Commercialization of Adsorbed Natural Gas Technology
Akash Gupta
MBA Senior Year
Rajiv Gandhi Institute Of Petroleum
Technology, Raebareli, Uttar Pradesh

Fossil fuels, the foremost sources of energy for today's society, whether it be a developed or a developing nation all have its dependence and thus the need arises to look for the environment in accordance with the market as well. Natural Gas is a fossil fuel used for several of its uses these days being a clean source for energy and its nature of producing less pollution in comparison to other sources prevalent. There is this latest technology called Adsorbed Natural Gas Technology which follows the concepts of adsorbing the natural gas in special micro-porous material on room temperature thus allowing to refuel the tank with simple and cheap equipment . The ANG technology enables to store similar gas quantities as compressed natural gas under much lower pressure and thus decreases the filling station capital and operation cost besides natural gas end-user cost. With this technology the there comes the need for the development of the infrastructure to implement it, the method to install it and the requirement of market to cater it.

The fast pace with which the world is moving towards the energy sources those are cleaner and have low- carbon content dictates the story of the transformation that has taken place from the consumption of Diesel & Petrol to Natural Gas to Green Fuels. And this itself explains that the shift of Conventional to Unconventional fuel is not much smooth as it brings the challenges that needs time to be resolved. With present rate of consumption, these conventional fuel(fossil fuels) are near to their depletion and thus the shift is very much needed and thereby the consumption of Natural Gas (NG ) for major primary purposes is on the rise. Natural Gas being more advantageous than other hydrocarbons fuels offering greater reduction in Carbon monoxide, Nitrogen oxide, and Non-methane hydrocarbon emissions and is promisingly used as fuel for vehicle application, being cheaper than petrol and diesel. Presently, natural gas is used by compressing it under high pressure (17.2- 20.7 MPa) in order be stored in a substantial amount, called as Compressed Natural Gas (CNG). However, these high-pressure leads to several problems related to the storage system; cylinder corrosion, possibility of explosive leak of the gas, etc., which becomes the main cause for NG not to be used for vehicular application. But there is this Adsorbed Natural Gas (ANG) Technology, which presents us with whole new perspective to store the natural gas in a lot more safe and convenient manner.

Adsorbed Natural Gas technology stores natural gas over these materials that act a sponge to adsorb the natural gas. It allows substantially higher concentrations of gas to be stored, without requiring any refrigeration methods or equipment. It takes place at relatively low pressure around 3.5 MPa, achievable by single stage compression and can provide same capacity as compared to CNG. Specifically, for the vehicular application of this technique, maximum gas storage density becomes the utmost requirement to achieve the desired level of mileage range.

For bulk storage of gas through this method the viability depends upon:
  • Selection Adsorbing material
  • Storage per volume stored (v/v)
  • Density of the Adsorbent
  • Cost of Material
  • Amount of material to be used
  • Size of the container (in which the adsorbing substance will be kept)
  • Activated Carbon, made from the Coconut shells or Peach stones, are subjected to either chemical impregnation followed by heating or are first pyrolyzed to carbon and then subjected to steam treatment. Some other adsorbent could include Graphene, Metal-oxide frameworks, etc. The microscopic physical proper ties and electro-chemical proper ties of the adsorbent enable 10 to 100 times the amount of gas to be stored in a given volume of pressure compared to the conventional compressed gas storage (on a given surface area).
    Generally, a good adsorbent should has following properties:
    • A porous structure with high surface are to volume and weight ratio
    • Physically and Chemically stable
    • A relatively good conductor of heat for adsorption and desorption cycle
    • Economical to manufacture
    • Easily recycled

    The process involved in the whole procedure is, adding up of the NG to a storage system, called adsorption (exothermic process), withdrawing of the gas from the storage system, called as desorption (endothermic process), which is as the pressure begins to drop in the system, the methane molecules are released from the sur face of the adsorbent material into the gaseous state. There are thermal changes involved while the adsorption and desorption processes are going which also affects the discharge rate of the gas.

    When it comes to the commercialization of any technology the parameters used to evaluate are to be taken care of and likewise, the evaluation of the per formance of various adsorbents is based upon the amount of gas retained in the adsorbent at the end of a desorption cycle. The absolute uptake is the total amount of gas adsorbed on the initial adsorption cycle, noted as "V/V" . the working capacity denotes the gas delivered on a desorption cycle. There are near to no technical obstacles prohibiting the construction of an ANG storage system, as all the components are already in use for CNG applications, with some technical changes required for the newer technology .

    There will be a paradigm shift in terms of the benefits that could be incurred on implementing ANG technology (low pressure on-board natural gas), like:
    • Enables fueling of the NG on private/individual basis due to low compression requirements
    • Comfortable low weight storage tank
    • Lowers the cost of every fuel consumed (petrol/diesel)
    • 75% reduction in carbon monoxide emissions*
    • 55% reduction in volatile organic compounds*
    • 50% reduction in nitrogen oxide emissions*
    • Up to 30% reduction I carbon dioxide emissions*
    (* Source: Southern California Gas Company and the 2008 TIAX, LLC Report Well-To-Wheels, prepared for the California Energy Commission)

    Recently, several organizations are joining hands to bring forward this technology and to commercialize it in a more adaptable manner like, Ingenvity had participated in a corporate coalition with Adsorbed Natural Gas Products, Inc., United Technology Research Center, and Worthington Industries (U.S.A based firms)

    # Today the society is trying to help the environment in every way possible and ANG technology do possess some hidden benefits for the world to explore. Innovation, Development and Implementation are the 3 pillars that enable any technology to cater the society, so let us try to fill-in the gaps to reap fruits from this technology.