By: Ankur Bordoloi, Srikant Nanoti & team,
CSIR-Indian Institute of Petroleum, Dehradun, IIT Roorkee and Bharat Petroleum
The search for an alternative to carbon-based fuel for automobiles has been going on for a long time and a large number of options are being researched. But the introduction of a new automobile fuel could take several years because of issues like redesigning of engines and re-establishment of distribution networks. So in the near future, we seem to have reconciled to the use of petroleum products, at least in India and in many other parts of the world.
We have now zeroed down on a compound called Dimethyl ether, or DME, which too has carbon. It can be blended with conventional fuel to improve its combustion properties or it can be used as an alternative fuel itself. DME is not naturally occurring and needs to be prepared from natural gas. India does not have enough natural gas and much of what we have lies in small pockets of reservoirs that are not economical to exploit. Setting up large infrastructure like pipelines to transport this gas to the refineries is not worth the investment because the deposits would may run dry with time. But if we are able to develop a method of converting the gas into DME at the source of the reservoir itself, it may become economically viable to transport and use it as a fuel.
This is our goal. We are trying to design “modular reactors” that can sit at the back of trucks and can travel right to the mouth of the reservoir. The gas extracted from the reservoir can be directly pumped into the reactor which will convert it into liquid DME after a three-step chemical process. Natural gas is converted into Syngas, which is a mixture of carbon monoxide and hydrogen. This is then converted into methanol, which is further converted to DME. Designing this entire system into one compact unit is the biggest challenge of our three-year-old project. We are also looking at other components, including the implementation of DME utilisation in vehicles and engines, which is being done at CSIR-IIP Dehradun. Our study showed that DME has the potential to be used as a partial substitute to conventional fuels in diesel and petrol engines. DME has superior combustion properties compared to diesel fuel, as it has advantages such as high cetane number and absence of carbon-carbon bond and, therefore, has potential to reduce pollutants in diesel engines.
We are collaborating very closely with three Australian institutions (CSIRO, UoM & RMIT) on this project and they are helping us with the fabrication of the modular reactors and many other crucial tasks. Besides, producing DME in this manner will reduce our dependence on import of natural gas by utilising our own deposits that otherwise would have remained unutilised.
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