Energy Part 4 Energy Conservation and Renewables.
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Transcript of Energy Part 4 Energy Conservation and Renewables.
Energy Star Joint program between
the US EPA and the US DOE
Mission: to protect the environment through energy-efficient products and practices
Saved enough energy in 2005 equivalent to 23 million cars and $12 billion in utility bills
Corporate Average Fuel Economy (CAFE) Standards Average fuel economy (mpg) of a
manufacturer’s passenger cars and light trucks
Testing follows EPA guidelines Result in an estimated 55 billion gallons
annually and 10% reduction in carbon emissions
Achieved through better engine design, effciency, and weight reduction
Corporate Average Fuel Economy (CAFE) Standards Improvements to CAFE standards could be
achieved by expanding the standards to include: Streamlining Reduced tire-rolling resistance Engine improvements (ex: hybrid technology) Optimized transmission improvements Transition to high voltage automotive electrical
systems Preformance-based tax credits
Cars Cars should
Drive at least 300 miles between refueling Be refueled quickly Keep up with other traffic on the road (no moped effect)
Pros Cons
Gas Meets above standards
Poor gas millage
Pollution
Hybrid Electric Almost no pollution
Limited range between charges
Hybrid Electric Vehicles Attempt to increase mpg
while overcoming the shortcomings of an electric car
Parts of a gas-electric hybrid:
1. Gasoline engine (smaller than gas only cars)
2. Fuel tank3. Advanced electronics
allow electric motor to act as a generator
4. Generator acting only to produce electrical power
5. Batteries to store energy
Types of hybrid electric vehicles Parallel: Fuel tank supplies gas to the engine
and batteries supply electricity to the electric motor
Series: gasoline engine turns a generator which charges the batteries and/or power the electric motor; the gasoline engine never directly powers the car
Plug-in electric: hybrid cars with an added battery; can be plugged into a 120 volt outlet and charged; run on stored energy for up to (60 miles per charge)
Alternative Fuels (LNG and CNG) Natural Gas Vehicle (NGV) uses compressed
natural gas (CNG)
In 2010 there were 12.7 million natural gas vehicles world wide Pakistan had the most with 2.7 million Asia-Pacific region – 6.8 million Latin America – 4.2 million
Alternative Fuels (LNG and CNG) CNG require high compression and thick
walled tanks (adds cost and weight) CNG is cheaper than oil NGV corrode and wear the engine parts less
rapidly than gasoline (500,000 miles) on one engine is not uncommon
Emissions are cleaner There is less wasted fuel
Electric Cars
Uses an electric motor and electrical energy stored in batteries
Popular in the late 19th and early 20th centuries but were replaced by internal combustion engines
Renewed interest in electric cars due to climate change
Electric Cars
Pros Significant reduction of
urban air pollution Reduced green house
gasses Less dependent on
foreign oil
Cons More expensive than
conventional vehicles Due to cost of lithium-ion
battery Lack of private and
public recharging stations
Driver fear of running out of energy before reaching a recharging station
Mass Transit Types:
Rail Bus services Subways Ferries
Often determines where people live and work
How much air pollution people are subject to
US – only 3% frequently use mass transit
Japan – 47% Land availability
determines is cities expand vertically (no land – NYC) or horizontally (have land – LA) Determines preferred
mode of travel
Mass Transit Use rises with population density
Development of system determines efficiency of mass transit system
Most efficient method: promote a user-pay approach, where all external costs are factored into license fees and/or vehicle taxes
Types of mass transit
Light rail: trains that share space with road traffic and have own right-of-way and are separated from road traffic
Bus rapid transit: separate lanes, turnouts, signals, etc. for all busses
Types of mass transit - Car sharing short-term car rentals
Not limited by office hours, reservations, pickup and return are self-service
Can rent by hour or day Locations are distributed
throughout service area Insurance and fuel costs
are included in rates Near public
transportation
30% of households participated in car sharing
Help reduces congestion and pollution
Reduces demand for parking spaces
Only in high density areas
Types of Renewable Energy Solar Hydrogen Fuel Cells Biomass
Wind Energy Ocean Waves and Tidal
Energy Geothermal
Solar Collecting and harnessing
radiant energy from the sun to provide heat and/or electricity
Can be generated at home or in industrial settings Photovoltaic cells Solar collectors Solar-thermal plant
Solar Collectors
Active: collects and uses sun’s energy to heat water or air inside a home or business
Passive: structure is built to maximize solar capture Large south facing
windows
SolarPros Supply of solar energy is
limitless (for our purposes) Reduces reliance on foreign
imports Only pollution is in the
manufacture of collectors Can store energy during the
day and release it at night Small systems have a low
impact on the environment
Cons Inefficient where sunlight is
limited or seasonal Maintenance costs are high Systems deteriorate and
must be replaced periodically
Current efficiency is between 10% and 25%
Large systems can threaten wildlife – vaporize birds, etc.
Hydrogen 9 million tons of hydrogen is produce in US
each day Could power
20 – 30 million cars 5 – 8 million homes
Used by industry Refining Treating metals processing foods
Hydrogen Fuel Cell Operates similar to a battery
Two electrodes and a cathode separated by a membrane
Oxygen passes over one electrode and hydrogen over another
Hydrogen reacts with a catalyst that converts H2 gas
Hydrogen ions combine with oxygen
Electrons pass out of the battery
Hydrogen Fuel CellPros Waste product is pure water Ordinary water can be used
to obtain hydrogen Does not destroy wildlife
and has minimal environmental impact
Energy to produce hydrogen could come from a fusion reactor, solar, or less polluting source
Hydrogen is easily transported through pipelines
Hydrogen can be stored in compounds to make it safe to handle
Cons Takes energy to produce
hydrogen from water or methane
Changing from a current fossil fuel based system to hydrogen based would be very expensive
Hydrogen is an explosive gas
It is difficult to store hydrogen gas for personal cars
Biomass Any carbon-based,
biologically active fuel source Wood Manure Charcoal Biodiesel Methane ethanol
Approximately 15% of world energy is derived from biomass Burned in large incinerators
as an energy source
Most common in developing countries
Suitable plants for growing biomass Switch grass Hemp Corn Sugar cane
Can be used for building materials, biodegradable plastics, and paper
BiomassPros Renewable as long as used
sustainably Can be sustainable (control for
deforestation and erosion) Could supply half of world’s
energy demand Biomass plantations can be
located in less desirable locations to reduce soil erosion and restore degraded land
Crop residue are available as biomass
Ash can be collected and recycled
Reduces impact on landfills
Cons Requires adequate water and
fertilizer Use of inorganic fertilizers,
pesticides, and herbicides would harm the environment
Corn diverted to ethanol production raises food prices
Could cause massive deforestation
Inefficient burning methods could increase air pollution
Expensive to transport Not efficient (70% of energy
lost as heat) CO2 production would have
impact on climate change
Case Study - Biomass Bagasse: the fibrous
material that remains after sugarcane and sorghum stalks are crushed to extract the juice
Used for biofuel, paper, and building materials
10 tons of sugar cane yields 3 tons of bagasse
High moisture content (40 – 50%) makes it hard to use as a fuel
Used widely in Brazil
Using agricultural by-products for paper off sets commercial forestry reduces rate of rain forest conversion to commercial tree farms
Bagasse can be used to soak up oil spills and make disposable food containers, replacing styrofoam
Wind Energy The wind turns blades that turn a turbine to generate
power Wind farms: clusters of wind turbines
Wind EnergyPros All electrical needs of US
could be met by wind from (ND, SD, and TX)
Can be built quickly and built on sea platforms
Maintenance is low and farms are automated
Moderate – high net energy yield
No pollution Land underneath turbines
can be used for agriculture
Cons Steady wind is required to
make investment in wind farms economical – few suitable places
Back up systems need to be in place when wind is not blowing
Visual and noise pollution Interfere with flight patterns
of birds and bats – killing some
May interfere with communication such as TV and cell phone
Small-scale hydroelectric Utilizes small turbines
connected to submerged power generators to create electricity
100 kW or less capacity Factors to consider
Amount of consistent water available
Amount of drop between intake and output
Regualtory issues
Small-scale hydroelectric
Pros No pollution Does not impede
stream flow Does not stop fish
migrations Many economic
incentives for installing, grants, loans, tax incentives
Cons Low energy out put Suitable more for
remote areas than large scale energy production
Ocean Waves and Tidal Energy Uses natural movement of
tides and waves to spin turbines
Only a few in operation world wide
Pros: No pollution Minimal environmental impact Moderate net-energy
Cons: Construction is expensive Few suitable sites Equipment can be damaged
by storms or erosion
Geothermal
Heat contained in underground rocks and fluids from magma, dry-rock zones, and warm-rock reservoirs produce pockets of warm water or wet or dry steam
Steam drives a turbine engine Supplies less than 1% of world
energy Known resources tend to
follow tectonic plate boundaries
GeothermalPros Moderate net-energy
yield Limitless and reliable
source if managed properly
Little air pollution Completive cost
Cons Reservoir sites are
scarce Source can be depleted
if not managed properly Noise, odor, and land
subsidence Can degrade
ecosystem due to corrosive, thermal, or saline waste
Relevant Law Renewable Energy Law, China (2007):
Requires power grid operators to purchase resources from registered renewable energy producers
Offers financial incentives and discounted taxes and lending practices for renewable energy products
Designed to help protect the environment, prevent energy shortages, and reduce dependence on imported energy
Includes penalties for non compliance