Non-industrialized (developing) countries have the most untapped potential such as Brazil, India, and China.
A modern trend is micro-hydropower, which is electricity produced in a small stream without having to build a big dam.
The turbine may even float in the water, not blocking the river at all.
Micro-hydropower is much cheaper than large hydroelectric dam projects, and it permits energy to be generated from small streams in remote areas.

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

27. Future of Hydropower Tidal Power: Wave Systems
Tidal Power: Propeller Systems
Tidal Power: Enclosures

28. Hydropower Pros:
• very clean, does not release air pollutants that cause acid precipitation
• inexpensive to operate
• provides other benefits such as flood control and water for drinking, agriculture, industry, and recreation

29. Hydropower Cons:
Provides about 5 to 10% of energy needs
Expensive to build
Dependability; prolonged droughts can cut electrical production in half or more.
Ecosystem above/below the dam is changed
Blocks migratory fish
Destroys habitats
When land behind a dam is flooded, people are displaced.
Dam failure —if a dam bursts, people living in areas below the dam can be killed.
As a river slows down, the river deposits some of the sediment it carries. This
fertile sediment builds up behind a dam instead of enriching the
land farther down the river. As a result, farmland below a dam can become less productive (loss of nutrients).
Recent research has also shown that the decay of plant matter trapped in reservoirs can release large amounts of greenhouse gases
Loss of aesthetic value

30. Wind Power
Use dates back thousands of years in the form of windmills, sailing ships, etc.

31. Wind Power—Cheap and Abundant
Energy from the sun warms the Earth’s surface unevenly, which causes air masses to flow in the atmosphere.
We experience the movement of these air masses as wind.
Wind power, which converts the movement of wind into electric energy, is the fastest growing energy source in the world.

32. Technology development – more efficiently capturing wind (blade types)
Simple technology
Wind energy turns the fan blades, which turn the turbine to generate electricity.
Technology development –
more efficiently capturing wind (blade types)
making towers that can work in high winds
To optimize output, it is best to position wind turbines in areas of constant wind, yet these areas typically have high winds and can damage the windmills.
Wind turns the blades and gears are used spin the generator.

33. In California, large wind farms supply electricity to 280,000 homes.
In windy rural areas, small wind farms with 20 or fewer turbines are also becoming common.
Because wind turbines take up little space, some farmers can add wind turbines to their land and still use the land for other purposes.
Farmers can then sell the electricity they generate to the local utility.
Pasadena, CA

34. Scientists estimate that the windiest spots on Earth could generate
more than ten times the energy used worldwide.
One problem of wind energy is transporting electricity from rural areas where it is generated to urban centers where it is needed.
In the future, the electricity may be used on the wind farm to produce hydrogen from water. The hydrogen could then be trucked or piped to cities for use as a fuel.

35. Midwest has more than 90% of US potential Montana, Wyoming, Colorado, New Mexico, North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas, Iowa and Minnesota

36. Wind Power Pros Wind Power Cons
Cost is very competitive, production costs are about 5 cents per kilowatt-hour (coal electricity is around 15 cents).
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.
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.

37. Atlantic City, NJ

39. 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.
In the developed world, biomass that was once thought of as waste is being used for energy.

40. What is biomass?
Energy from plants and plant-derived materials
Any plant tissue can be used for energy, but the faster the plant grows, the more useful it is.

41. Biomass—Power from Living Things
Plant material, manure, and any other organic matter that is used as an energy source
Fossil fuels are organic and can be thought of as biomass energy sources, but fossil fuels are nonrenewable.
Renewable biomass fuels, such as wood and dung, are major sources of energy in developing countries.
Although wood is a renewable resource, if trees are cut down faster than they grow, the resulting habitat loss, deforestation, and soil erosion can be severe.
In addition, harmful air pollution may result from burning wood and dung.

43. The consumption of wood as an energy source has increased by nearly 80 percent since 1960.
In developing countries such as Nepal, Burma, Guatemala, Congo (DRC), and Kenya, the use of fuelwood places an enormous burden on local environments.
More than half of all wood cut in the world is used as fuel for heating and cooking

44. Methane can be burned to generate heat or electricity.
In China, more than 6 million households use biogas digesters to ferment manure and produce gas used for heating and cooking.
In 2002, Britain’s first dung-fired power station started to produce electricity.
This power station uses the methane given off by cow manure as fuel.
Similarly, some landfills in the United States generate electricity
by using the methane from the decomposition of trash.

45. Biomass
How does it work? How do we convert biomass energy to useful forms of energy?
• Direct burning
• Gasification
• Co-firing
• Fermentation

46. Methods to convert biomass to energy
Direct burning: Plant material is chipped, dried, and then burned to boil water, make steam, and then electricity. This is a relatively inefficient technology and the most polluting method of energy from biomass.
Gasification: The conversion of biomass into a gas and carbon powder. Process begins with pyrolysis. Biomass is combined with hot sand (800°C). This reduces biomass to gases and carbon powder.
Cofiring: The use of biomass in combination with coal. Biomass cheaper than coal, so cofiring is cheaper than burning coal alone. It also produces less sulfur oxide pollution. It is easy to adapt current systems to cofiring.
Fermentation: The production of alcohol (ethanol mainly) from sugars in biomass. The alcohol can be burned alone, or mixed with gasoline. Mixtures can range from 10% ethanol (often used to reduce pollution) to 100% ethanol. Ethanol is about as expensive as gasoline currently (although comparisons are hard to make due to the many subsidies for both). The net energy yield from ethanol is low.

47. Alcohol liquid fuels can also be derived from biomass.
For example, ethanol, an alcohol, can be made by fermenting fruit or agricultural waste.
In the United States, corn is a major source of
ethanol.
Cars and trucks can run on ethanol or gasohol, a blend of gasoline and ethanol.
Gasohol produces less air pollution than fossil fuels do. For this reason, some U.S. states require the use of gasohol in vehicles as a way to reduce air pollution.
Ethanol as a source of energy must compete with food production, and will have less dependability from year to year as climate change affects crops.

48. Currently we get less than 1% of our energy in industrialized countries from biomass.
While biomass is compelling, as our population continues to grow the competition for arable land and water needed for food production is going to make a number of biomass options unsuitable.
However, there are a number of these options that utilize forestry, agricultural, and even industrial waste (e.g. paper), as well as trash found in landfills and recycled nutrients from waste water treatment facilities.
Not only are these more efficient input sources, but in many cases using them will also help to address waste disposal issue.

49. Future of Biomass Developing ideas
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

50. Biomass Pros and Cons Pros: Cons: 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.

51. Geothermal Energy—Power from the Earth
Uses steam from wells (geothermal reservoirs) that reach deep in the Earth. These reservoirs are usually found along the earth's major plate boundaries where volcanoes and earthquakes occur most frequently.
Geothermal power plants pump heated water or steam from rock formations and use the water or steam to power a turbine that generates electricity.
Usually the water is returned
to the Earth’s crust
where it can be heated
and used again.

52. Geothermal power plants generate electricity using the following steps:
1) steam rises through a well;
2) steam drives turbines, which generate electricity;
3) leftover liquid water is pumped back into the hot rock.

53. Geothermal energy is clean energy because no fuel is burned, so there are no harmful pollutants released into the environment.
There are three types of geothermal energy used to make electricity:
Hydrothermal: Uses steam and hot water. This is the most widely used process. In industrial applications, the steam is pumped from wells directly from the reservoir to a giant turbine. The turbine spins a magnet which generates the electricity.
Geopressurized: Uses hot water (around 350°F) and hydraulic turbines
Petrothermal: Uses dry hot rocks requiring water injections to make steam.

54. The United States is the world’s largest producer of geothermal energy.
The world’s largest geothermal power plant is in Geysers, California,
which produces electricity for about 1.7 million households.
Other countries that produce geothermal energy include the Philippines, Iceland, Japan, Mexico, Italy, and New Zealand.
Iceland, already generates more than 25 percent of its energy from geothermal.
Although geothermal energy is considered a renewable resource, the water in geothermal formations must be managed carefully so that it is not depleted.
A panoramic view of the Geysers geothermal power plant in Geysers, Calif. The site, located above Santa Rosa, is the largest geothermal development in the world.

55. Geothermal energy can be used for heating homes.
Cool water is sent into the ground and is warmed by geothermal heat.
Geothermal resources vary from location to location, but as new technologies emerge that are capable of utilizing lower temperatures, geothermal power will become more widespread.

56. Geothermal Heat Pumps: Energy for Homes
Because the temperature of the ground is nearly constant year-round, a
geothermal heat pump uses stable underground temperatures to warm and cool homes.
A heat pump is simply a loop of piping that circulates a fluid underground.
In warm summer months, the ground is cooler than the air, and the fluid is used to cool a home.
In the winter, the ground is warmer than the air, and the fluid is used to warm the home.

57. Geothermal Power Hot Springs in Iceland
Japanese Snow monkeys enjoy the hot spring in their snow-covered surroundings

58. Geothermal Potential in the US

59. Ocean Thermal Energy Conversion
In the tropics, the temperature difference between the
surface of the ocean, which is warmed by solar energy,
and deep ocean waters can be as much as 24°C (43°F).
An experimental power station off the shores of Hawaii
uses this temperature difference to generate electricity.
This technology is called Ocean Thermal Energy Conversion
In this system, warm surface water is used to boil sea water.
This is possible because water boils at low temperatures when it is at low pressure in a vacuum chamber.
The boiling water turns into steam, which spins a turbine.
The turbine runs an electric generator.
Cold water from the deep ocean cools the steam, turning
the steam into water that can be used again.

60. One problem with OTEC is
that the power needed to pump cold water up from
the deep ocean uses about one-third of the electricity
the plant produces. Therefore, the OTEC plants are inefficient.
The environmental effects of pumping large amounts of cold water to the surface are also unknown.

61. Geothermal Pros and Cons
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.

62. Tidal power is a form of hydropower.
Tides are the movement of water in the oceans and seas caused by gravitational attraction between the sun, Earth, and moon.
The tides, which happen twice each day, are marked by the rising and falling of the sea level.

63. The energy of the tides was used nearly a thousand years ago to power mills in France and Britain.
Today, tidal power is used to generate electricity in countries such as France, Russia, and Canada.
Tidal power has a potential equal to only 1 to 2 percent of current global energy use, however it is useful in certain coastal settings, and is very cheap to produce and maintain.
The tidal mill at Carew, England
Tidal mill at Olhão, Portugal

64. A tidal power plant works much like a hydroelectric dam.
As the tide rises, water flows behind a dam; when the sea level falls, the water is trapped behind the dam.
When the water in the reservoir is released, it turns a turbine that generates electricity.

65. Tidal Power Cons:
Tides cycle every 12.5 hours, daily peak production/slack times vary.  this causes a mismatch in supply and demand, as industrial demand is high during the day and low at night.
Tides vary seasonally and monthly as well.
The tidal range is about 2 feet to about 20 feet, the higher the tide, the more useful the energy.
Tidal dams produce about 1/3rd the power of river dams.
Ship traffic is hindered
Ecological damage to marine ecosystems and migrating fish species.
The cost of building and maintaining a tidal power plant is high,
and there are few locations that are suitable.
Tidal Power Pros:
Inexpensive, less than 1/5th the cost of fossil fuel power (not including construction costs).
Renewable
Nonpolluting

66. Hydrogen—A Future Fuel Source?
Hydrogen, the most abundant element in the universe, can be burned as a fuel.
Hydrogen is found in every molecule of living things, and it is also found in water.
Hydrogen does not contain carbon, so it does not release pollutants associated with burning fossil fuels and biomass.
When hydrogen is burned, it combines with oxygen to produce water vapor, a harmless byproduct, and small amounts of nitrogen oxides.
Hydrogen gas (H2) can be produced by using electricity to split molecules of water (H2O).

67. The Challenge of Hydrogen Fuel
Hydrogen takes a lot of energy to produce. If this energy comes from burning fossil fuels, generating hydrogen would be expensive and polluting.
One alternative is to use electricity from solar cells or wind power to split water molecules to produce hydrogen.
Hydrogen could then be stored in pressurized tanks and transported in gas pipelines.
Or hydrogen might not be stored at all—
it might be used as it is produced, in fuel cells.

68. Fuel Cells
Like a battery, fuel cells produce electricity chemically, by combining hydrogen fuel with oxygen from the air.
When hydrogen and oxygen are combined, electrical energy is
produced and water is the only byproduct.

69. The space shuttles have used fuel cells for years.
One of the three fuel cells that make up the generating system that provides electrical power to the space shuttle orbiter. The unit is a little more than a foot high and weighs approximately 200 pounds.

70. Cogeneration
One way to use fuel more efficiently is cogeneration = the production of two useful forms of energy from the same fuel source.
For example, the waste heat from an industrial furnace can power a steam turbine that produces electricity. The industry may use the electricity or sell it to a utility company.
The synthetic methane gas from the anaerobic digester is burned in a gas turbine that transmits a mechanical force that is used to create electricity. At the same time, the turbine produces exhaust gases that heat water to make process steam.

71. Energy Conservation = saving energy.
It can occur in many ways, including using energy-efficient devices and wasting less energy.
Conservation in…
Cities and Towns
Your home
Your daily life

72. Ways to Save Energy Around the House

73. Hybrid cars
Hybrid cars use a small, efficient gasoline engine most of the time, but they also use an electric motor when extra power is needed, such as while accelerating.
Hybrid cars feature many other efficient technologies.
Convert some braking energy into electricity
and it is stored in the battery.
To save fuel, hybrid cars sometimes shut off the gasoline engine, such as when the car is stopped at a red light.
Designed to be aerodynamic, and they are made of lightweight materials so that they need less energy to accelerate.
Cost less to refuel, and they produce less harmful emissions.