British Thermal Unit (Btu) is a measurement of thermal energy.  It is equal to the quantity of heat required to increase the temperature of 1 pound (lb) of water at sea level by 1°F.

Boiling Water Reactor (BWR) a light-water nuclear reactor to produce electricity and is designed to operate on a closed water-steam cycle. It is similar to the pressurised water reactor (PWR), except that in a BWR the steam which goes to the turbine is generated in the reactor core instead of in heat exchanger or a steam generator.

Combined Heat and Power (CHP) is an efficient technology that simultaneously uses heat and electricity. Normally heat is lost during the power generation, but CHP captures the thermal energy and uses it further for various applications. CHP is also known as cogeneration.

CNG stands for compressed natural gas. It is made up of 93.05% methane and the first product which is separated during the distillation process. It is made through compressing natural gas down to less than 1% of its volume. CNG is compressed between 200 and 300 bars.

Density is a measure of mass per unit of volume and can be calculated by dividing mass by volume. The higher the density of a product, the high would be its mass per volume. Mass measures the amount of matter in an object while volume measures the amount of space the object possesses.

Exothermic Reactions are processes that result in releasing energy, normally in the form of heat or light. Exothermic reactions can be in different forms such as combustion, neutralisation or thermite. For example, the reaction of hydrogen and oxygen in a combustion chamber create superheated steam.  The opposite of exothermic reaction is an endothermic reaction which actually requires heat or light to occur. An example of an endothermic reaction is the melting of ice cubes, which uses heat.

Fuel cell (FC) is an electrochemical cell that utilises the chemical energy of hydrogen or another fuel (which can be liquid) to generate electricity. If a fuel cell uses hydrogen as fuel, then electricity, water, and heat are the only products. Fuel cells are categorised mainly by the types of electrolyte they use. The classification also determines various things about the fuel cell, such as the type of electrochemical reactions that are supposed to occur in the cell, the type of catalysts needed, the temperature range for cell operations, and the type of fuel required. Some types of fuel cells are: Alkaline Fuel Cells (AFC), Direct Methanol, Fuel Cells (DMFC), Molten Carbonate Fuel Cells (MCFC), Phosphoric Acid Fuel Cells (PAFC), Polymeric Electrolyte, Membrane Fuel Cells (PEMFC), Reversible Fuel Cells (RFC) and Solid Oxide Fuel Cells (SOFC)

H2 or dihydrogen is a gas and is made up when two hydrogen atoms bond together and become hydrogen molecule. That is why H2 is also called molecular hydrogen. H2 consists of two protons and two electrons.

Liquefied Hydrogen (LH2) stands for hydrogen in liquid form. Hydrogen can exist in a liquid state, but that requires frigid temperatures of −252.87 ºC (-423 ºF). The transport of LH2 is considered one of the effective options.

Liquid Organic Hydrogen Carrier (LOHC) is an organic substance in liquid or semi-solid states that store hydrogen by catalytic hydrogenation and dehydrogenation processes over multiple cycles. Hydrogen is stored inside the liquid hydrogen carriers via a catalytic reaction. The liquid has a low viscosity which seems like water, and once hydrogenation, the viscosity increases with the material resembles honey. LOHC is also flame-retardant, making it ideal for safe transportation.

LNG stands for liquefied natural gas. It is a liquid form of natural gas and produced through liquefaction. It is a process where natural gas is cooled at low temperatures (-162 ºC) at ambient pressure until it turns into a liquid. The volume of gas is reduced by approximately 600 times.

LPG stands for liquefied petroleum gas. It is a liquefied gas that is a by-product produced during the petroleum refining process. It is made of hydrocarbons or mixtures of hydrocarbons such as propane, propylene, normal butane and butylenes. It is stored under pressure to keep the gas in liquid form. LPG is a mixture of 48% propane, 50% butane and 2% pentane.

PEM stands for ‘polymer electrolyte membrane’. The acronym also refers to ‘proton-exchange membrane’. The first term is used to describe the function of the membrane while the latter form is used to highlight the membrane’s material property. Both terms are often used interchangeably for a class of fuel cells that consist of a solid polymer membrane layer used as an electrolyte, allowing protons between the electrodes. Protons are exported from anode to the cathode side in the temperature range of 60 ºC -100 ºC.

Pressure Swing Adsorption (PSA) is a special method for purifying gases and used to separate a single gas from a gas mixture.

Psi stands for pounds per square inch and is often used to measure gasses’ pressure. Psi is the pressure resulting from a force of one pound-force applied to an area of one square inch. 1 psi = 6,894.76 Pascals