Tuesday, March 6, 2012
Hydrogen assisted combustion
We have been using fossil fuels like diesel, petrol and natural gas for power generation and transportation from the time of industrial revolution. The basic fuel and the combustion technology are practically the same with efficiencies less than 40%. In fact we have become very complacent with both the fuel and the combustion technology and there were no major research and development on both the above issues. In fact we became completely dependent on these two issues and there was no substantial breakthrough either in substituting the fossil fuel or in the combustion technology. The basic reason behind this situation can be attributed to the discovery of electromagnestism, which opened the way for electricity generation as well as transportation. In both these industries, the key component is the motor which provided a rotary motion. This rotary motion generates electricity in turbines and such motion is created by combustion of a fuel, which is invariably a fossil fuel. We have been carrying on this for few decades before the emission of greenhouse started rising abnormally and became an issue. We are now at cross roads wondering what the future holds for the world. Is it possible to carry on the business as usual or look for an alternative source of energy? We started looking at various sources of energy as an alternative. Any alternative energy source should meet two critical parameters namely the lower or no carbon emission and sustainability. Low carbon can be achieved by few methods. The immediate option is to maximize the energy efficiency of existing systems so that for the given input of fuel the output is much higher than what we have achieved all these years. But this increase in efficiency should be substantial in order to achieve the emission levels of greenhouse suggested by the UN panel on climate change. The second option will be to switch over to different fuels with less carbon emission e.g., coal fired power plants switching over to gas fired power plants using combined cycle. Retrofitting organic Rankin cycle as a bottoming for steam turbines to squeeze out some extra energy. Decentralizing the power plants in a phased manner in favor of distributed energy systems where gas, instead of electricity, can be supplied to individual industries, to generate their own power using CHP process. All these measures can help reduce the emission level but our dependency on fossil fuel will still continue. W can look at a completely different fuel source and new technology for power generation and transportation. If we examine carefully there are not many alternative fuel sources except Hydrogen that could meet these parameters. We are also trying to develop bio fuels. But biofuels are also organic chemicals with carbon backbone which will generate greenhouse emission. Moreover bio fuel sources such as palm oil, corn are also food sources. There is an indiscriminate deforestation and plantation of palm trees in tropical countries like Malaysis, Indonesia and PNG. The focus is now shifting to carbon based organic compounds like biofuel and biogas. This will create a situation where food crops will be substituted with energy crops creating food shortage.But the carbon dioxide level in the atmosphere may not be reduced drastically by these methods. We need to develop an energy source which does not emit any carbon emission and at the same time we should be able to use existing technology to the possible extent. Only Hydrogen can meet these requirements. In the current situation it is impossible to substitute fossil fuels in a short span of time. We can reduce fossil fuels by blending with Hydrogen to the maximum extent possible so that we can achieve two objectives. We can reduce the carbon emission and at the same we can deploy Hydrogen as a blended fuel with fossil fuel rather than pure Hydrogen. Since Hydrogen is a very light gas and readily form an explosive mixture with oxygen, this opens up a new opportunity to develop Hydrogen assisted combustion process in power generation as well as in transportation. It will be easier to handle a mixture of natural gas and Hydrogen for combustion in Gas turbine, or spark ignited reciprocating engines, as well as, gasoline combustion engines in cars. This will also gives us an opportunity to develop advanced and competitive systems like Fuel cell as an alternative technology for combustion process in due course of time. The hydrogen assisted combustion technology is much easier, faster and economical and at the same time reduce the greenhouse emission to an accepted level. But the source of such Hydrogen cannot be natural gas but only renewable sources. The renewable technologies such as solar, wind, geothermal, OTEC (ocean thermal energy conversion) should generate renewable Hydrogen. This is the key for sustainability as well as for greenhouse gas mitigation. These two benefits are too attractive to ignore and it is time we move from total fossil fuel to Hydrogen blended fossil fuel. The blended fuel along with the energy efficiency measures suggested above should go hand in hand, so that we may get over this turbulent period of financial crisis and global warming. It is also possible that Hydrogen assisted combustion be adopted for coal fired power plants by simply firing coal slurry, finely powdered coal blended with water and conveyed pneumatically for firing boilers and also for gasification process to generate syngas for IGCC (Integrated gasification and combined cycle) applications. Syngas production will be critical in the near future for a smoother transition from fossil economy to Hydrogen economy irrespective of the route we adopt.