FUEL ALTERNATIVES :1) H.F.O. : Heavy fuel oil also known as high Sulphur fuel oil with max. Sulphur content of 3.5% m/m2) L.S.F.O.: Low Sulphur fuel oil This fuel oil had a max. Sulphur content of 1.0% m/m and was required to be used by ships entering SECA until 31st Dec. 2014 . Now this fuel is no longer acceptable for SECA but can be used outside SECA .3) U.L.S.D. : Ultra Low Sulphur Diesel Also known as MDO or MGO . This distillate fuel has a max. Sulphur content of 0.1% and is required to be used by ships entering SECA from 1st Jan. 2015 . 4) LNG/CNG : Diesel engines can be converted to run on Natural Gas (methane) as fuel by either using lean burn technology or high pressure gas injection . In both the cases pilot diesel fuel injection is required . In the first case engine can be run on about 50-70% NG while in second case it can be run on upto 95% NG . The advantages are high calorific value giving more power output , reduced CO2 emissions , reduction in SOx , NOx , PM though there is some methane slip causing an increase in the THC released and increased CO emissions . 5) LPG: Diesel engines (CI engines) can be converted to run on LPG as fuel . LPG is mixed with air in the inlet manifold and sent alongwith air into the combustion chamber where it is compressed to a high pressure and temperature . But unlike diesel fuel , LPG has a high auto-ignition temperature and it will not ignite until a pilot diesel injection is done near the TDC . Due to pilot injection the combustion starts and the LPG is ignited by pilot fuel combustion . LPG reduces knocking , provides smooth power output , reduces PM & THC emissions , 6) Ethanol : Also known as E-diesel . It can be used in pure form or can be mixed with petro-diesel in varying proportions to obtain the blend . Some additives are required to make the blend stable . CI engines burning Ethanol have to be redesigned with a compression ratio of about 1:28 compared to those normal diesel engines having a compression ratio of 1:17 . Ignition improvers may be required for better engine efficiency as ethanol has a high ignition delay . An alternative method of NOx reduction is to be used to ensure emission are within the limits as burning ethanol fuels at higher temperatures causes increased NOX formation . Oxidizing catalysts are added to the E-diesel to eliminate the CO & HC emissions . However overall carbon footprint of using Ethanol or E-diesel is low as it recirculates the carbon . But from safe handling point of view , E-diesel has lower flash point than petro-diesel and currently cannot be used in the machinery spaces until SOLAS regulations are suitably modified .7) Synthetic Diesel : This is produced by various carbonaceous substances like biomass , biogas , natural gas , coal etc. The raw material is gasified to form synthesis gas and then converted by Fischer Tropsch process to synthetic diesel . This has zero sulphur content and very low aromatic content and thus SOx , THC , NOx and PM emissions are reduced 8) Bio-diesel (FAME-Fatty Acid Methyl-esters) : These are obtained from vegetable oil or animal fats which are trans-esterified with methanol . The trans-esterification uses catalyst ,such as sodium pr potassium hydroxide , to convert vegetable oil and methanol into FAME and byproducts glycerine and water which have to be removed from FAME alongwith traces of methanol . FAME can be used as pure Bio-diesel or can be mixed with diesel . Use of Bio-diesel gives zero Sox emissions , reduced unburned HC , CO and PM . CO reductions are upto 50% when compared with petro-diesel , PM is reduced by about 30% and Total HC (THC) emissions are reduced by about 93% compared with normal diesel . however they give lot of problems like system corrosion , conducive environment to microbiological growth , poor oxidation stability causing degradation of fuel etc. The energy content is low and power loss can be upto 5-7% . They give greater NOx emissions also . Overall they reduce the health risks associated with carcinogenic substance emission released by burning petro-diesels .

Some Theory On Hydrocarbon Combustion

Hydro carbonStateBurn%AtmosphericBurn

pressure

Methane C1H4Gas99.70%Combustion starts with a bang and finishes with a fizzExplosive

Ethane C2H6Gas99.50%Combustion starts with a bang and finishes with a fizzHighly Flammable (plus)

Propane C3H8Gas99%Combustion starts with a bang and finishes with a fizzHighly Flammable

Butane C4H10Gas98%Combustion starts with a bang and finishes with a fizzFlammable + Hot Burn

PetrolLiquid97.50%Combustion starts with a fizz and finishes with a bangBurn

Kerosene (Paraffin)Liquid90%Combustion starts with a fizz and finishes with a bangSlow burn

DieselLiquid82%Combustion starts with a fizz and finishes with a bangV Fast Fizz

Light engine oilLiquid78%Combustion starts with a fizz and finishes with a bangNeeds to be heated before combustion

Source : http://www.gaspoweruk.co.uk/diesellpgbifuel/diesellpgbifuel.htmlFUEL TYPENCV (MJ/Kg)COST- USD/MTCOST-USD/MMBTU

HFO403007.92

MGO42.747011.62

LNG49.321322.83