Chapter 13 Achieving Energy Sustainability

What is renewable energy? Renewable energy can be rapidly regenerated, and some can never be depleted, no matter how much of them we use. Renewable energy cheaper if we eliminate Inequitable subsidies Inaccurate prices Artificially low pricing of nonrenewable energy

How can we use less energy? Energy conservation- finding ways to use less energy. For example, lowering your thermostat during the winter or driving fewer miles.

How can we use less energy? Energy efficiency- getting the same result from using a smaller amount of energy.

We Can Save Money and Energy in Existing Buildings Conduct an energy survey Insulate and plug leaks Use energy-efficient windows Stop other heating and cooling losses Heat houses more efficiently Heat water more efficiently Use energy-efficient appliances Use energy-efficient lighting

Fig , p. 407

Why Are We Still Wasting So Much Energy? Energy remains artificially cheap Government subsidies Tax breaks Prices don’t include true cost Few large and long-lasting incentives Tax breaks Rebates Low-interest loans

Sustainable Design: Rocky Mountain Institute in Snowmass, Colorado Fig. 16-1, p. 397 Research and consulting on energy, energy efficiency, and renewable energy No conventional heating system Heating bills: <$50/year Amory Lovins, energy analyst

Passive Solar Energy Using passive solar energy can lower your electricity bill without the need for pumps or other mechanical devices. Building the house with windows along a south- facing wall which allows the Sun’s rays to warm the house would be an example.

Passive Solar Home in Colorado Fig , p. 410 Technologies available Open windows when cooler outside Use fans Superinsulation and high-efficiency windows Overhangs or awnings on windows Light-colored roof Geothermal pumps

A Green Roof in Chicago Fig. 16-8, p. 405 Green architecture Living or green roofs Superinsulation U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED)

Biomass is energy from the Sun The Sun is the ultimate source of almost all types of energy

Modern Carbon vs. Fossil Carbon Many people are confused how burning biomass such as wood is better then burning coal. “FAST CARBON” The carbon found in biomass was in the atmosphere as carbon dioxide, taken in by the tree, and by burning it we put it back into the atmosphere “SLOW CARBON” OR “CARBON SINK/RESERVOIR” Burning coal is carbon that has been buried for millions of years and was out of circulation until we began to use it. This results in a rapid increase in the concentration of carbon dioxide in the atmosphere.

Case Study: Is Biodiesel the Answer? Biodiesel production from vegetable oil from various sources 95% produced by the European Union Subsidies promote rapid growth in United States

Case Study: Is Ethanol the Answer? Ethanol from plants and plant wastes Brazil produces ethanol from sugarcane Environmental consequences United States: ethanol from corn Low net energy yield Reduce the need for oil imports? Harm food supply Air pollution and climate change?

Case Study: Is Ethanol the Answer? Cellulosic ethanol: alternative to corn ethanol Switchgrass Crop residues Municipal wastes World Ethanol Production

Case Study: Getting Gasoline and Diesel Fuel from Algae and Bacteria Algae remove CO 2 and convert it to oil Not compete for cropland = not affect food prices Wastewater/sewage treatment plants Could transfer CO 2 from power plants Algae challenges 1. Need to lower costs 2. Open ponds vs. bioreactors 3. Affordable ways of extracting oil 4. Scaling to large production

Case Study: Getting Gasoline and Diesel Fuel from Algae and Bacteria Bacteria: synthetic biology Convert sugarcane juice to biodiesel Need large regions growing sugarcane Producing fuels from algae and bacteria can be done almost anywhere

The kinetic energy of water can generate electricity Hydroelectricity - electricity generated by the kinetic energy of moving water. This is the second most common form of renewable energy in the world.

Types of hydroelectric power systems Run-of-the-river systems- water is held behind a dam and runs through a channel before returning to the river. Pros: relatively little flooding occurs upstream, seasonal changes in river flow are not disrupted Cons: small, energy generated depends on natural water flow (can be intermittent) Chief Joseph Dam near Bridgeport, Washington, USA, is a major run-of-the- river station without a sizeable reservoir.

Types of hydroelectric power systems Water impoundment- water is stored behind a dam and the gates of the dam are opened and closed controlling the flow of water. Most common method of hydroelectricity generation Allows for generation on demand, flow controlled by gates Largest in the US: Grand Coulee Dam (WA) Larges in the world: Three Gorges Dam (China- Yangtze River)

Fig , p. 415

Tides and Waves Can Be Used to Produce Electricity AdvantagesDisadvantages RenewableFew suitable sites NonpollutingHigh costs Equipment damaged by storms and corrosion Low net energy

Types of hydroelectric power systems Tidal systems- the movement of water is driven by the gravitational pull of the Moon. Micro-hydropower- 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. much cheaper than large hydroelectric projects permits energy to be generated from small streams in remote areas

Ocean Thermal Energy Conservation In the tropics, the temperature difference between the surface of the ocean and the deep ocean waters can be as much as 24ºC (43ºF). Ocean thermal energy conservation (OTEC) is the use of temperature differences in ocean water to produce electricity. The United States and Japan have experimented with OTEC power, but so far, no project has been able to generate electricity cost effective. OTEC plants are inefficient because about one-third of the electricity the plant produces is used to pump cold water up from the deep ocean. The environmental effects of pumping large amounts of cold water to the surface are also unknown.

Ocean Thermal Energy Conservation An OTEC plant produces energy using the following steps 1.Warm surface water is boiled in a vacuum chamber under low pressure. 2.This produces a steam that drives a turbine to generate electricity. 3.Cold deep-ocean water will condense the steam. 4.The steam turns into water that can be used again.

OTEC is Reality, Not Science Fiction It’s Official! Lockheed Martin Signs Contract for World’s Largest OTEC Plant Lockheed Martin and Beijing-based Reignwood Group signed a contract in 2013 to begin design of a 10- megawatt OTEC power plant, the largest OTEC project to date.Reignwood Groupto begin designOTEC

Solutions: Passive and Active Solar Heating for a Home Fig , p. 409

Trade-Offs: Passive or Active Solar Heating Fig , p. 411 U.S. Availability of Direct Solar Energy

Trade-Offs: Solar Energy for High Temperature Heat and Electricity Fig , p. 412 Solutions: Solar Cooker in India

Rooftop Solar Hot Water on Apartment Buildings in Kunming, China Fig , p. 410

Solutions: Solar Cells on Rooftop and for Many Purposes Fig , p. 413 Photovoltaic (PV) cells (solar cells) Convert solar energy to electric energy Sunlight hits cells and releases electrons into wires

Solar Cell Array in Niger, West Africa Fig , p. 413

Solar-Cell Power Plant in Arizona Fig , p. 414 Global Production of Solar Electricity This solar-cell power plant in the U.S. state of Arizona near the city of Springerville has been in operation since 2000 and is the world’s largest solar-cell power plant. Analysis shows that the plant, which is connected to the area’s electrical grid, paid back the energy needed to build it in less than 3 years.

Trade-Offs: Solar Cells Fig , p. 414 Key problems High cost of producing electricity Need to be located in sunny desert areas Fossil fuels used in production Solar cells contain toxic materials Will the cost drop with Mass production New designs Government subsidies and tax breaks

The Sun’s energy can be captured directly CST systems are large-scale arrays that use lenses and mirrors to concentrate the Sun’s energy onto a “power tower” to heat water to make steam to turn a turbine

Solar Thermal Power in California Desert Fig , p. 411 Solar thermal systems Central receiver system Collect sunlight to boil water, generate electricity 1% of world deserts could supply all the world’s electricity Require large amounts of water – could limit Wet cooling Dry cooling Low net energy yields

Earth’s internal heat produces geothermal energy Geothermal energy- using the heat from natural radioactive decay of elements deep within Earth as well as heat coming from Earth. Geothermal heat pump system Energy efficient and reliable Environmentally clean Cost effective to heat or cool a space uses stable underground temperatures to warm and cool homes because the temperature of the ground is nearly constant year-round

Geothermal Power Plants—Getting Energy from the Earth’s Internal Heat Hydrothermal reservoirs U.S. is the world’s largest producer Hot, dry rock Geothermal energy problems High cost of tapping hydrothermal reservoirs Dry- or wet-steam geothermal reservoirs could be depleted Could create earthquakes

Geothermal Sites in the United States Figure 26, Supplement 8 Geothermal Sites Worldwide

Geothermal Power Plant in Iceland Fig , p. 425

Wind energy is the most rapidly growing source of electricity Wind energy- using a wind turbine to convert kinetic energy into electrical energy. Indirect form of solar energy

Solutions: Wind Turbine and Wind Farms on Land and Offshore Fig , p. 417 Interconnected arrays of tens to hundreds of turbines, called wind farms or wind parks, can be located on land (middle) or offshore (right). The land beneath these turbines can still be used to grow crops or to raise cattle.

Using Wind to Produce Electricity Is an Important Step toward Sustainability Countries with the highest total installed wind power capacity Germany United States Spain India Denmark Wind Power in the United States “Saudi Arabia of wind power” North Dakota South Dakota Kansas Texas

United States Wind Power Potential Figure 24, Supplement 8

Trade-Offs: Wind Power Fig , p. 418 Winds die down; need back-up energy Storage of wind energy “Not in my backyard ” Kills migratory birds Windy areas may be sparsely populated – need to develop grid system to transfer electricity

Hydrogen fuel cells have many potential applications Fuel cell- a device that operates like a common battery where electricity is generated by a reaction between two chemicals. A fuel cell takes in hydrogen gas and separates the hydrogen atoms’ electrons from their protons. The electrons flow through wires to provide electricity, while the protons pass through a membrane and combine with oxygen gas to form water vapor.

Trade-Offs: Hydrogen, Advantages and Disadvantages Fig , p. 428 Chemically locked in water and organic compounds = net negative energy yield Expensive fuel cells are the best way to use hydrogen CO 2 levels dependent on method of hydrogen production

Science Focus: The Quest to Make Hydrogen Workable Bacteria and algae can produce hydrogen through biodegrading organic material Use electricity from renewable energy sources to produce hydrogen Storage options for hydrogen Larger fuel cells – fuel-cell stacks

Conservation & Efficiency in Transportation Corporate average fuel standards (CAFE) standards Fuel economy standards lower in the U.S. countries Fuel-efficient cars are on the market Hidden prices in gasoline: $12/gallon Car manufacturers and oil companies lobby to prevent laws to raise fuel taxes

More Energy-Efficient Vehicles Are on the Way Superefficient and ultralight cars Gasoline-electric hybrid car Plug-in hybrid electric vehicle Energy-efficient diesel car Electric vehicle with a fuel cell Car Energy Source CO 2 ContentEfficiency CO 2 Emissions Honda Natural Gas 14.4 g/MJ 0.32 km/MJ 45.0 g/km CNG Honda Nat Gas g/MJ 0.35 km/MJ 41.1 g/km FCX Fuel Cell Toyota Oil 19.9 g/MJ 0.56 km/MJ 35.8 g/km Prius Tesla Nat Gas g/MJ 1.14 km/MJ 12.6 g/km Roadster Electric Alternative Energy Cars

Hybrid Cars Hybrid cars use small, efficient gasoline engines most of the time, but they also use electric motors when extra power is needed, such as while accelerating. Hybrid cars feature many efficient technologies. They convert some energy of braking into electricity and store this energy in the battery. The gasoline engine is sometimes shut off to save fuel, such as when the car is stopped at a red light. They are aerodynamic in design and need less energy to accelerate.

Solutions: A Hybrid-Gasoline-Electric Engine Car and a Plug-in Hybrid Car Fig. 16-6, p. 403 Battery issues Storage capacity Overheating Flammability Cost

Tesla Motors Tesla Motors was started in Palo Alta, CA in Their first product was the Tesla Roadster, a high performance electric sports car, released in 2008 ($109K). TM released a family sedan, the Model S, in 2012 ($52K). They released an SUV, the Model X, in 2014 ($60K). A smaller sedan & SUV will be released in 2015 & 2016 for around $30K. Their lithium ion batteries have a 100,000 mile life and can be recycled once they no longer hold a charge. Their batteries can also be recharged with a solar cell ($500) that can generate 50 miles worth of electricity a day.

Benefits of Conservation and Efficiency Variable price structure- utility customers can pay less to use energy when demand is lowest and more during peak demand. Smart grid Ultra-high-voltage Super-efficient transmission lines Digitally controlled Responds to local changes in demand and supply Two-way flow of energy and information Smart meters show consumers how much energy each appliance uses U.S cost -- $200-$800 billion; save $100 billion/year

Utilities Can Benefit From Conservation and Efficiency Many energy companies have an extra backup source of energy available to meet the peak demand, the greatest quantity of energy used at any one time. Compressed Air Energy Storage (CAES) facility Located in McIntosh, Ala. Owned by PowerSouth Energy Cooperative Declared commercial in 1991 The other CAES unit is located in Huntorf, Germany. The unit captures off-peak energy at night, when utility system demand and costs are lowest. Compressors force air into an underground storage reservoir at high pressure. PowerSouth uses the stored energy during intermediate and peak energy demand periods to generate electricity. Produces enough electricity to power approximately 110,000 homes. Burns 1/3 of the natural gas per Kwh of output compared to a conventional combustion turbine. urning_compressed_air.mp4