renewable energy resources fossil fuels, electricity past present & future

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RENEWABLE ENERGY RESOURCES FOSSIL FUELS, ELECTRICITY PAST PRESENT & FUTURE

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RENEWABLE ENERGY RESOURCES

FOSSIL FUELS, ELECTRICITY

PAST PRESENT & FUTURE

KEY WORDS

Energy – being able to do work. e.g. food gives us energy, so that we can move

Fuel - Fuel is anything that is

burned or altered to obtain energy

Fuel gauge

ENERGY

“Some 2 billion people lack access to electricity and rely on traditional fuel sources such as firewood, kerosene, or biomass for their cooking and heating.”

4

ElectricityElectricity

• Electricity generation: fossil fuels and uranium

• Renewable energy is growing

Generation & Distribution

Renewable 21%

Nuclear 16%

Fossil fuels 63%

World electricity generation by energy

(US Energy Information Administration, 2004)

I. FOSSIL FUELS

Petroleum Natural Gas Coal Oil Shale and Tar Sands CO2 Emissions

ENERGY FROM FOSSIL FUELS

Fossil fuels are coal, oil and gas

Coal oil and gas

Fossil fuels were formed from

dead plants and animals over

millions of years.

fossils

ENERGY FROM FOSSIL FUELS

Fossil fuels have formed over millions of years. Plants and animals died and were immediately covered by sediment in seas or swamps.

After millions of years of pressure and heat (900C to 1200C), these remains turned into COAL, OIL and NATURAL GAS.

Coal comes mainly from dead plants, like trees, falling into swamps.

Oil and gas occur together and were formed from both plants and animals being buried.

When we burn fossil fuels we’re using the sun’s energy that has been stored as chemical energy underground for millions of years.

HOW ‘FOSSIL FUEL’ POWER STATIONS WORK:

Coal is crushed to a fine dust and burnt. Oil and gas can be burnt directly.

www.vauxhallsociety.org.uk

WHY USE FOSSIL FUELS TO MAKE ELECTRICITY?

Advantages Electricity can be generated fairly cheaply. Transporting oil and gas to the power stations is easy. Gas-fired power stations are very efficient. A fossil-fuelled power station can be built almost anywhere. 

Disadvantages Pollution. Burning any fossil fuel produces carbon dioxide, which

contributes to the "greenhouse effect", warming the Earth. Burning coal produces more carbon dioxide than burning oil or gas. Mining coal can be difficult, dangerous and ugly. Coal-fired power stations need huge amounts of fuel.

Fossil fuels are a non- renewable energy resource. Once we've burned them all, there isn't any more and our use of fossil fuels has nearly doubled every 20 years since 1900. This is a particular problem for oil, because we also use it to make plastics and many other products.

WORLD GREENHOUSE GAS EMISSIONS

HOLD DOWN CO2

The best way to hold down CO2 increases is to remove fossil fuels from electricity generation, but use it just for vehicles.

Since ½ of US electricity comes from coal which generates twice as much CO2 per energy unit as does natural gas, we should switch to natural gas. This, however, involves massive and possibly costly imports.

We need increases in alternate energy sources such as hydro, nuclear, wind and solar.

We also need increases in energy efficiency and conservation.

This especially includes high mileage vehicles.

CARBON IN FUELS: BILLIONS OF TONS OF C

INCREASING DEMANDS AND INCREASING DEMANDS AND CONSEQUENCESCONSEQUENCES Oil is extracted at the rate of 75 million barrels per

day, which means the current reserves are predicted to last only for another 35-40 years.

The cost of oil has already increased so much

COALCOALTHE ENERGY BRIDGE TO THE FUTURE!!THE ENERGY BRIDGE TO THE FUTURE!!

First fossil fuel to be discovered. Pushed to background because of its environmental

effects. The two major uses for coal – steel production and

electricity. Accounts for 23% of the global primary energy

demand, 38% of world electricity production and 70% of world steel production.

Major pollutants are volatile organic compounds (VOC), Nitrogen oxides (NOX), CO, SO2, particulate matter, mercury and lead.

Electric utility power plants 72%, 35%, and 33% of total emissions of SO2, CO2, and NOx.

Average mercury content of coal is 7.4 pounds per trillion Btu of energy input to the coal-fired electricity generator.

REVERTING TO COAL

For coal to reestablish itself as the primary fuel, it will need to reduce its environmental footprint.

Comparison of Air Pollution from the Combustion of Fossil Fuels

(kilograms of emission per TJ of energy consumed)

Natural gas Oil Coal

Nitrogen oxides

43 142 359

Sulphur di oxide

0.3 430 731

Particulates 2 36 1333

COMBINED CYCLE

Combines gas turbine and steam turbine.

Exhaust energy from gas section used in steam system.

High thermal efficiency.

Small plants combined.

GASIFICATIONGASIFICATION

Breaks down coal into basic chemical constituents.

Coal is exposed to hot steam and controlled amounts of air or oxygen under high temperature and pressures.

Carbon molecules in coal break apart, setting off chemical reactions that produce syn gas and other gaseous compounds.

Integrated gasification combined-cycle (IGCC) Syn gas is burned in a combustion turbine which

drives an electric generator. The exhaust gases are used to heat steam.

CARBON SEQUESTRATIONCARBON SEQUESTRATION It is a family of methods for capturing and permanently isolating

gases that could contribute to global climate change.

CARBON CAPTURE Pre-combustion capture Post-combustion capture Oxyfuel technologies. 

CARBON DIOXIDE SEQUESTRATION Industrial use of CO2 in plastics and other chemical industries Inorganic sequestration as carbonates Biological conversion to fuel Geological sequestration, in salt domes, or coal beds Injection into active oil wells Injection into exhausted gas or oil wells Ocean disposal

NATURAL GASNATURAL GAS The world had around 5500 trillion cubic meters

at the end of 2003.

Why Natural Gas? Cleaner fuel, has low carbon/hydrogen ratio hence less carbon dioxide

emission. Has a distinct hydrogen-rich molecular structure, hence supply hydrogen for

future technologies like fuel cells.

METHANE HYDRATE…THE GAS RESOURCE OF THE FUTURE

It is a compound of water and methane Forms under pressure at cold temperatures. Potential significant source of natural gas. Large volumes of hydrate based natural gas found

on Alaska's North Slope. Natural gas potential of methane hydrate approach

400 million trillion cubic feet.

• Climate change: Change of atmospheric conditions and its relationships with lithosphere, hydrosphere, and biosphere

• Atmosphere as a complex chemical factory: With many little-understood chemical reactions

• Changes in greenhouse gases, variable temp, and water vapor

ATMOSPHERE AND CLIMATE CHANGE

FIGURE 19.6

HEAT EXCHANGE WITHIN EARTH SYSTEMS

• Several atmospheric gases: CO2, CH4, CFCs trapping more heat and warming up the lower atmosphere, similar to the effect of a greenhouse

• The concentration of greenhouse gases increased recently due to human activities, anthropogenic gases

THE GREENHOUSE EFFECT

Reduce the emission of CO2

• Improved engineering technologies of fuel-burning power plants

• Use fossil fuels releasing less CO2

• Conservation of energy

• Store CO2 in forests, soils and rocks, depleted oil and gas fields, saltwater aquifers (sequestration of CO2)

• Use alternative energy

REDUCING THE IMPACT OF GLOBAL WARMING

Substitute 1400 natural gas electric plants for an equal number of coal-fired facilities

Fuel SwitchingFuel Switching

Photo by J.C. Willett (U.S. Geological Survey).

Triple the world’s nuclear electricity capacity by 2055

Nuclear ElectricityNuclear Electricity

Graphic courtesy of NRC

NUCLEAR POWER - ENERGY FROM SPLITTING URANIUM ATOMS

Nuclear power is generated using Uranium, which is a metal mined in various parts of the world.

Nuclear power produces around 11% of the world's energy needs, and produces huge amounts of energy from small amounts of fuel, without pollution.

electronicsdesigninfo.blogspot.com

ADVANTAGES OF USING NUCLEAR POWER

DISADVANTAGES

Solar ElectricitySolar Electricity

Photos courtesy of DOE Photovoltaics Program

Install 20,000 square kilometers for dedicated use by 2054

SOLAR POWER

Most of the Earth's energy comes from the sun Solar power is energy from the sun There are two main ways that we use the Sun's

energy 1. Solar Cells

2. Solar water heating

WHY USE SOLAR POWER?

Advantages Solar energy is free - no fuel, no waste or pollution. In sunny countries, easy to use in remote places Good for low-power uses such as solar powered garden

lights and battery chargers

Disadvantages Doesn't work at night. Very expensive to build solar power stations. Can be unreliable unless you're in a very sunny place Solar energy is renewable because the sun is

always there

Wind ElectricityWind Electricity

Install 1 million 2 MW windmills to replace coal-based electricity,

OR

Use 2 million windmills to produce hydrogen fuel

Photo courtesy of DOE

WIND POWER Wind power also comes from the sun; winds blow

because the Sun warms our atmosphere. Warm air tends to rise, and winds are due to other air moving in to replace it.

The wind blows the propeller round, which

turns a generator to produce electricity We tend to build many of these towers together, to

make a "wind farm" and produce more electricity. The more towers, the more wind, and the larger the

propellers, the more electricity we can make

WHY USE WIND POWER?Advantages Wind is free. Produces no waste or greenhouse gases. The land beneath can usually still be used for farming. Wind farms can be tourist attractions. A good method of supplying energy to remote areasDisadvantages The wind is not always predictable - some days have no wind. Suitable areas for wind farms are often near the coast, where

land is expensive. Some people feel that covering the landscape with these towers

is ugly Can kill birds. Can affect television reception if you live nearby. Can be noisy.  

Wind power is renewable. Winds will keep on blowing.

HYDRO-ELECTRIC POWER Hydro-electric power is generated from falling water. Nowadays

there are many hydro-electric power stations, providing around 20% of the world's electricity.

How it works: A dam is built to trap water, usually in a river valley. Water is allowed to flow through tunnels in the dam, to turn turbines

and thus drive generators to produce electricity.

(http://www.wvic.com/hydro-works.htm) 

WHY USE HYDRO-ELECTRIC POWER?

DISADVANTAGES

Hydro-electric power is renewable. The Sun provides the water by evaporation from the sea, and will continue to do it.

TIDAL POWER - ENERGY FROM THE SEA

How it works: Tidal Barrages These work rather like a hydro-electric scheme A huge dam (called a "barrage") is built across a river

estuary. When the tide goes in and out, the water flows through tunnels in the dam.

The ebb and flow of the tides can be used to turn a turbine.

ADVANTAGES OF TIDAL POWER

DISADVANTAGES OF TIDAL POWER

A barrage across an estuary is very expensive to build, and affects a very wide area. - the environment and birds. There are few suitable sites for tidal barrages.

Only provides power for around 10 hours each day, when the tide is actually moving in or out.

Tidal energy is renewable. The tides will continue to ebb and flow, and the energy is there for free.

Biofuels & BiomassBiofuels & Biomass

Photo courtesy of NREL

Scale up current global ethanol production by 30 times

BIOMASS - ENERGY FROM ORGANIC MATERIALS

Sugar cane can be used to make alcohol, which can be burned to generate power

Other solid wastes, can be burned to provide heat, or used to make steam for a power station

We can use rubbish, animal manure, woodchips, seaweed, corn stalks and other waste

Advantages It makes sense to use waste materials where we can. The fuel tends to be cheap. Less demand on the Earth's resources.

 

Disadvantages Collecting the waste in sufficient quantities can be

difficult. We burn the fuel, so it makes pollution. Some waste materials are not available all year round.

Biomass is renewable, as we're going to carry on making waste products. We can always plant and grow more sugar cane and more trees, so those are renewable too.

GEOTHERMAL ENERGY IS ENERGY FROM HEAT INSIDE THE EARTH.

How it works Hot rocks underground heat water to produce steam.

We drill holes down to the hot region; steam comes up, is purified and used to drive turbines, which drive generators to make electricity.

Geothermal energy is an important resource in volcanically active places such as Iceland and New Zealand.

ADVANTAGES

DISADVANTAGES

ENERGY STORAGE SYSTEMS

IMPORTANCE OF ENERGY STORAGE SYSTEMS...

Thrust for Renewable Energy sources Variable outputs new technologies and devices?

DIFFERENT TYPES OF ENERGY STORAGE SYSTEMS

Mechanical Energy Storage. Magnetic Energy Storage. Thermal Energy Storage. Chemical Energy Storage.

“ The path to the future is neither as rosy as some people hope nor as thorny as others fear, but depends on how effectively we pick out the weeds and nurture the bush as we walk ”