Achieving Energy Sustainability Chapter 13

Current Energy Usage US Energy Use Global Energy Use

RENEWABLE ENERGY The European Union aims to get 20% of its all energy from renewable sources by 2020 Costa Rica gets 92% of its energy from renewable resources. China aims to get 10% of its total energy from renewable resources by 2020.

Electricity from RENEWABLE ENERGY In 2014, Germany generated 75% of electricity with a combination of renewable sources Denmark now gets 40% of its electricity from wind and plans to increase this to 100% by 2050. In 2004, California got about 12% of its electricity from wind and plans to increase this to 50% by 2030.

Jobs & Economy: Renewable Energy According to the American Council for an Energy-Efficient Economy (ACEEE), robust investment in energy efficiency: could save $1.2 trillion by 2020, and the United States could create 1.3 to 1.9 million jobs by 2050 through the deployment of energy efficient technologies The International Renewable Energy Agency (IRENA) estimates that 5.7 million people worldwide were employed in the renewable energy sector, directly and indirectly, in 2012. The largest number of jobs is found in biofuels and solar photovoltaic, 1.38 million and 1.36 million, respectively

Energy Use Conservation - Reducing energy waste is quickest, cleanest, cheapest way to provide more energy, reduce pollution reduce environmental degradation, preserve our dwindling supply of resources Evaluate efficiency Incandescent light bulb: wastes 95% Car motor: wastes 80% Nuclear power plant: wastes 86% Coal burning power plant: wastes 66% Solution: Reduce waste & increase Efficiency

Wasted Energy Unavoidable: Avoidable: 41% of US Commercial energy is “lost” when energy changes form (2nd law of thermodynamics) usually heat lost to the environment Avoidable: 43% of energy is wasted unnecessarily, by inefficient motors, appliances, wasteful usage 1st law of thermodynamics: conservation of energy – energy is neither created nor destroyed, just changes form 2nd law of thermodynamics: When energy changes form, energy quality decreases. We end up with less usable energy

Energy Efficient Appliances Bulbs: To make same amount of light Incandescent : 60 Watts Fluorescent : 15 Watts LED : 8 Watts Heat pumps 40 % electricity to produce same amount of heat Solar water heaters : Reduce energy use by 50%

Living Roofs Roofs covered with plants have been used for decades in Europe and Iceland. These roofs are built from a blend of light-weight compost, mulch and sponge-like materials that hold water. Figure 17-10

Saving Energy in Existing Buildings About one-third of the heated air in typical U.S. homes and buildings escapes through closed windows and holes and cracks. Figure 17-11

Efficient Design Example: CA Academy of Sciences Building Passive Solar Design South-facing double-paned windows with adjustable shades Overhang blocks summer sun, but winter sun enters windows Heat absorbant floor: and heat is stored and slowly released in stone or concrete floors

Designing Buildings: Green Architecture Other design features Super insulate Geothermal cooling / heating Utilize breeze /wind for ventilation and cooling Roof color: light colors reflect sunlight, dark colors absorb and store heat Green roofs with soil and vegetation reduce cooling costs, create habitat, absorb runoff and improve air quality Double paned windows and strong insulation to prevent heat loss Recycled building materials Trees for shade Skylights and natural lighting Radiant heating in floors Energy efficient appliances

ENERGY EFFICIENCY: Cars The government Corporate Average Fuel Economy (CAFE) Enacted in 1977 after Arab Oil Embargo Has not increased since 1985. Stuck at 25 mpg for 30 years Scheduled to increase to 35mph in 2016 Figure 17-5

How do we achieve energy sustainability? Increase energy efficiency – Fossil fuels will last longer and renewables will be able to support a larger portion of our energy needs. Invest in a wide variety of energy sources – Provides stability and diversity Shift subsidies away from fossil fuels to support research and development of renewables – will make renewables more cost effective and the transition away from fossil fuels less damaging Full cost pricing – Externalities include the social, environmental and health costs of an energy source in its price. Will even the economic playing field between fossil fuels and renewables

Capacity and Peak Demand We have to plan our energy capacity around peak demand Capacity is the amount of energy a power plant can provide at any given moment Peak demand – most energy used at one time: can be many times normal use Reducing peak demand is a key component of energy sustainability Options: Increase energy efficiency Conservation during energy transfers Tiered pricing plans Store energy (batteries, water uphill, solar heating) Back up generators Smart Grid: Smarter systems that automatically adjust energy usage to avoid blackouts and brownouts and that spread out energy usage

Power Grid/Smart Grid http://www.pbslearningmedia.org/resource/nvel.sci.tech.smart/toward-a-smarter-grid/ http://www.pbslearningmedia.org/resource/nsn11.sci.engin.systems.smartgrid/smart-power-grid/

Renewable Energy

Biomass Biomass is organic material from plant and animal Direct burning : Wood, manure, MSW, crop residue, charcoal, etc Convert to different forms: methane (natural gas) – decomposing organic waste ethanol (gasohol) - fermenting organic material from corn, sugarcane, switchgrass, or agricultural residue biodiesel - oil extracted or collected from waste oil, soybeans, algae, etc

Biomass Potentially renewable Carbon neutral Rate of harvesting < rate of growth Max Sustainable Yield Otherwise: Deforestation Carbon neutral Biomass is part of current carbon cycle Stored & released in short time frame Theoretically, no net increase in atmospheric carbon Fossil fuels: Carbon has been locked away for millions of years Rapidly releasing what has been slowly accumulating Results in Net increase in CO2 in atmosphere

Biomass Low-tech High-tech Solid Biomass: wood, charcoal, manure heating & cooking  Indoor Air Pollution High-tech Liquid & Gas Biomass Biofuels: Ethanol, Biodiesel, Biogas vehicles & electricity generation

Gas Biofuel: Biogas Organic wastes go in  bacteria convert to methane  biogas harvested for use.

Biogas from Methane Digestion Biogas (methane) is an important renewable gas fuel made by fermenting organic wastes, (animal dung), in a digester but can contribute to climate change. Biogas uses less land than other biofuels and thus reduces the amount of deforestation, runoff, soil erosion, and energy consumption. Biogases occur in things like landfills or agriculture and produces a strong smell but with methane digestion the amount of methane released to the atmosphere is reduced. If the waste is not going to landfills then there is a reduction in the amount of waste as well. Saprophytic bacteria (facultative anaerobes) break down fats, proteins, and polysaccharides Biogas What is the source of methane digestion? Other environmental benefits of methane digestion: reduction of runoff from manure into waterways, reduction of manure form that needs to be disposed of in landfills, reduction in the use of fossil fuels for electricity. Acid forming bacteria break down these monomers to short chain organic acids Digester BIOGAS Methane 50-80% CO2 15-45% Water 5% Methanogen bacteria (strict anaerobes) produce methane gas

Liquid Biofuel Types: Ethanol (fermented sugar) Corn (US ) Sugar cane (Brazil leads) Switchgrass (promising on marginal land) Biodiesel (extracted oil) Soybeans Palm Oil (Southeast Asia) ALGAE!!! WINNER!!

Algae Grow Fast Have High Biofuel Yields Consume CO2 Don’t Compete With Agriculture Microalgal Biomass Can Be Used or Fuel, Feed and Food Can Be Grown in the Sea Can Purify Wastewaters Can Be Used to Produce Many Useful Products The Algae Industry is a Job Creation Engine

Biofuel Downsides  crops for fuel vs. crops for food (takes food away from people) Agricultural expansion  land footprint  deforestation (esp. soy & palm in the tropics) Crops have fossil fuel input (mechanized monoculture uses lots of fuel/fertilizer/pesticide)

http://c1gas2org. wpengine. netdna-cdn http://c1gas2org.wpengine.netdna-cdn.com/files/2008/05/biofuels_compare.gif

Biomass: Environmental Impacts Use of crops and crop land for fuel – creates competition for land and increases food prices Growing crops for fuel creates all the problems associated with commercial agriculture Fossil fuel dependent, fertilizer runoff, pesticides, soil degradation, etc Impacts can be decreased by Growing less intensive grasses on marginal land Using waste material (trash, crop residue or logging waste) Using algae which can be grown in brackish water, on rooftops, or other non-traditional agriculture spaces and creates more fuel per area

Large potential supply in some areas Trade-Offs Solid Biomass Advantages Disadvantages Large potential supply in some areas Nonrenewable if harvested unsustainably Moderate to high environmental impact Moderate costs No net CO2 increase if harvested and burned sustainably CO2 emissions if harvested and burned unsustainably Low photosynthetic efficiency Plantation can be located on semiarid land not needed for crops Soil erosion, water pollution, and loss of wildlife habitat Figure 17.24 Natural biomass capital: making fuel briquettes from cow dung in India. The scarcity of fuelwood causes people to collect and burn such dung. However, this practice deprives the soil of an important source of plant nutrients from dung decomposition. Plantations could compete with cropland Plantation can help restore degraded lands Often burned in inefficient and polluting open fires and stoves Can make use of agricultural, timber, and urban wastes Fig. 17-25, p. 405

Hydropower Using the potential energy of flowing water to generate electricity Renewable / Nondepletable suitable sites are limited and we are maxed out in terms of conventional dams There is little room for expansion in the U.S. – Dams and reservoirs have been created on 98% of suitable rivers. new technologies emerging for using tides and waves

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. 7% of the electricity in the US…more than ½ of this is in the states of CA, WA, OR China is the world’s leader in hydroelectricity followed by Brazil and the US.

Captures kinetic energy and uses it to turn a turbine. Amount of electricity depends on the distance it falls or the flow rate or both. Biggest dam: In US: Grand Coulee Dam in Washington In China: Three Gorges Dam on Yangtze River

Hydroelectric Dam Dam Transformer Sluice gate Powerhouse Generator Reservoir Penstock Turbine Dam Afterbay

Types of Hydropower Water wheels Run of the river Systems used to grind grain or cut wood ancient practice Run of the river Systems Water runs through a channel and dam to create a small amount of electricity (water turns turbine) Subject to flooding and drought so electricity production can vary as river flow changes Water Impoundment Dams Dam a river to create a large water gradient and water storage area (lake) Falling water turns a turbine  electricity Major up and downstream impacts http://commons.wikimedia.org/wiki/File:Waterwheel_2.png http://www.worldwatch.org/hydropower-central-america-renewable-sustainable-and-without-alternatives

Types of Hydropower Pumped Storage Systems excess electricity is used to pump water upstream (storing potential energy) can then be used to generate extra electricity during peak hours

Types of Hydropower Tidal Energy Uses the changing tides to turn a turbine Tides are a very reliable source of energy Energy captured both directions Need to protect fish

Types of Hydropower Wave Power Use the movement of waves to run a generator Concerns about ocean habitat disruption Not as reliable as the tides

Wave Power Power module 145 m Each module produces 250 kW of electricity 3.5 m 145 m Wave tube Anchor Power cable Feeds electricity back to land Each power module is connected by hinges and attached to hydraulic rams. As the wave tube moves up and down, the rams shift hydraulic fluid in the power module and drive a turbine and generator.

Dams: Environmental Impacts Upstream Major reservoir is created upstream to provide drinking water, irrigation, recreation and flood control Massive flooding changes habitat entirely and displaces native plants, animals and people Siltation: Sediment build up behind the dam requires dredging Standing water holds more heat, have less oxygen and more water is lost to evaporation Downstream Reduced water flow may alter riparian, wetland and estuary habitats which alter flora and fauna Lack of nutrients from blocked sediments reduces soil fertility Loss of seasonal water flow (changes estuaries and flooding patterns) Dam itself Fragments habitat Disrupts fish migration Increased anaerobic decomposition (decomp under water) creates methane and CO2 Blocks fish migration (can be helped with fish ladders)

Trade-Offs Large-Scale Hydropower Moderate to high net energy Advantages Disadvantages Moderate to high net energy High construction costs High environmental impact from flooding land to form a reservoir High efficiency (80%) Large untapped potential High CO2 emissions from biomass decay in shallow tropical reservoirs Low-cost electricity Long life span Floods natural areas behind dam No CO2 emissions during operation in temperate areas Converts land habitat to lake habitat Figure 17.20 Trade-offs: advantages and disadvantages of using large dams and reservoirs to produce electricity. QUESTION: Which single advantage and which single disadvantage do you think are the most important? May provide flood control below dam Danger of collapse Uproots people Provides water for year-round irrigation of cropland Decreases fish harvest below dam Decreases flow of natural fertilizer (silt) to land below dam Reservoir is useful for fishing and recreation Fig. 17-20, p. 400

Geothermal Energy stored below the earth’s surface can be harvested for heat and energy Nondepletable although some sites can be temporarily depleted of hot water Can be used directly as a source of heat/hot water or indirectly to produce electricity. Direct use can happen almost anywhere, but sites for electricity production are limited. Common in Iceland and currently practiced in the western US

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. Wherever magma comes close enough to ground water, the ground water is heated. Where it does not rise to the surface naturally (Yellowstone geysers, etc.) humans may be able to reach it by drilling. US, China, and Iceland have substantial geothermal resources and are the largest producers of geothermal energy. Iceland: 87% of their home heating, 20% of it’s electricity. US 5% of its renewable energy.

Types of Geothermal Energy Low Temperature – used directly for hot water or space heating Hot water used for cooking or normal hot water uses – water may or may not go back into reservoir Hot water is disseminated via a heat exchanger to heat buildings – water back into reservoir to be reheated and used again Ground source heat pumps – constant temps underground transfer heat from underground . Requires energy to pump fluid. Winter: heat from underground is used to heat a fluid which transfers heat to the house, fluid is then reheated Summer: fluid cooled underground absorbs heat in the house and then transfers the warmer fluid underground where it loses heat High Temperature – used to produce electricity High pressure steam  turns turbine  makes electricity  water back into reservoir to reheated and used again Just like a coal plant, but no burning required

Ground source heat pump Can be installed anywhere regardless of whether there is geothermal energy

Geothermal Plant

Geothermal Suitability Ground Source Heat Pumps can be used anywhere Sites for direct use are somewhat limited Sites for electricity generation are significantly limited to areas with high geologic activity http://www.nevadageothermal.com/s/Geothermal.asp 47

Geothermal in TX According to a report by the Southern Methodist University Geothermal Laboratory, the hot water and pressure between 8,000 and 25,000 feet below Texas could supply more than 100 times the state's 2008 total electric consumption for well over a century.

Environmental Impacts Geothermal heat and steam contain traces of gases (H2S, SOx, etc) that can be harmful to humans and the environment Sulfur compounds from geothermal plants can lead to acid rain (but generally less than fossil fuel power plants) Reduced by using scrubbers to clean out harmful gases or collecting the gases for useful purposes Remote and pristine habitats can be fragmented or impacted by road construction, drilling, etc to access the geothermal reservoirs

Geothermal Power Advantages of geothermal power include: high efficiency moderate CO2 emissions low cost (in suitable areas) low environmental impact Disadvantages of geothermal power include: few suitable sites noise and odor pollution depleted easily if not managed land subsidence due to extracted water

Solar Power Capturing radiant energy from the sun to generate light, heat and electricity. Cannot be depleted Amount varies depending on latitude, cloud cover, time of day and season Two Types Active – using technology to capture the sun’s energy often changing the form Examples: solar panels, solar water heating, concentrated solar plants Passive - Using the sun’s energy to heat or cool without energy inputs, pumps or special technology Examples: windows and blinds, solar oven

Solar Energy

Solar Power FRQ 2006 #1: Describe one environmental benefit and one environmental cost of photovoltaic systems.

Solar Power FRQ 2006 #1: Describe one environmental benefit and one environmental cost of photovoltaic systems.

Active: Photovoltaics Photovoltaic cells convert radiant energy from the sun into electricity Cells are composed of silicon with phosphorus and boron. Photons strike the solar panel and excite electrons to create a flow of electrons Electrons flow through the semiconducting materials to create electricity Electricity can be stored in batteries for use at night Price of photovoltaic cellss is high, but dropping

Photovoltaic cell can be installed on roofs to provide electricity Individual Solar cell A solar cell converts light into electric current. The energy that is generated is usually converted directly to electricity which is stored in a battery or used to heat water. On their first tests the solar cells were only about 1% efficient (similar to photosynthesis). Since the increase in technology the percent efficiency has gone from 1% to 5% to 20% to 40% and now some designs are reporting 85% conversion efficiency. Photovoltaic cell can be installed on roofs to provide electricity

Producing Electricity with Solar Cells Single solar cell Solar-cell roof – + Boron enriched silicon Roof options Junction Figure 17.17 Solutions: photovoltaic (PV) or solar cells can provide electricity for a house or building using solar-cell roof shingles, as shown in this house in Richmond Surrey, England. Solar-cell roof systems that look like a metal roof are also available. In addition, new thin-film solar cells can be applied to windows and outside walls. Phosphorus enriched silicon Panels of solar cells Solar shingles Photovoltaic (PV) cells can provide electricity for a house of building using solar-cell roof shingles.

Producing Electricity with Solar Cells Solar cells can be used in rural villages with ample sunlight who are not connected to an electrical grid. Figure 17-18

It is possible to get electricity from solar cells that convert sunlight into electricity. Can be attached like shingles on a roof. Can be applied to window glass as a coating. Can be mounted on racks almost anywhere.

Active: Solar hot Water System A heat collecting liquid is heated on the roof and transferred to the water storage tank where it heats the water. Fluid returns to the roof to be reheated. Setup costs associated with buying and installing the system, but then you get free hot water (still have to pay the water itself though) May require energy to pump the water around

Active: Concentrated Solar Thermal Systems Power Towers Rotating mirrors track and aim sunlight at a tower Fluid collects heat to make steam to generate electricity Parabolic Troughs Reflective troughs focus sunlight on a fluid filled tube which heats up to make steam to generate electricity Large land requirements: Usually placed in a desert habitat with no trees and year round sun Some threats to fragile desert ecosystems Do not produce electricity at night Go To: http://ca.pbslearningmedia.org/asset/ate10_int_newsolar/

Passive Solar Absorbs & stores heat from the sun directly within a structure Window placement (under an overhang to let winter sun in and keep summer sun out) Windows (double or triple paned with low e glazing to prevent heat loss) Flooring (concrete or stone with good thermal inertia to absorb and store heat) House orientation (south facing in the US) Insulation (sufficient to keep heat in or out) Albedo effect (dark colors to absorb heat, light colors to reflect it) Green roof Deciduous tree for shade in summer (no leaves in winter Building into side of hill

Passive Solar

Solar Suitability

Passive or Active Solar Heating Trade-Offs Passive or Active Solar Heating Advantages Disadvantages Energy is free Need access to sun 60% of time Net energy is moderate (active) to high (passive) Sun blocked by other structures Quick installation Need heat storage system No CO2 emissions Very low air and water pollution High cost (active) Figure 17.14 Trade-offs: advantages and disadvantages of heating a house with passive or active solar energy. QUESTION: Which single advantage and which single disadvantage do you think are the most important? Very low land disturbance (built into roof or window) Active system needs maintenance and repair Moderate cost (passive) Active collectors unattractive

Wind Energy the most rapidly growing source of electricity Nondepletable convert wind (kinetic) into electricity Wind turns a turbine directly to create a flow of electrons

Wind Turbines & “Wind Farms” Best in rural areas with lots of wind Must be near transmission lines Requires lots of land, but land can be used for other things (farming, ranching, habitat) or they can be placed off shore.

Wind energy capacity: US has the largest capacity, followed by Germany, China, India, and Italy. US only produces 1% of its electricity via wind. Denmark: largest user at 21% of their electricity

Land Turbines Pros Cons Clean, inexpensive energy source that runs off of a nondepletable energy source Can share space with other land uses: ranching/farming Cons Requires lots of space Noisy/eye sore Threatens migrating birds and bats Public resistance Not suitable everywhere Construction costs/metal Requires a back-up source or batteries for storage

Offshore Wind Farms Turbines located 3-20 miles off shore Offshore winds are stronger and often more reliable Concerns include Impact on marine wildlife during construction and possibly operation Impact on bird and mammal migration Transfer of electricity (loss over longer distances)

Wind Suitability

Hydrogen and oxygen are combined to produce electricity Hydrogen Fuel Cells Hydrogen and oxygen are combined to produce electricity 2 H2 + O2 → energy +2 H2O No pollution! Only water vapor Continues to produce electricity as long as supplied with fuel http://www.scientificamerican.com/article.cfm?id=hydrogen-house

Hydrogen Fuel Cell Car Benefit: 80% efficient - H2O only waste product Problem: H2 gas is rare in nature – Have to generate using energy (electrolysis) & explosive – dangerous for collisions with H2 tanks, have to build distribution network Hydrogen for Cars - http://ca.pbslearningmedia.org/asset/eng06_vid_fuelcells/

The Economics of Renewable Energy

Future Energy Solutions Energy use in the near future will be a mix of renewable and non renewable energies. As technology improves, current renewable energy sources will become more efficient and more common. A move away from large central power producers will see an increase in more efficient regional power producers. Household energy production, such as home solar water heating or battery storage, will play a major part in meeting the world’s future energy demands. Renewable energy technologies will continue to become more efficient and affordable. Water heating and electricity needs will increasingly become the task of small home based solar power devices.

Energy Solutions Government strategies Subsidize energy resources to encourage use: tax breaks, rebates, research grants, regulations to stimulate development Raise price to discourage use: tax, eliminate subsidies, regulations to restrict development Public education: advantages and availability Develop long range policies to transition to more sustainable energy sources

Energy: Source vs Use

Good Study Resource for Energy