New Energy Alternatives New Renewables Commonly referred to as new because: not used on a wide scale technologies that are still in development believed that they will play a large role in the future Chapter 21 The Human Environment ( B I O 1 1 6 ) 5/10/2007 Chapter 21: New Energy Alternatives 2 New Renewables Solar: from the sun s rays Wind: from the wind Geothermal: from heat and heated water beneath the ground Ocean sources: from the tides and from waves Hydrogen: fuel and fuel cells that store renewable energy in usable form Renewable Sources: Outlook Currently = Only 0.5% of our global energy supply The outlook for renewable sources is good Solution for global climate change? Economical benefits Gets cheaper as more people promote/ use 5/10/2007 Chapter 21: New Energy Alternatives 3 5/10/2007 Chapter 21: New Energy Alternatives 4
Growth of New Renewable Sources Solar Energy Use of energy from the sun Raw energy is very strong Technologies still in development Passive solar = smart design of buildings to maximize solar energy variations Active solar = uses devices to focus, move, or store solar energy solar panels, PV cells 5/10/2007 Chapter 21: New Energy Alternatives 5 5/10/2007 Chapter 21: New Energy Alternatives 6 Solar Energy: Active Solar Solar Energy: PV cells Photovoltaic cells (PV cells) convert solar energy directly into electrical energy 5/10/2007 Chapter 21: New Energy Alternatives 7 5/10/2007 Chapter 21: New Energy Alternatives 8
Pros and Cons of Solar Power PROS: Renewable as long as sun keeps on shining Sun s energy abundant, if technology can capture it Allows for local control over power Solar cookers in developing nations lessen workloads. No direct greenhouse gas emissions CONS: Not everywhere is sunny enough Up-front investment cost is high; takes years to pay for itself Wind Power Takes kinetic energy of wind and converts it to electrical energy Fastest growing power source today Wind turbines machines with turning blades that convert wind energy into electricity by spinning a generator 5/10/2007 Chapter 21: New Energy Alternatives 9 5/10/2007 Chapter 21: New Energy Alternatives 10 Wind Power: Wind Turbines Wind Power Most wind power so far is concentrated in a few nations. 5/10/2007 Chapter 21: New Energy Alternatives 11 5/10/2007 Chapter 21: New Energy Alternatives 12
Wind Power: Wind Farms Pros and Cons of Wind Power PROS: Renewable as long as wind blows No emissions after equipment made, installed Can allow local decentralized control over power, and local profit from electricity sales Costs low after initial investment; costs dropping CONS: Not everywhere is windy enough. Windy sites can be far from population centers. Some people object to aesthetics. Blades kill birds, bats. High start-up costs 5/10/2007 Chapter 21: New Energy Alternatives 13 5/10/2007 Chapter 21: New Energy Alternatives 14 Hydrogen Hydrogen = simplest and most abundant element in universe Could potentially serve as basis for clean, safe, efficient energy system How it would work: Electricity generated from intermittent renewable sources produces hydrogen Fuel cells can then use hydrogen to produce electricity Production of Hydrogen Fuel Hydrogen gas (H 2 ) does not exist freely on Earth We need to make it Requires an energy input Electrolysis is the cleanest way: Split water into hydrogen and oxygen: 2 H 2 O 2 H 2 + O 2 This can potentially be very clean, releasing no greenhouse gas emissions 5/10/2007 Chapter 21: New Energy Alternatives 15 5/10/2007 Chapter 21: New Energy Alternatives 16
Production of Hydrogen Fuel Cleanliness of hydrogen production depends on the source of electricity Hydrogen can also be produced from organic molecules like fossil fuels greenhouse emissions hydrogen production could have environmental impacts of its own Ozone issues? Hydrogen Fuel Cells Hydrogen fuel cells produce electricity by joining hydrogen gas and oxygen The reaction is simply the opposite of electrolysis: 2 H 2 + O 2 2 H 2 O How it works: Hydrogen molecules are stripped of electrons H + ions move through a membrane Electrons complete a circuit, creating electricity 5/10/2007 Chapter 21: New Energy Alternatives 17 5/10/2007 Chapter 21: New Energy Alternatives 18 Hydrogen Fuel Cells Pros and Cons of Hydrogen Fuel PROS: CONS: We will never run out of hydrogen. Can be clean and nontoxic, with no greenhouse gas emissions Fuel cells potentially convenient, safe, and efficient Depending on way hydrogen is produced, it may not be environmentally clean Emission of hydrogen to atmosphere might have unforeseen impacts 5/10/2007 Chapter 21: New Energy Alternatives 19 5/10/2007 Chapter 21: New Energy Alternatives 20
Conclusion Renewable energy sources with sustainability promise include solar, wind, geothermal, and ocean. By using electricity from renewable sources to produce hydrogen fuel, we may be able to use fuel cells to produce electricity when and where it is needed. Most renewable energy sources have been held back due to lack of funding and artificially cheap market prices for nonrenewable resources. Despite this, renewable technologies have progressed far enough to offer hope for a shift away from fossil fuels. 5/10/2007 Chapter 21: New Energy Alternatives 21