WEEK 1
Fuel gas is a fuel in the gaseous state whose potential heat energy can be readily transmitted and distributed through pipes from the point of origin directly to the place of consumption.
Natural gas (methane) is the most common fuel gas, but others include:
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Coal gas or Town gas
Syngas
Propane
Butane
Regasified liquified petroleum gas
Wood gas
Producer gas
Water gas
HCNG
Uncompressed Hydrogen or compressed hydrogen may be used as a fuel gas.

WEEK 2
Waste to Gaseous Fuels
Gaseous fuels may be derived from variety of wastes ranging from municipal and industrial wastes or from animal manure and solid biomass such as crop silage or the organic fraction of MSW. A number of processes allow these wastes to be transformed into gaseous fuels. Biogas, Syngas and Producer gas are the predominantly produced gaseous fuels. The pathways by which these gaseous fuels are produced can be represented schematically in figure.
MSW: Municipal Solid Waste (trash / garbage)
Syngas = Synthetic Gas (Hydrogen + Carbon Monoxide)

WEEK 3
Gaseous Fuels
Classification of Gaseous Fuels
Gas fuels are the most convenient requiring the least amount of handling and simplest and most maintenance free burner systems. Gas is delivered "on tap" via a distribution network and so is suited to a high population or industrial density. However large consumers do have gas holders and some produce their own gas.
The following is a list of the types of gaseous fuel:
(A) Fuels naturally found in nature:
Natural gas
Methane from coal mines
(B) Fuel gases made from solid fuel
Gases derived from Coal
Gases derived from waste and Biomass
From other industrial processes (Blast furnace gas)
(C) Gases made from petroleum
Liquefied Petroleum gas (LPG)
Refinery gases
Gases from oil gasification
(D) Gases from some fermentation process
Types of Gaseous Fuel
Natural Gas
Naturally occurring gas found in oil fields and coal fields (Fire damp). The quantities of the constituents vary but the principle component is methane. Other components include higher hydrocarbons which can be separated out as a condensate. Some gases also contain hydrogen sulphide.
Terms used to describe gases: dry or lean - high methane content (less condensate) wet - high concentration of higher hydrocarbons (C 5 - C 10 ) sour - High concentration of H 2 S sweet - low conc. of H 2 S residue gas - gas remaining after the condensing process

casing head gas - gas extracted from an oil well by extraction at the surface.
Natural gases can be liquefied for distribution by tanker. Liquefied natural gas (LNG) contains mostly methane, LPG (Liquefied petroleum gas) mostly butane and propane.
Synthetic Gases
These are gases which are chemically made by some process.
Increased interest presently in power generation due to the gasification properties of waste and biomass.
Main methods of synthesis:
Producer gas: The gas is produced by blowing air and sometimes steam through an incandescent fuel bed (the process is self heating). The reaction with air is exothermic but insufficient air is added hence CO is produced. Steam addition results in the formation of hydrogen by the water gas reaction. This is endothermic and hence balances out the exothermic air reaction.
Producer gas is low CV and is hence is only usually used on site
Blue Gas or Water Gas - This is produced in a similar manner to above but allows the production of a higher CV fuel by intermittently blasting the incandescent bed with air and steam such that the overall heat balance is maintained. The products of the air blast contain the nitrogen which reduces CV. These are discharged to atmosphere. The products of the steam blast are kept since they have a higher CV. CV is virtually doubled in this way. Often used as a synthesis gas in the chemical industry.
Oil Gas This is the gas formed by the thermal cracking of crude oil. If oil is sprayed onto heated checker work (refractory) it cracks to form lower gaseous hydrocarbons. These depend entirely on the feed stock but calorific values can increase to as much as
25MJ/m 3 but can be as low as half of this.
Carburetted Water Gas - Water gas has still to low a CV for most purposes and this makes it unattractive to distribute. Carburetted water gas is the result of combining the water gas and oil gas methods. Oil is sprayed into the hot water gas chamber to result in a good quality gas. The ratio of the two determines the quality. This was the method used to produce the "Town gas" of old and has largely been superseded by natural gas in countries with an abundant supply. AS supplies of natural gas diminish, however, it will become more important again.
Coal and Coke Oven Gas - As mentioned previously, gases are liberated in the high temperature carbonisation (coking) of coal. These are cleaned, de tarred and scrubbed and used as fuel. If coke is not required (coal gas), steam injection at the end of the cycle

reacts with the coke to form blue water gas. This reduces the CV of the gas produced but the thermal efficiency of conversion rises.
Gaseous Fuels ReVISITED
These fuels can be broken down into the following groups:
1 Naturally Occurring Gases
(i) The most volatile components of fossil fuel reserves
(a) From oil reserves
- gas direct from the oil fields (mostly methane)
- most volatile fraction from the distillation of oil, petroleum gas (mainly butane, propane)
(b) From coal reserves (Firedamp)
(ii) From the digestion of biomass by bacteria - Landfill gas, digester gas
2 Manufactured Gases
Gases derived from other feed stocks (solid or liquid)
(i) Pyrolysis, Carbonisation - The product of the heating of a solid or liquid to devolatilise the substance to form a char, coke or charcoal
- Coke oven gas
- Charcoal ovens
(ii) Gasification - The product of complete gasification of a solid or liquid feedstock - i.e. including the char. Only residue is ash.
- Producer gas - Low CV gas from partial combustion of coal in air
- Blue or Water Gas - Med. CV gas from gasification of coal with steam.
- Carburetted Water gas - Med. to High CV gas. Town gas.
- Oil gas - Formed by the cracking of heavy fuel oil.

The Importance of Gaseous Fuel
- Generally VERY clean burning. Little soot. Operate with low XSA.
- Easy to burn - No grinding or atomisation. Excellent mixing
- No problems with erosion or corrosion
- No ash
- The gas is easy to clean. E.g. if sulphur is present, it may be easily removed prior to combustion.
- Simplest combustion plant of all - Burners
- Control system
- No ash problems
- Heat exchangers
- Can be started up and shut down very easily and quickly.
- Problems with distribution and storage
- Explosion risk - very volatile.
- Relatively costly. Offset by cheaper and more efficient plant.
CONCLUSIONS
-Gaseous fuels play a vital part in modern energy demand
-Gas fuelled plant sets the standard of efficiency
-Of all fuels, gases are the easiest to burn and to clean
-Natural gas dominates all markets at present because of its abundance and quality.
-Gasification will begin to play an important role again in the future as gas reserves dwindle.
-Coal gasification technology is being developed on biomass plants with an aim to make a renewable gas source.

Glossary
Aquifer Storage Field: A sub-surface facility for storing natural gas consisting of water-bearing sands topped by an impermeable cap rock.
Biomass Gas: A medium Btu gas containing methane and carbon dioxide, resulting from the action of microorganisms on organic materials such as a landfill.
British Thermal Unit (Btu): The quantity of heat required to raise the temperature of 1 pound of water by 1 degree
Fahrenheit at the temperature at which water has its greatest density (approximately 39 degrees Fahrenheit).
Citygate: A point or measuring station at which a distributing gas utility receives gas from a natural gas pipeline company or transmission system.
Commercial Consumption: Gas used by nonmanufacturing establishments or agencies primarily engaged in the sale of goods or services. Included are such establishments as hotels, restaurants, wholesale and retail stores and other service enterprises; gas used by local,
State, and Federal agencies engaged in nonmanufacturing activities.
Consumption : Natural gas used as lease fuel, plant fuel, for use by pipeline and distribution systems, and by endusers
(including residential, commercial, industrial, electric power, and vehicle fuel).
Delivered: The physical transfer of natural, synthetic, and/or supplemental gas from facilities operated by the responding company to facilities operated by others or to consumers.
Depleted Storage Field: A sub-surface natural geological reservoir, usually a depleted oil or gas field, used for storing natural gas.
WEEK 6

Heating Season: Typically begins in October and runs through the end of March.
Industrial Consumption: Natural gas used for heat, power, or chemical feedstock by manufacturing establishments or those engaged in mining or other mineral extraction as well as consumers in agriculture, forestry, and fisheries. Also included in industrial consumption are generators that produce electricity and/or useful thermal output primarily to support the above-mentioned industrial activities.
Liquefied Natural Gas (LNG): Natural gas (primarily methane) that has been liquefied by reducing its temperature to -260 degrees Fahrenheit at atmospheric pressure.
Natural Gas: A gaseous mixture of hydrocarbon compounds, the primary one being methane. Note: The
Energy Information Administration measures wet natural gas and its two sources of production, associated/dissolved natural gas and nonassociated natural gas, and dry natural gas, which is produced from wet natural gas.
Pipeline: A continuous pipe conduit, complete with such equipment as valves, compressor stations, communications systems, and meters, for transporting natural and/or supplemental gas from one point to another, usually from a point in or beyond the producing field or processing plant to another pipeline or to points of utilization. Also refers to a company operating such facilities.
Propane-air: A mixture of propane and air resulting in a gaseous fuel suitable for pipeline distribution.
Residential Consumption: Gas used in private dwellings, including apartments, for heating, air-conditioning, cooking, water heating, and other household uses.
Total Storage Field Capacity: The maximum volume of base and working gas that can be stored in an underground storage facility in accordance with its design, which

comprises the physical characteristics of the reservoir, installed equipment, and operating procedures particular to the site.
Transmission (of natural gas): Gas physically transferred and delivered from a source or sources of supply to one or more delivery points.
Underground Gas Storage: The use of sub-surface facilities for storing gas that has been transferred from its original location. The facilities are usually hollowed-out salt domes, natural geological reservoirs (depleted oil or gas fields) or water-bearing sands topped by an impermeable cap rock (aquifer).
Unit Value, Consumption: Total price per specified unit, including all taxes, at the point of consumption.
Unit Value, Wellhead: The wellhead sales price, including charges for natural gas plant liquids subsequently removed from the gas, gathering and compression charges, and State production, severance, and/or similar charges.
Vehicle Fuel Consumption: Natural gas (compressed or liquefied) used as vehicle fuel.

WEEK 7
Christmas tree – The arrangement of pipes and valves at the wellhead to control the flow of oil or natural gas and to prevent blowouts. (See Wellhead)
CNG – Compressed Natural Gas
Completion – The procedure by which a successful well is readied for production.
Compressor station – Stations located along natural gas pipelines which recompress gas to ensure an even flow.
Conventional Resource – Any area where natural gas can be drilled and extracted vertically.
Derrick/Drilling Rig – A steel structure mounted over the borehole to support the drill pipe and other equipment that is lowered and raised during drilling operations.
Directional drilling – A technique that enables drilling at an angle to reach a particular underground formation.
Drilling permit – Authorization from a regulatory agency to drill a well.
Liquefied natural gas (LNG) – Natural gas that has been cooled into a liquid state so that it takes up only 1/600 of the volume of natural gas.
Liquefied petroleum gas (LPG) – Propane, butane or propane-butane mixtures derived from crude oil refining or natural gas fractionation. For convenience of transportation, these gases are liquefied through pressurization.
Natural gas – A naturally occurring mixture of hydrocarbon and non-hydrocarbon gases found in porous rock formations. Its principal component is methane.

Natural gas liquids (NGL) – A general term for liquid products separated from natural gas in a gas processing plant. These include propane, butane, ethane and natural gasoline.
Operator – The party responsible for exploration, development or production projects.
Pipeline – A string of interconnected pipe providing a route for natural gas to travel from the wellhead to market. Without pipelines, natural gas cannot be transported and sold at market to provide royalty payments, clean energy and economic benefits to the community.
Plug – A permanent plug, usually cement, set in a borehole to block the flow of fluids, to isolate sections of the well or to permanently plug a dry hole or depleted well.
Porosity – The open space within a rock, similar to pores in a sponge.
Sound Blanket – A sound blanket or a wall sometimes erected in order to reduce the noise emitted from a drilling rig.
Wellhead – The control equipment fitted to the top of the well, consisting of outlets, valves, blowout-prevention equipment, etc.
Working Interest – The right granted to the lessee of a property to explore for and to produce and own oil, gas or other minerals. The working interest owners bear the exploration, development and operating costs.
Unconventional Resource – Any area (shales, tight sands, fractured carbonates) where natural gas cannot be drilled and extracted vertically.

Storage and transport of natural gas
WEEKS 8 & 9
Polyethylene plastic main being placed in a trench.
Because of its low density, it is not easy to store natural gas or transport by vehicle.
Natural gas pipelines are impractical across oceans. Many existing pipelines in
America are close to reaching their capacity, prompting some politicians representing northern states to speak of potential shortages. In Europe, the gas pipeline network is already dense in the West.
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New pipelines are planned or under construction in
Eastern Europe and between gas fields in Russia, Near East and Northern Africa and
Western Europe. See also List of natural gas pipelines.
LNG carriers transport liquefied natural gas (LNG) across oceans, while tank trucks can carry liquefied or compressed natural gas (CNG) over shorter distances. Sea transport using CNG carrier ships that are now under development may be competitive with LNG transport in specific conditions.
Gas is turned into liquid at a liquefaction plant, and is returned to gas form at regasification plant at the terminal. Shipborne regasification equipment is also used.
LNG is the preferred form for long distance, high volume transportation of natural gas, whereas pipeline is preferred for transport for distances up to 4,000 km
(2,485 mi) over land and approximately half that distance offshore.

CNG is transported at high pressure, typically above 200 bars. Compressors and decompression equipment are less capital intensive and may be economical in smaller unit sizes than liquefaction/regasification plants. Natural gas trucks and carriers may transport natural gas directly to end-users, or to distribution points such as pipelines.
Peoples Gas Manlove Field natural gas storage area in Newcomb Township,
Champaign County, Illinois. In the foreground (left) is one of the numerous wells for the underground storage area, with an LNG plant, and above ground storage tanks are in the background (right).
In the past, the natural gas which was recovered in the course of recovering petroleum could not be profitably sold, and was simply burned at the oil field in a process known as flaring. Flaring is now illegal in many countries.
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Additionally, companies now recognize that gas may be sold to consumers in the form of LNG or CNG, or through other transportation methods. The gas is now re-injected into the formation for later recovery. The re-injection also assists oil pumping by keeping underground pressures higher.
A "master gas system" was invented in Saudi Arabia in the late 1970s, ending any necessity for flaring. Satellite observation, however, shows that flaring
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and venting
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are still practiced in some gas-extracting countries.
Natural gas is used to generate electricity and heat for desalination. Similarly, some landfills that also discharge methane gases have been set up to capture the methane and generate electricity.
Natural gas is often stored underground inside depleted gas reservoirs from previous gas wells, salt domes, or in tanks as liquefied natural gas. The gas is injected in a time of low demand and extracted when demand picks up. Storage nearby end users helps to meet volatile demands, but such storage may not always be practicable.

With 15 countries accounting for 84 per cent of the worldwide extraction, access to natural gas has become an important issue in international politics, and countries vie for control of pipelines.
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In the first decade of the 21st century, Gazprom, the stateowned energy company in Russia, engaged in disputes with Ukraine and Belarus over the price of natural gas, which have created concerns that gas deliveries to parts of
Europe could be cut off for political reasons.
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Floating Liquefied Natural Gas (FLNG) is an innovative technology designed to enable the development of offshore gas resources that would otherwise remain untapped because due to environmental or economic factors it is nonviable to develop them via a land-based LNG operation. FLNG technology also provides a number of environmental and economic advantages:
 Environmental – Because all processing is done at the gas field, there is no requirement for long pipelines to shore, compression units to pump the gas to shore, dredging and jetty construction, and onshore construction of an LNG processing plant, which significantly reduces the environmental footprint.
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Avoiding construction also helps preserve marine and coastal environments. In addition, environmental disturbance will be minimised during decommissioning because the facility can easily be disconnected and removed before being refurbished and re-deployed elsewhere.
 Economic – Where pumping gas to shore can be prohibitively expensive,
FLNG makes development economically viable. As a result, it will open up new business opportunities for countries to develop offshore gas fields that would otherwise remain stranded, such as those offshore East Africa.
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Many gas and oil companies are considering the economic and environmental benefits of Floating Liquefied Natural Gas (FLNG). However, for the time being, the only
FLNG facility now in development is being built by Shell, [52] due for completion around 2017.
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