Chapter 13 Achieving Energy Sustainability

Energy From the Moon! Twice a day, the tides change due to the moon’s gravitational pull interacting with Earth’s gravity. The kinetic energy in the moving water turns underwater turbines that generate electricity.

Renewable Energy Renewable energy resources are those resources that we consider potentially renewable as well as non-depletable energy resources. Biomass energy resources are potentially renewable as long as we don’t consume them more quickly than they can be replenished. Solar, wind, geothermal, hydroelectric and tidal energy are nondepletable.

Renewable and Nonrenewable Energy Resources

Even renewable resources have limits! Renewable energy resources provide only about 13% of energy worldwide. Most of that is in the form of Biomass. Overharvesting of wood leads to deforestation and degradation of the land. In the US, only 7% of our total energy is renewable and comes from biomass and hydroelectricity. Turbines kill millions of fish. Solar panels require heavy metals and a great deal of water.

How can we use less energy? Energy Conservation – Not using certain appliances – Using more efficient appliances – Use fluorescent light bulbs – Reduce peak demand – Use energy star appliances – Increase our energy efficiency by losing less energy to heat energy when there is an energy conversion(sustainable home designs)

Biomass is energy from the Sun Biomass energy resources include wood, charcoal, animal products and manure, plant remains, and municipal solid-waste, liquid fuel such as ethanol and biodiesel. Biomass- accounts for more than one-half of the renewable energy and approx.3.5% of all the energy consumed in the US.

Modern Carbon vs. Fossil Carbon Using biomass is carbon neutral. The amount of CO2 released during burning is replaced by the amount reabsorbed by new vegetation planted in the same area. So there should not be any net increase in atmospheric CO2. If there is deforestation though, there will be an increase in CO2. Burning biomass releases particulates, CO, and NOs into the air which causes photochemical smog.

Solid Biomass Wood: Removing more timber than is replaced by growth or net removal of forest is an unsustainable practice that leads to deforestation. This combined with burning wood results in an increase in atmospheric CO 2. Charcoal: lighter than wood and contains approx. 2x as much energy per unit weight. Burning it produces less smoke. Manure: removes microorganisms from the surroundings but releases particulates and other pollutants into the air (CO and NO x )

Biofuels Ethanol: is an alcohol made by converting starches and sugars from plant material(usually corn) into alcohol and CO 2. Used in gasohol: 90/10 mix and produces less mileage/gal than gasoline alone! Biodiesel: is produced by extracting oil from algae and other plants like soy and palm. Used in B-20: a 80/20 mix of petroleum diesel and biodiesel. Cleaner than just p. diesel.

Hydroelectricity Hydroelectric power uses the kinetic energy of moving water to make electricity. Dams can be built to stop the flow of a river. Water behind a dam often forms a reservoir. Dams are also built across larger rivers but no reservoir is made. The river is simply sent through a hydroelectric power plant or powerhouse. Hydro is one of the largest producers of electricity in the United States. Water power supplies about 10 percent of the entire electricity that we use. In states with high mountains and lots of rivers, even more electricity is made by hydro power. In California, for example, about 15 percent of all the electricity is made this way. Also used in Washington and Oregon

How hydroelectricity works Moving water contains K.E. that turns a turbine. The turbines transform the the K.E. into electricity.

Tidal Energy

Pros and Cons of Hydroelectricity Pros: Once built they require little fossil fuel They generate large amount of electricity. Less expensive than nuclear energy or natural gas. Reservoir provides recreational and economic opportunities and downstream flood control.

Cons: Building a reservoir floods thousands of prime agricultural acres. May force people to relocate Free flowing rivers  standing water hold more heat and less O 2  changes ecosystem and lifecycles of certain aquatic species Release of greenhouse gases(methane) during dam construction and after filling the reservoir. Accumulation of sediments/siltation overtime lowers the water capacity and the electricity output of the dam.

Solar Energy Passive Solar Heating of buildings Active Solar technology (can generate hot water or electricity w/o producing air pollution, water pollution, or CO 2 in the process. Solar domestic Hot water systems Photovoltaic Solar Cells: can produce electricity during peak demand hours. But are very expensive to manufacture and install. Requires a variety of toxic metals in the building.

Passive Solar Design Home

Active Solar Energy Design

Geothermal Energy Is heat that comes from the natural radioactive decay of elements deep within the earth. Can be used directly as a source of heat Hot groundwater can be piped directly into household radiators for home heating. Returning water to the ground to be reheated is one way to use this energy sustainably.

Geothermal Energy creates steam that can turn turbines to create electricity.

Wind Energy is the most rapidly growing source of energy Convection currents of the air causes wind. A wind turbine converts the K.E. of moving air into electricity. The US has the largest wind energy generating capacity in the world, followed by Germany and Spain. Offshore wind conditions are most desirable.

Wind is a non-depletable clean and free energy source. It produces no pollution and no greenhouse gases. Wind farms can share the land with other uses like grazing. Some people find them ugly and noisy, and birds and bats may be killed by them. Off grid wind energy systems rely on batteries to store the energy

Hydrogen Fuel Cells have potential 2 H 2 + O 2  energy + 2H 2 O PROTONS FROM HYDROGEN GAS ARE FORCED THROUGH A MEMBRANE, WHILE THE ELECTRONS TAKE A DIFFERENT PATHWAY. THE MOVEMENT OF THE PROTONS IN ONE DIRECTION AND THE ELECTRONS IN ANOTHER, GENERATES AN ELECTRIC CURRENT. This require the use of electricity to make electricity.

Hydrogen Fuel Cell 80% efficient in converting the P.E. of hydrogen and oxygen into electricity and their only by product is water.

Improving the electrical Grid Electricity must be moved long distances from the power plant to the consumer. Along the way, 5-10% is lost in transmission. Batteries cannot store energy long term. We must develop a smart grid, an efficient, self regulating electricity distribution network that accepts any source of electricity and distributes it automatically to end users.

The Smart Grid