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SHASHWAT VATSA B.Tech. APE(GAS ) UPES Dehradun.

Gas to Liquid Technology: Techniques, Prospects and Challenges UPES SPE FEST 201310 12February, 2013Gas Monetization alternatives:present scenario

What is GTL?

Gas to Liquids (GTL) conversion is an umbrella term for a group of technologies that can create liquid hydrocarbon fuels from a variety of feedstock such as biogas from waste, effluent anaerobic treatment, landfills, gas hydrates, coal bed methane (CBM), refinery gas and natural gas.

chemically converts natural gas into cleaner liquid fuels which can further be shipped to the market.

Converting natural gas to liquid fuels through well-known Fischer Tropsch (FT) synthesis not only eases the transportation facilities but also benefits the environment.

Drivers of the wonder technology

EVOLUTION: How it Developed Was first used in Germany during World War II as a motor fuel and by Sasol in South Africa(from 1955) to convert coal to synthesize gas and then oil after the basic technology was developed by German scientists FISCHER & TROPSCH in 1920. Over the years the technology has come up in a big way.

GTL Process: Flow diagram

MechanismThe Fischer-Tropsch process, using coal or natural gas, generally consists of three major steps. The process requires large energy streams, both for Syngas production & FT synthesis with significant production of low calorific value fuel gas. Overall efficiency depends upon the following steps discussed:1. Synthesis gas production :

CH4+ H2O ------------> CO + 3H2 ( H=206 kJ/ mol)

2. Syngas conversion to liquid fuel :

CO + 2H2 -----------> (CH2--) --- + H2O. (chain-growth mechanism)

The length of the chain and the product is determined by catalyst selectivity and the reaction conditions.

Although the process is quite complex, but a generalization study can be done as :

n CO + 2n H2 ---------------------> ---(--CH2 ---)n + n H2O ( -40kcal/gmol of CO) 2 n CO + n H2 ----------------------> ---(--CH2 ---)n + n CO2 (2 n-1) CO + (n+1) H2 ----------------> Cn H2N+1 OH + (n-1) CO2 (-30kcal/gmol of CO) n CO + 2n H2 -------------------------> H-(--CH2 ---)nOH + (n-1) H2O

Product up gradation and synthesis Conventional refinery processes are used for upgrading the FT liquid and wax products. Hydrocracking of large chained molecules is carried to break them into smaller units, followed by distillate hydro treating and catalytic reformation.

The synfuel composition depends on the reaction conditions such as H2 / CO ratio of syngas, temperature, pressure and catalyst type. At 330-350 deg. C, gasoline and olefins will be primarily produced. However if a temperature of 180-250 deg. C, will result in diesel and waxes. Typical operating pressures are 20-35 bars.

Refining of synthetic crudes derived from gas, is easy in many respects as compared to fossil fuels. Synthetic crude doesnt contain sulphur, nitrogen, metals, aromatics etc. Hence the final products are premium quality fuels, which are environmentally friendly.

Case study : Shells Pearl GTL

INDIA : Where does it stands Chief energy sources in the form of coal, hydel and at a domestic level biofuels.

Current GDP is 6.9% with 75% oil imported.

Current petroleum import bill is Rs. 5.11 lac crore.

outlook 2030 predicts, India and China together, will account the total increase in global coal demand, 94% of the net oil demand growth, 30% of gas growth demand and 48% of the net growth in non-fossil fuel

Span of 3.14 million square kilometres of sedimentary basins with 400 tcf of prognostic gas and 50 tcf coming from CBM.

COAL reserves estimated to be 118 billion tonnes. Gas produced from coal (CBM)is believed to increase the gas abundance by 15%.

84.9% of rural and 21.5% of urban households use biomass (firewood/dung cake etc.) based fuel in thermally inefficient and polluting mud stoves, while 66.9% households use solid biomass presently.

BIOMASS TO LIQUID ( BTL) : Indias Solution

Coal to liquid technology : the proven theory.With the kind of huge reserves , India has a true potential to go for Coal to Liquid projects.Coal gasification can be used to produce synthesis gas:Coal + O2 + H2O --------->H2+CO (Syngas)

Following factors favour the CTL projects to be realised in India :

Fuel independence from crude import.Ease of foreign currency crunch.Immunity to currency devaluation.Longevity due to huge Coal reserves.Employment generation. Development of rural and tribal areas. Economical at high international crude prices.

Economics of GTL..

3 vital components deciding the economics of an GTL project:1. Capital Cost 2. Operating cost 3. Raw material.GTL barrel may cost significantly less than the refined crude barrel, even with the current state of the technology.GTL costs have dropped to a point where they are almost similar to LNG which has a disadvantage in comparison . It requires specialist ships ($300 mill each) and re-gasification terminals at the discharge ports (+$600 million).

Both are not in competition. They serve different markets thus, an integrated approach towards LNG and GTL integration should be realised.

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The current and the future crude prices would ascertain the economic viability of a strong GTL industry.The plants rate of returns fluctuates from 10-28%, depending on the Brent crude prices. For a crude price range between $30-$60/ bbl., the cost of a refinery barrel ranges from $36-64 as compared to the GTL barrel cost of $18-32.

thedream barrel GTL AND ENVIRONMENTExcellent quality.No sulphur and clean fuel.High cetane No.Very low particulates& aromatics.Meets or exceeds all existing environmental specifications.Can be used in its pure form in existing engines as a low emission fuel but main use willbe as blend-stock in refinery production .25-30% blends with conventional diesel give disproportionately high reduction in emissions.

Barriers to the technology

GTL/ CTL / XTLProduces high value products Capital and operating costs for plants are decreasing.Integrated economics, with upstream gas resource are attractiveThank you