IASNOVA
Shale gas
Unlike conventional gas, which resides in highly porous and permeable reservoirs and can be easily tapped by standard vertical wells, shale gas remains trapped in its original source rock, the organic-rich shale that formed from the sedimentary deposition of mud, silt, clay, and organic matter on the floors of shallow seas.
The development of hydraulic fracturing technology (also known as hydrofracturing, hydrofracking, or simply fracking) has also improved access to shale gas deposits. This process requires injecting large volumes of water mixed with sand and fluid chemicals into the well at high pressure to fracture the rock, increasing permeability and production rates. (Already asked in Prelims)
It’s a difficult and costly process.
Coalbed Methane
Coalbed methane (CBM or coal-bed methane is a form of natural gas extracted from coal beds.In recent decades it has become an important source of energy in United States, Canada, Australia, and other countries.
The term refers to methane adsorbed into the solid matrix of the coal. It is called ‘sweet gas’ because of its lack of hydrogen sulfide. The presence of this gas is well known from its occurrence in underground coal mining, where it presents a serious safety risk. Coalbed methane is distinct from a typical sandstone or other conventional gas reservoir, as the methane is stored within the coal by a process called adsorption. The methane is in a near-liquid state, lining the inside of pores within the coal (called the matrix). The open fractures in the coal (called the cleats) can also contain free gas or can be saturated with water.
Unlike much natural gas from conventional reservoirs, coalbed methane contains very little heavier hydrocarbons such as propane or butane, and no natural-gas condensate. It often contains up to a few percent carbon dioxide.
Tight gas
Tight gas refers to natural gas that has migrated into a reservoir rock with high porosity but low permeability.
These types of reservoirs are not usually associated with oil and commonly require horizontal drilling and hydraulic fracturing to increase well output to cost-effective levels.
Biogenic gas
Certain types of bacteria, known as methanogens, can produce methane, the chief component of natural gas, in the process of breaking down organic matter in an oxygen-free environment.
This type of gas is call “biogenic” to differentiate it from the “thermogenic” or fossil gas produced from organic material buried in the Earth’s crust at high temperatures and pressures. The properties of biogenic methane are identical to those of thermogenic methane.
Livestock manure, food waste, and sewage are all potential sources of biogenic gas, or biogas, which is usually considered a form of renewable energy.
Biofuels
A biofuel is a fuel that is produced through contemporary biological processes, such as agriculture and anaerobic digestion. If the source biomatter can regrow quickly, the resulting fuel is said to be a form of renewable energy.
Biofuels can be derived directly from plants (i.e. energy crops), or indirectly from agricultural, commercial, domestic, and/or industrial wastes. Renewable biofuels generally involve contemporary carbon fixation, such as those that occur in plants or microalgae through the process of photosynthesis. Other renewable biofuels are made through the use or conversion of biomass . This biomass can be converted to convenient energy-containing substances in three different ways: thermal conversion, chemical conversion, and biochemical conversion.
Biofuels are in theory carbon-neutral because the carbon dioxide that is absorbed by the plants is equal to the carbon dioxide that is released when the fuel is burned.
Bioethanol is an alcohol made by fermentation, mostly from carbohydrates produced in sugar or starch crops such as corn, sugarcane, or sweet sorghum.
Jatropha curcas – a poisonous shrub-like tree that produces seeds considered by many to be a viable source of biofuels feedstock oil.
Syngas
Syngas, a mixture of carbon monoxide, hydrogen and other hydrocarbons, is produced by partial combustion of biomass, that is, combustion with an amount of oxygen that is not sufficient to convert the biomass completely to carbon dioxide and water.Before partial combustion, the biomass is dried, and sometimes pyrolysed. The resulting gas mixture, syngas, is more efficient than direct combustion of the original biofuel; more of the energy contained in the fuel is extracted.
Algal Biofuel
Algae biofuel is an alternative to liquid fossil fuels that uses algae as its source of energy-rich oils. Algae fuels are an alternative to commonly known biofuel sources, such as corn and sugarcane.
Like fossil fuel, algae fuel releases CO2 when burnt, but unlike fossil fuel, algae fuel and other biofuels only release CO2 recently removed from the atmosphere via photosynthesis as the algae or plant grew. The energy crisis and the world food crisis have ignited interest in algaculture (farming algae) for making biodiesel and other biofuels using land unsuitable for agriculture.
Among algal fuels’ attractive characteristics are that
- they can be grown with minimal impact on fresh water resources
- can be produced using saline and wastewater,
- have a high flash point,
- and are biodegradable and relatively harmless to the environment if spilled.
Algae can be used to produce ‘green diesel’ through a hydrotreating refinery process that breaks molecules down into shorter hydrocarbon chains used in diesel engines.
Research into algae for the mass-production of oil focuses mainly on microalgae (organisms capable of photosynthesis that are less than 0.4 mm in diameter, including the diatoms and cyanobacteria) as opposed to macroalgae, such as seaweed. The preference for microalgae has come about due largely to their less complex structure, fast growth rates, and high oil-content (for some species). However, some research is being done into using seaweeds for biofuels, probably due to the high availability of this resource.
Species of Alage suitable for Biofuel Production-
Botryococcus braunii
Chlorella
Dunaliella tertiolecta
Gracilaria
Pleurochrysis carterae (also called CCMP647).[78]
Sargassum.
Geothermal Energy
Geothermal energy is the natural heat of the earth. Earth’s interior heat originated from its fiery consolidation of dust and gas over 4 billion years ago. It is continually regenerated by the decay of radioactive elements, that occur in all rocks.
From the surface down through the crust, the normal temperature gradient – the increase of temperature with the increase of depth – in the Earth’s crust is 17 °C — 30 °C per kilometer of depth (50 °F — 87 °F per mile).
Major geothermal fields are situated in circum-pacific margins, rift zones of East Africa, North Africa, Mediterranean basin of Europe, across Asia to Pacific.
There are four major types of Geothermal energy resources.
- Hydrothermal
- Geopressurised brines
- Hot dry rocks
- Magma
Currently, hydrothermal energy is being commercially used for electricity generation and for meeting thermal energy requirements.
Shale Gas ,Coalbed Methane ,Tight Gas in India
India has got technically recoverable shale gas of 96 trillion cubic feet.
The recoverable reserves are identified in-
Cambay,
Krishna – Godavari,
Cauvery,
Damodar Valley,
Upper Assam,
Pranahita – Godavari,
Rajasthan and
Vindhya Basins.
The Oil and Natural Gas Corporation has drilled the first exploratory shale gas well in Jambusar near Vadodara, Gujarat, in Cambay basin during October 2013.
MoU have been signed between USA and India for sharing technical knowledge in shale-gas exploration.
In addition to shale gas, India has got reserves of other unconventional natural gases like Coal Bed Methane, Coal Mine Methane, and Tight Gas which are in the different stages of development/production. The CBM is extracted from virgin coal mines.
At present CBM is produced from four blocks –
- Jharia in Jharkhand,
- Raniganj East
- Raniganj South in West Bengal and
Sohagpur West in Madhya Pradesh.
It is estimated that India may produce about 5.5 million standard cubic meters of CBM by the end of this year which could be about 5 percent of the total natural gas production in the country. At present Coal Mine Methane is not trapped and is blown out of coal mines.
Tight Gas reservoirs in Eocene formations in Gujarat and Northeast India have been discovered.
Geothermal Energy in India
There are seven geothermal provinces in India :
- Himalayas,
- Sohana,
- West coast,
- Cambay,
- Son-Narmada-Tapi (SONATA),
- Godavari, and
- Mahanadi.
- Most promising site in India- Puga valley of Ladakh.
- The discovery of vast geothermal reservoirs at Puga in the north-west of the Himalayas and Tatapani fields on the Narmada in central India .
- India’s Gujarat state is drafting a policy to promote geothermal energy.
Ongoing Geothermal Projects in India:
- Tattapani geothermal area in Madhya Pradesh
- Puga geothermal area in Ladakh region, Jammu & Kashmir
