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

Case Study – Bloom Boxes Collection of solid oxide fuel cells that use liquid

or gaseous hydrocarbons to generate electricity on site

20% of cost savings results from avoiding transfer cost over grid

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