Chapter 13 Achieving Energy Sustainability Energy From the

Chapter 13 Achieving Energy Sustainability

Energy From the Moon • Tidal Energy! • Moon’s gravitational pull interacts with Earth’s gravity and rotation to make tides rise and fall. • This kinetic energy is captured and converted into a usable form as water flows through turbines. • Roosevelt Island Tidal Energy (RITE) Project. • Produces 35 Mega-watt hours(MWh) per yr. • Little environmental impact. • Produces way less energy than oil. • Possible supplement in the future.

What is Renewable Energy? Non-renewable: finite: oil, gas, coal, nuclear. Potentially Renewable(can be replenished if used sustainably): wood, biofuel. Non-depletable: does not run out, the amount available tomorrow does not depend on how much we use today.

How Can We Use Less Energy? • Minimize through conservation and efficiency! Energy Conservation: finding ways to use less energy. Government Incentives: tax breaks rebates and incentives, education, taxing fossil fuel use, improving the availability of public transportation. Tiered System: customers pay a low rate for the first increment of electricity they use and pay higher rates as their use goes up.

Increase Efficiency!! Light Bulbs: • Fluorescent bulbs use ¼ as much energy as incandescent (with the same amount of light). • LED (light emitting diode) are more efficient only using 1/6 th as much energy as incandescent lights. Energy Star Appliances: EPA approved appliance that use much less energy.

Benefits of Energy Conservation and Efficiency Peak Demand: the greatest quantity of energy used at any one time. • Reduce peak demand! • Prevents electric companies from building excess generating capacity. • Only about 1/3 of energy consumed in a typical power plant is useable.

Sustainable Design • Community planning: building homes close to places of business. Passive Solar Design: a technique that takes advantage of solar radiation to maintain a comfortable temperature. • Window position. • Double paned windows. • Maximum light input due to window position. • Color of material on roof.

Thermal Inertia: ability of material to retain heat or cold. High thermal inertia materials stay hot one they have been heated and cool when they have been cooled (cement, stones). Low thermal inertia: wood and glass. Change faster. Green Roofs, Using recycled material, Radiant Heating Systems, and solar panels.

Biomass: Energy From the Sun • Renewable source that is most widely used today! • Wood, charcoal, animal products and manure, plant remains, municipal solid waste (MSW), ethanol and biodiesel. • Account for more than 10% of world energy consumption. • Biomass accounts for ½ of renewable energy and about 3. 5% of all energy consumed in the US today.

Modern Carbon: incorporated recently. When burned we return the carbon back to where it came from. • Ends up as a carbon neutral. Fossil Carbon: buried for million of years.

Solid Biomass: Wood, Charcoal, & Manure • Worldwide 2 -3 billion people use wood for heating or cooking. • US: 3 million homes rely on wood. Net Removal: unsustainable practice that leads to deforestation. • Tree removal can be sustainable if time is given for regrowth. • Can open up canopy increasing habitat diversity and photosynthesis.

Charcoal: lighter than wood, 2 x as much energy production per unit weight, less smoke, and does not need to be tended. Dry Animal Manure: used where wood is scarce, reduces microorganisms that spread disease, creates air pollution. Burning biomass fuels produces a variety of air pollutants, including particulate matter, carbon monoxide and nitrogen oxides.

Biofuels: Ethanol and Biodiesel • Liquid, can be substituted for gas and diesel.

Ethanol • Alcohol, same one found in beverages. • Made by converting starches and sugars form plant material into alcohol and carbon dioxide. • 90% comes from corn and corn by-products. • US is the world producer in ethanol production. • We still only make a fraction of what President Bush proposed. • Ethanol and biodiesel only constitute. 6% of our US energy supply

• Brazil uses sugarcane. • Gasohol: 10% ethanol, 90% gas. Produces less particulate pollution. • Flex-fuel vehicles can run on gas or E-85 (85%ethanol 15% gas). Disadvantages: • Not as efficient as gas. • Uses a lot of land to grow the corn. • Uses fossil fuels to harvest the corn. Maybe switchgrass? ?

Biodiesel • Substitute for regular petroleum diesel. • Produced by extracting oil from algae and plants such as soybean and palm. • Mostly soybean or vegetable oil. • More expensive than petroleum diesel. • Solidifies into a gel at low temps. • Carbon neutral, less emissions. • Needs cropland!! Straight Vegetable Oil (SVO): waste product from restaurants.

Kinetic Energy of Water Produces Electricity Hydroelectricity: electricity generated by the kinetic energy of moving water. • 2 nd most common form of renewable energy in the US and the world. • Worldwide 20% of all electricity comes from hydroelectric power. • China is the world’s leading producer of hydroelectricity.

How it Works • A hydroelectric power plant captures kinetic energy of the water moving and uses it to turn a turbine. • Depends on the flow rate, the vertical distance the water falls, or both. • Higher fall, more kinetic energy, faster the flow, the greater the kinetic energy!

Run of the River Systems • Water is retained behind a low damn and runs through a channel before returning to the river. • Little flooding occurs upstream. • Seasonal changes in the river are not disrupted. • Generally small, cannot store during time periods with a lot of water. • Does not produce during dry spells.

Water Impoundment Systems • Storing water in a reservoir behind a dam. • Allows for electricity production on demand. • Rate of flow is determined by the operators. Largest in the US: Grand Coulee Dam in Washington State (6800 MW at peak) World: Three Gorges Dam on the Yangtze River in China (18000 MW, 85 billion kilowatt-hours per year)!

Tidal Systems • Water movement due to gravitational pull of the moon. • Does not have the potential to become a major energy source. • Not a big enough distance between high tide and low tide. • Transmission lines must be built along coastlines which can disrupt ecosystems and marine ecology.

Is Hydroelectricity Sustainable? ? Benefits: • Once built, minimal amount of fossil fuels needed. • Generate large amounts of electricity. • No air pollution, waste products or carbon dioxide emissions. • Less expensive for consumer(5 -11 cents/Kwhour). • Reservoirs can provide recreational and economic opportunities. • Flood control.

Disadvantages • Holds back free flowing rivers. • Reservoir may flood nearby agriculture lands. • Unsuitable for organisms or recreation that depend on free flowing rivers. • Hold more heat and less oxygen. • Parasites and disease become more prevalent in standing water. • Disrupts biodiversity: Some organism’s life cycles depend on the river flow.

Solutions? • Fish ladders. Other Effects • Fossil fuel burning during construction. • Production of cement (5% of global anthropocentric CO 2 emissions) • Methane release from dead plants and animals. • Sediment collection(siltation) at the bottom of the reservoir.

Capturing the Sun’s Energy • Almost limitless! • Varies based on region. • 3 k. Wh of energy per square meter in the Pacific Northwest to almost 7 k. Wh in the southwest.

Passive Solar Heating -Using the sun without the use of active technology. • Positioning windows on south-facing walls. • Covering roofs with dark material to absorb heat. • Building homes into the side of a hill.

Solar Ovens -Concentrates sunlight. • Prevents deforestation. • Do not have to leave home.

Active Solar Energy Technologies • Use technology in harnessing the sun’s energy.

Solar Water Heating Systems • Swimming pools, hot water in businesses and homes. • Liquid is heated by the sun then circulated to a storage tank. • Often used as a back up system.

Photovoltaic System • Capture the sun’s energy as light (not heat) and convert it to electricity. • Semiconductors generate a low-voltage electric current when exposed to direct sunlight. • Converted into higher-voltage alternating current for use in homes or businesses. • 12 -20% efficient in turning sunlight energy into electricity.

• Solar panels. • Most are tied to the electrical grid then bought by the electric company or will give the customer credit toward future electricity use. • “Off the grid” consumers can store energy in batteries and use later. • Some emergency phones and parking meters have replaced others that required energy.

Concentrating Solar Thermal Electricity Generation (CST) • Large scale harnessing of the sun’s energy. • Use lenses or mirrors and tracking systems to focus the sunlight into a small concentrated area. • Heat is used to evaporate water into steam that turns a turbine and generates electricity. • Similar to a thermal power plant except the energy comes from the sun rather than fossil fuels. • Needs a lot of space!

Benefits to Solar • Energy production without air pollution, water pollution or CO 2 emissions. • Produce when needed the most: on hot days when demand it high (air conditioning). • Reduces the need to build more fossil fuel power plants. • Economically feasible.

Disadvantages • Photovoltaic solar panels are expensive to manufacture and install. • Takes a great deal of energy and water to make. • Toxic metals are used and pollution is released into the environment. • Difficult to recycle or dispose of batteries.

Earth’s Internal Heat: Non-depletable Energy Geothermal Energy: comes from radioactive decay deep within the Earth.

Harvesting Geothermal Energy • Hot groundwater can be piped directly into the house. • Groundwater is a renewable resource so it can run out. • In Iceland 20% of their energy is supplied through geothermal techniques. • US uses about 5%. • Not easily accessible. • Hazardous and gases and steam may be emitted from the power plant.

Ground Source Heat Pumps • Uses the high thermal inertia of the ground. • Cycles fluids through pipes buried underground.

Wind Energy: Most Rapidly Growing Source of Energy • Wind is the result of the unequal heating of the Earth’s surface.

Generating Electricity from Wind • A wind turbine converts the kinetic energy of moving air into electricity. • Offshore wind turbines work the best. • Often placed in rural areas away from buildings and population centers. • Must be near electrical transmission lines.

Advantages Non-depletable. Clean. Free. The amount available tomorrow does not depend on how much we use today. • No pollution. • No greenhouse gases. • Can share the land with grazing cattle. • •

Disadvantages • • • Off grid farms have to rely on batteries. Noise. Not aesthetically pleasing. Birds! As many as 40, 000 birds may be killed by wind turbine blades per year.

Hydrogen Fuel Cells Have Many Potential Applications Fuel Cell: reactants are continually added therefore it is never used up. • Electricity is generated with hydrogen gas and oxygen gas. Electrolysis: an electrical current is applied to water and split into hydrogen gas and oxygen.

Is Hydrogen a Viable Energy Alternative? • • Has potential but needs more research. Need a way to obtain hydrogen. Need a way to distribute the hydrogen. Has the possibility of explosion.

Planning for the Future • Renewable energy resources are unlikely to replace fossil fuel. • Wind and solar energy account for far less than 1 percent of the energy produced in the US.

Improving the Electrical Grid • Upgrade existing electrical infrastructure. • 40% of the energy used in the US is to generate electricity. • Outages and overloads cost the US electrical distribution $100 billion per year. • 5 -10% of electricity generated is lost as it is transported along electrical lines.

Smart Grid: efficient, self regulating electricity network that accepts any source of electricity. • Uses computer programs and Internet to tell electricity generators when electricity is needed and electricity users when there is excess capacity on the grid. • Coordinates energy use with energy availability.

Addressing Energy Cost and Storage • Major impediments to widespread use of wind, solar, and tidal energy are cost and limitations of storage. • Incentives. • Will get better as the technology improves.