Embracing New Renewable Energy for a Sustainable Future

1. Chapter 13 • Achieving Energy Sustainability

2. “New” renewable energy sources • The economic, social, and environmental impacts of fossil fuels are intensifying • “New” renewables are a group of alternative energy sources that include the sun, wind, geothermal heat, and ocean water • They are referred to as “new” because: • They are not yet used on a wide scale • Their technologies are still in a rapid phase of development • They will play a much larger role in our future energy use

3. New renewables provide little of our energy • New renewables provide energy for electricity, heating, fuel for vehicles • Renewables provide only 1% of energy and 18% of our electricity • Nations vary in the renewable sources they use • Most U.S. renewable energy comes from hydropower

4. The new renewables are growing fast • They are growing faster than conventional energy sources • Wind power is growing at 50% per year • Since these sources began at low levels, it will take time to build them up In 2008, we added more energy from renewables than from fossil fuels and nuclear power

5. Use has expanded quickly because of: • Growing concerns over diminishing fossil fuel supplies • Environmental and health impacts of burning fossil fuels • Advances in technology make it easier and cheaper • Benefits of the new renewables include: • Alleviating air pollution and greenhouse gas emissions • They are inexhaustible, unlike fossil fuels • They help diversify a country’s energy economy • They create jobs, income, and taxes, especially in rural areas

6. New energy sources create jobs • New technologies need labor • Generating more jobs than a fossil fuel economy • Rapid growth will continue as: • Population and consumption grow • Energy demand increases • Fossil fuel supplies decline • People demand a cleaner environment Green-collar jobs = design, installation, maintenance, and management of renewable energy technologies

7. Policy can accelerate our transition • Can we switch soon enough to avoid damaging our environment and economy? • Technological and economic barriers prevent rapidly switching to renewables • Remaining barriers are political • Conventional sources get more government subsidies and tax breaks • Cheap fossil fuels hurt renewables • Businesses and industries are reluctant • Short-term profits, unclear policy signals

8. What is renewable energy? • Renewable energy can be rapidly regenerated, and some can never be depleted, no matter how much of them we use. • Nondepletable resources are ones that will still remain no matter how much we use them.ex. Wind, solar, hydroelectric, geothermal • Potentially renewable- an energy source that can be regenerated indefinitely as long as it is not overharvested. ex. biomass

10. Energy Consumption in Developing Countries • Only 22.3% of global population lives in developed countries • These people consume 68% of commercial energy • Each person in a developed country consumes 7.4x’s as much energy as person in a developing country

11. 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. • Energy efficiency- getting the same result from using a smaller amount of energy.

13. Benefits of Conservation and Efficiency • To avoid blow outs or blackout during high use periods of electricity, electric companies must be able to provide energy to satisfy peak demand • 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. • Peak demand for electricity is between 12 noon and 6 p.m. • Most consumers are awake, working and needing heat or air conditioning. It is also the time many manufacturers are powering machinery. • Variable price structure- utility customers can pay less to use energy when demand is lowest and more during peak demand.

14. SustainableDesign • Improving the efficiency of the buildings we live and work in. • Direct solar energy is used to: • Heat houses and buildings • Heat water • Create high temperature heat • Create electricity

15. Passive Solar Energy • Technique that takes advantage of solar radiation to maintain a comfortable temperature in the building • Using passive solar energy can lower your electricity bill without the need for pumps or other mechanical devices. • Based on Architectural Design • Considers exposure direction, windows, building materials, eaves • Requires no energy to use • Building the house with windows along a south-facing wall which allows the Sun’s rays to warm the house would be an example.

18. California Academy of Sciences in San Francisco-showcase of several techniques in sustainable design and used 30% less energy than Federal code allows. Passive solar design, radiant heating, solar panels, skylights, green roof.

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

21. Biomass • Wood, Charcoal and Manure- used to heat homes throughout the world. • Ethanol and Biodiesel (biofuels)- used as substitutes for gasoline and diesel fuel.

22. Biopower generates electricity Many types of biomass are combusted to generate electricity • Waste products of industries or processes • Woody debris, crop residues • Specifically grown crops (fast-growing willow trees, bamboo) • Co-firing combines biomass and coal • Gasification turn biomass to steam • Pyrolysis produces a liquid fuel

23. Scales of production • Farmers, ranchers, or villages use manure, wood waste, or biogas from digestion to generate electricity • Small household biodigesters work in remote areas • The U.S. has dozens of biomass-fueled power plants • Biomass power increases efficiency and recycling • It reduces CO2 emissions and dependence on imported fossil fuels • It is better for health and supports rural economies • But burning crops deprives the soil of nutrients • Relying only on bioenergy is not a sustainable option

24. Ethanol can power automobiles • Ethanol = a biofuel made by fermenting carbohydrate-rich crops • Ethanol is added to U.S. gasoline to reduce emissions • In 2009, 10 billion gallons were made in the U.S. from corn • Congressional mandates will increase ethanol production

25. Cars can run on ethanol • Flexible-fuel vehicles run on E-85 • 85% ethanol, 15% gasoline • 8 million cars are in the U.S. • Most gas stations do not yet offer this fuel • Bagasse = crushed sugarcane residue used to make ethanol • 50% of new Brazilian cars are flexible-fuel vehicles

26. Ethanol may not be sustainable • Environmental scientists don’t like corn-based ethanol • Growing corn impacts ecosystems • Pesticides, fertilizers, irrigation • Takes up land that could be left unfarmed • Ethanol competes with food and drives up food prices • As farmers shifted to ethanol, corn for food dropped • Mexicans could not afford tortillas, and so they rioted • Growing corn requires energy for equipment, pesticides, and fertilizers • Its EROI ratio is about 1.5:1, so it is inefficient

27. Biodiesel powers engines • Biodiesel = produced from vegetable oil, cooking grease, or animal fats • Vehicles can run on 100% biodiesel • B20 = 20% biodiesel • Biodiesel reduces emissions • Its fuel economy is good • It costs a bit more than gasoline • Crops are specially grown • Using land, deforestation

28. Novel biofuels are being developed • Algae produce lipids that can be converted to biodiesel • Their carbohydrates can be fermented to make ethanol • It can be grown in ponds, tanks, or photobioreactors • Algae grows fast and can be harvested every few days • It can use wastewater, ocean or saline water • It can capture CO2 emissions to speed its growth • Biofuels from algae are currently expensive

29. Two novel biofuels • Cellulosic ethanol = produced from structural plant material (e.g., corn stalks) that has no food value • Switchgrass provides ethanol, habitat, and high EROI Switchgrass provides fuel now and may provide cellulosic ethanol Algae is a candidate for a next-generation biofuel

30. Is bioenergy carbon-neutral? • In principle, biomass energy releases no net carbon • Photosynthesis removes carbon that is released when biomass is burned • Burning biomass is not carbon-neutral: • If forests are destroyed to plant bioenergy crops • If we use fossil fuel energy (tractors, fertilizers, etc.) • The Kyoto Protocol gives incentives to destroy forests for biofuel crops • Only emissions from energy use (not land-use changes) are “counted” toward controlling emissions

31. Modern Carbon vs. Fossil Carbon • Many people are confused how burning biomass such as wood is better then burning coal. • 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 • 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.

35. 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.

37. 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. • Water impoundment- water is stored behind a dam and the gates of the dam are opened and closed controlling the flow of water. • Tidal systems- the movement of water is driven by the gravitational pull of the Moon. In areas of EXTREME tides, electricity can be generated from tides

38. A run-of-river system

40. Coastal onshore facilities • One coastal design uses rising and falling waves, which push air in and out of chambers, turning turbines to generate electricity • No commercial wave energy facilities operate yet • But demonstration projects exist in Europe, Japan, and Oregon

41. Hydroelectric power is widely used • Hydropower accounts for 2.2% of the world’s energy supply • And 15.6% of the world’s electricity production • Nations with large rivers and economic resources have used dams • However, many countries have dammed their large rivers • People want some rivers left undammed • The U.S. government built dams to employ people and help end the economic depression of the 1930s • Engineers exported their dam-building techniques

42. Hydropower is clean and renewable • Hydropower has two clear advantages over fossil fuels for producing electricity: • It is renewable: as long as precipitation fills rivers we can use water to turn turbines • It is clean: no carbon dioxide is emitted • Hydropower is efficient • It has an EROI of 10:1 • As high as any modern-day energy source

43. Hydropower has negative impacts • Damming rivers destroys wildlife habitats • Upstream areas are submerged • Downstream areas are starved of water • Natural flooding cycles are disrupted • Downstream floodplains don’t get nutrients • Downstream water is shallower and warmer • Periodic flushes of cold reservoir water can kill fish • Dams block passage of fish, fragmenting the river and reducing biodiversity • Large dams can cause earthquakes or collapse

44. Hydropower may not expand much more • China’s Three Gorges Dam is the world’s largest dam • It displaced 1 million people • Generates as much electricity as dozens of coal-fired or nuclear plants • Most of the world’s large rivers have already been dammed • People have grown aware of the ecological impact of dams and resist more construction • Developing nations with rivers will increase hydropower

47. The Sun’s energy can be captured directly • Active solar energy- capturing the energy of sunlight with the use of a pump or photovoltaic cell and generating electricity. • Uses mechanical power and pumps to circulate water or air • A heat absorbing fluid is heated in the sun and then directed to where it is needed • It is not restricted to wealthy, sunny regions

49. Photovoltaic cells generate electricity • Photovoltaic (PV) cells = convert sunlight directly into electrical energy • The photovoltaic (photoelectric) effect occurs when light hits the PV cell and hits a plate made of silicon • Released electrons are attracted to the opposite plate • Wires connecting the two plates let electrons flow, creating an electric current • Small PV cells are in watches and calculators • On roofs, PV cells are arranged in modules, which comprise panels gathered into arrays