Chapter 13 Achieving Energy Sustainability

Renewable Energy Renewable energy can be rapidly regenerated, and some can never be depleted, no matter how much of them we use

How can we use less energy? Energy conservation – finding ways to use less energy – Ex: lowering your thermostat during the winter or driving few miles in your car Energy efficiency – getting the same result from using a smaller amount of energy

Global Energy

U.S. Energy

Reducing Energy Use

Benefits of 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) Variable price structure – utility customers can pay less to use energy when demand is lowest and more during peak demand

Sustainable Design Sustainable design can improve the efficiency of the buildings we live and work in LEED (Leadership in Energy and Environmental Design) is a voluntary program that provides third-party verification of green buildings

LEED Rating System Sustainable sites credits encourage strategies that minimize the impact on ecosystems and water resources Water efficiency credits promote smarter use of water, inside and out, to reduce potable water consumption Energy & atmosphere credits promote better building energy performance through innovative strategies Materials & resources credits encourage using sustainable building materials and reducing waste Indoor environmental quality credits promote better indoor air quality and access to daylight and views

Solar Energy Passive solar energy – a design that collects heat as the sun shines through south-facing windows and retains it in materials that store heat Thermal inertia – ability of a material to retain heat or cold Using passive solar energy can lower your electricity bill without the need for pumps or other mechanical devices

Radnor Middle School

Hillside Elementary School

Modern Carbon vs. Fossil Carbon Carbon found in biomass was in the atmosphere as CO 2, then taken in by the tree, and by burning it we put it back into the atmosphere Carbon in coal has been buried for millions of years and was out of “circulation” until we mined it – This results in a rapid increase in the concentration of CO 2 in the atmosphere

Modern Carbon Cycle

Biomass Solid biomass fuels: – Wood – Charcoal – Manure Used to heat homes and cook food throughout the world

Biomass – Wood Benefits Can be sustainable, if harvested appropriately Can increase species diversity in harvested forests Inexpensive Drawbacks Often harvested unsustainably Increases soil erosion, stream water temperature, and habitat fragmentation Releases PM, CO, and NO x when burned

Unsustainable Tree Harvesting

Biomass – Charcoal Benefits Lighter and more energy dense than wood Produces less smoke than wood Drawbacks More expensive than wood Releases PM, CO, and NO x when burned

Biomass – Manure Benefits Kills microorganisms found in manure Inexpensive Renewable Drawbacks Releases PM, CO, and NO x when burned

Liquid Biomass Liquid biomass fuels: – Ethanol – Biodiesel Biofuels are used as substitutes for gasoline and diesel fuel

Biofuels – Ethanol Benefits Promotes energy independence Emits fewer pollutants than gasoline Is “carbon neutral” Drawbacks Contains less energy than gasoline Currently made mostly from corn, a food staple Requires energy to grow and process

Biodiesel Bus

Biofuels – Biodiesel Benefits Promotes energy independence Emits less CO than regular diesel Is “carbon neutral” Can be generated from used cooking oil Algae holds a lot of potential Drawbacks More expensive than regular diesel Requires energy to grow and process

Kinetic Energy in Water Hydroelectricity – electricity generated by the kinetic energy of moving water Is the 2 nd most common form of renewable energy in the world

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

Hydroelectric Dam

Types of Hydroelectric Power Systems Run-of-the-river systems – water runs through a channel before returning to the river

Run-of-the-river System

Types of Hydroelectric Power Systems Tidal systems – the movement of water is driven by the gravitational pull of the Moon

Where in the U.S. is solar energy the greatest?

Solar Energy Passive solar energy - capturing the energy of sunlight without the use of a pump or photovoltaic cell

Solar Energy Active solar energy – capturing the energy of sunlight with the use of a pump or photovoltaic cell and generating electricity

Concentrating Solar Thermal System

Geothermal Energy Geothermal energy – using the heat from natural radioactive decay of elements deep within Earth, as well as heat coming from Earth

Where in the U.S. is geothermal energy the greatest?

Wind Energy Wind energy – using a wind turbine to convert kinetic energy into electrical energy

Where in the U.S. is wind energy the greatest?

Offshore Wind Resources

Hydrogen Fuel Cells Fuel cell – a device that operates like a common battery, where electricity is generated by a reaction between two chemicals

PA Renewable Energy The State’s Alternative Energy Portfolio Standards require 18% of electricity sold by 2021 to come from renewable or approved alternative sources, including at least 0.5% solar photovoltaic power In 2011, renewable energy accounted for 3.3% of Pennsylvania’s net electricity generation

Energy Practice Problem #1 You used 1,500 kWh over a 30-day period. a)Find the energy used, in kJ, for the 30 day period. 1,500 kWh 1 kW 1,000 W 60 min 1 h 60 s 1 min1,000 J 1 kJ = 5,400,000 kJ J/s 5,400,000 kJ = 5.4 × 10 6

Energy Practice Problem #1 You used 1,500 kWh over a 30-day period. b)Find the energy used in J/day. 180,000,000 J/day = 1.8 × 10 8 J/day

Energy Practice Problem #1 You used 1,500 kWh over a 30-day period. c) At the rate of $0.07/kwh, what will your electric bill be for this month? $105.00

Energy Practice Problem #2 Suppose your 400 watt lights are used for 4 hours per day, every day for one year. a) How many kWh per year does this represent? 400W × (1kW/1,000W) × (4h/d) × (365 d/yr) = 584 kWh/yr

Energy Practice Problem #2 Suppose your 400 watt lights are used for 4 hours per day, every day for one year. b) If you replaced your lights with fluorescent bulbs that only used 60 watts, what savings in kWh does this represent in one year? 340W × (1kW/1,000W) × (4h/d) × (365 d/yr) = kWh/yr