Last Updated on: 21/12/2022

Q.1 What is Green Hydrogen?

The Green hydrogen is the hydrogen produced by electrolysis of water, using renewable power. The green hydrogen production is the new approach towards attaining net zero emission as this process does not emit any greenhouse gas to environment.

The conventional process for production of Hydrogen is steam methane reforming (SMR) which is known as Grey hydrogen, emits about 10 kg of CO2 per kg of hydrogen produced. If the CO2 generated in the SMR gas is captured, then the hydrogen produced is called Blue hydrogen.

Q.2 What are the other different colours of Hydrogen

In the other colours of hydrogen based on the source and the process used are Turquoise hydrogen, pink hydrogen, brown hydrogen, white hydrogen, yellow hydrogen, Gold hydrogen etc.

Turquoise Hydrogen: Hydrogen Produced through thermal splitting/ pyrolysis of methane.

Yellow Hydrogen: Hydrogen produced through electrolysis using grid electricity.

Pink Hydrogen: Hydrogen produced through electrolysis by using nuclear power.

Grey Hydrogen: Hydrogen produced through gasification of coal.

White Hydrogen: White hydrogen is found naturally in underground deposits of geological hydrogen. It's extracted through a process called fracking

Red Hydrogen: Hydrogen produced through the high-temperature catalytic splitting of water using nuclear power thermal as an energy source.

Gold Hydrogen:  Hydrogen produce from Biomass feedstock

Q.3 What is the major physical & chemical properties of Hydrogen?

Ans. Chemical/Thermodynamic Properties:

i. Mol. Wt: 2.016

ii. BP/MP int: -252.9/-259.13 deg.C.

iii. Critical temperature (Tc): -239.95 oC

iv. Critical pressure (Pc): 13.26 kg/cm2

v. Auto ignition temperature: 585 deg.C

vi. Flammability range in air (LEL/UEL): 4/ 74

vii. Net calorific value: 28555 Kcal/kg (2575 Kcal/Nm3)

viii. Gross Calorific value: 33889 kcal/kg.(3056 Kcal/Nm3)

Q.4 What the different types are of water Electrolyser's technology?

Ans. There are mainly four types of water electrolysers available:

1) Alkaline Water Electrolyser (AEL/AWE)

2) Proton Exchange Membrane Electrolyser (PEM)

3) Solid Oxide Electrolyser (SOEC)

4) Anion Exchange membrane Electrolyser (AEM)

Q.5 What is RPO?

Renewable Purchase Obligation (RPO) is the obligation mandated by Central/State Regulatory Commission and is applicable to Designated consumers (DCs) e.g Distribution Licensee (DISCOMS), Open Access Consumer and Captive consumer.

The Regulatory Commission in each State mandates a certain percentage of electricity generated / consumed through the above process should be from renewable sources. The DCs not generating / purchasing the required qty of RE power shall be required to meet the RPO by purchasing the equivalent amount of RECs from the power exchange like PXIL, IEX. One REC is equivalent to 1 MWh. It is market based instrument that certifies the bearer owns one MWh of electricity generated from renewable energy sources.

The government has recently mandated (vide MOP office order dtd. 22^nd July 2022) to include WPO (wind power obligation), HPO (Hydro power obligation) and other RPO (solar, non-solar, bio-mass etc.) as revised RPO for the new installation of power generation, CPP etc.

The RPO trajectory from 2022-2023 is as mentioned below:

Q.6 What is Net Zero?

'Net zero emissions'means cutting greenhouse gas emissions to as close to zero as possible, with any remaining emissions re-absorbed from the atmosphere. In other words, Carbon neutrality or Net-zero, refers to balancing anthropogenic greenhouse gas emissions with anthropogenic removal or offsetting of the greenhouse gases so that the net effect is zero emissions.

Q.7 What are the different types of carbon emissions?

Ans. Carbon emissions are divided into three categories: Scope-1, Scope-2 and Scope-3 emissions

i) Scope 1: Emissions from the production process from the combustion of fuel. This typically occurs within the plant/facility premises.

ii) Scope 2: Emission associated with the purchase of utilities. This is generally an emission outside the plant boundary.

iii) Scope 3: Indirect emissions are associated with the entire value chain, starting from equipment purchase, construction works, raw material sourcing and product dispatch

Q.8 What is 1G, 2G & 3G Ethanol?

1G: Ethanol produced from sugar/ lipid feed stocks, e.g; sugarcane, grains, molasses etc.

2G: Ethanol produced from Ligno-cellulosic feed stocks, e.g; rice straw, bamboo, bagasse etc.

3G: Ethanol produced from Algae and industrial/municipal waste gases.

Q.9 What are specification for BS-VI MS and BS-VI Diesel?

Ans. BS-VI MS specification

BS-VI Diesel:

Q.10 What is the Octane number and what is its significance?

Ans. This is an important test for rating the antiknock of the motor fuels. The knocking of the motor fuels in compared using blends of isooctane and normal Heptane in a single cylinder CFR engine. The rating can be done either by Research Method or Motor Method.

Octane number requirements of gasoline engines depend on their compression ratio and if the fuel meets the minimum requirements in respect of octane number it ensures trouble free operation

Q.11 What is the Cetane number and what is its significance?

Ans. Cetane number of diesel fuels is determined in a single cylinder CFR engine by comparing the ignition delay characteristics of the fuel with that of reference blends of known cetane number. The reference fuels used for this purpose are normal cetane (100 CN.) and Hepta Methyl Nonane *(15 CN.)

Cetane Number is the index of ignition quality of a fuel. High Cetane number fuel will facilitate easy starting of compression ignition engines and lessen engine roughness. In the absence of an engine, the Diesel index or the calculated Cetane Index will give an approximate idea of the ignition quality of the fuel. It can also be roughly assessed by the formula for fuels not containing ignition improvers. 

C.N. = 0.72 Diesel Index + 10.