Arunn's Notebook

IGCC Technology and Indian Energy Insecurity

Arunn Narasimhan

Some questions and discussion on the Way forward, the recent Hindu editorial on IGCC technology for India. It correctly writes IGCC is the way to go in the future. But glosses over on pertinent issues on energy security.

Before going into the editorial, a summary on IGCC technology. IGCC stands for Integrated Gasification Combined Cycle. This is a technology which tries to increase the energy utility of a conventional coal fired power plant. Instead of being combusted as done in conventional pulverized coal fired power plants, in IGCC coal is gasified and converted into a synthetic gas (or syngas). This high temperature syngas is used to run gas turbines that generate power. The high temperature in the gasification and the high temperature syngas coming out of the gas turbine are further utilized to heat water and generate steam, which is used to run steam turbines to generate additional power. So IGCC is a combined cycle plant. See the schematic below for clarification.

[image courtesy Energy Northwest]

Now for discussing the Hindu editorial. It starts with an encouraging news

Last week, an agreement was signed between the BHEL and Andhra Padesh Power Generation Corporation to set up a 125 MW power plant at Vijayawada using IGCC (Integrated Gasification Combined Cycle) technology. Employed on a trial basis in India over the past two decades, IGCC has now been scaled up and put to commercial use.

and goes on to enunciate some advantages

What puts IGCC above the conventional pulverised coal technology is its thermal efficiency. At present it is about 45 per cent efficient but could go up to 60 per cent. This is a substantial improvement over the 35 per cent efficiency of pulverised coal plants. For every one percentage point rise in thermal efficiency, there would be a reduction of about two to three points in greenhouse gas emissions. These factors will also help IGCC plant qualify for earning carbon credits.

It is good that BHEL is trying out this demonstration IGCC plant. But there are some issues. The IGCC technology I presume is entirely borrowed from the USA. Nothing wrong. That is what we have been doing for the last many decades as far as technology is concerned. We wait for technology to mature in another part of the World and buy into it lock stock and barrel and claim we are using advanced technology. If this is true with IGCC then the technology should use a gasifier (see above schematic) that is fit for low ash coal - as available in the USA. Low ash coal doesn't generate much particulate content when gasified and so the generated syngas can be sent directly into the gas turbine, without causing much damage. This is not yet true with high ash coal.

For instance, how is the gasifier for high ash coal to be designed such that at high gasification temperatures (around 1200 Celcius) the ash content could be prevented from forming slag. Let us say, ash doesn't slag. Even then, how reliable is a filter we have designed for removing these particulates in the syngas before sending it to the gas turbine unit? As far as I have heard, there is a porous filter designed in the USA that can handle particulates at around 650 Celsius. But that was designed for some other purpose. Remember, US based IGCC units use low ash coal, which have a good gasifier design to control the chemical reactions and also doesn't require filtration (very less particulates) before being sent to the gas turbine unit. Even if BHEL is going to use this kind of filters before the IGCC gas turbine unit, it should bring down the syngas temperature from around 1200 C to around 650 C before using the filter. This would reduce the thermal efficiency of the IGCC.

I am not sure what the proposed 125 MW plant by BHEL will be using to counter these issues. One media report suggests they are going to test Indian high ash coal. This would be great but I hope by 2011 (commissioning time) it doesn't come down to using imported low ash coal (imported from Philippines with ~ 4 percent ash) for demonstration. Nothing wrong, but that is not energy security. We should indigenously come up with a gasifier technology for using Indian high ash coal with the IGCC.

Moving on, yes, IGCC is an improvement over pulverised coal plants in some ways. It also fares better in terms of less pollution. But the mentioned thermal efficiency of 60 percent is yet to be demonstrated any where in a commercially viable situation. In fact, the 45 percent mentioned is for low ash coal, that too on paper. American paper. I am no energy expert, but I have excellent colleagues who are. They convince me with their calculation that IGCC probably can reach using present technology to 42 percent efficiency, with low ash coal. This is slightly more than what our proven pulverized coal fired units are capable of (38 percent).

There is a mention in the editorial further about the Indian high ash coal

The high ash content of Indian coal has been blamed for the higher emission of suspended particulate matter by thermal plants. But IGCC, in comparison with a conventional plant, promises to remove, independent of the coal type, 99 per cent of the sulphur compounds, 90 per cent of Nox and 35 per cent of CO2. It is also low on water consumption.

This misses the point. SOx and NOx and particulates are already taken care of by flu gas desulpherization (my BTech. project), controlling furnace temperatures and electrostatic precipitators respectively. These will still work with IGCC and BHEL and NTPC are past masters in using these. But the real problem is not with the pollutants totally (although there is one - read below), but as I explained above, in the non-availability of a good reliable IGCC gasifier technology for high ash coal.

Pollutant removal capability is true for IGCC. But once you remove these pollutants, what is the economically viable option of removing them in India? For instance as recent as Nov 2007

A Washington state regulatory board on Tuesday advised the governor to reject plans for Energy Northwest’s proposed 680-megawatt integrated gasification combined-cycle (IGCC) power plant because plans do not specify how carbon dioxide emissions would be sequestered underground

If things are that stringent in the USA for proper disposal of the IGCC pollutants, how can India(ns) find a quick fix solution for a technology (IGCC) that they are any way importing from the USA? Usually the sulfur content removed is turned out as a commercial use in the USA. How are we (India) going to handle this? Hydogen is also produced in the IGCC products. This the USA very much want and is one of the reason I suspect it encourages IGCC. Are we (India) in a position to do the same. Produce hydrogen and do what? Is there any plan for using it in fuel cells and related transportation energy needs? Of course, all these questions are not directed at the above editorial but I thought were relevant to the IGCC technology. Energy security needs to think and act holistic.

To summarize, IGCC is a nice technology that, as usual, we can import. But it has technological problems to be tackled in its gasifier, if high ash coal, which is available in India, has to be used. If high ash coal cannot be used in the near future, using IGCC would require India to import low ash coal. Importing technology (IGCC) and also the raw materials (low ash coal) is not energy security.

In this regard, the suggestion in June 2007 by the Asean Clean Energy Forum that

IGCC technology is in the early demonstration phase and is more expensive than competing alternatives. Entrained IGCC technologies are suitable for low-ash coals. High-ash coals, such as those in India, would require fluidized-bed gasification processes.

is a worthy alternative.

IGCC is welcome provided it could be done indigenously by burning Indian high ash in their gasifiers and still achieving their touted 45 percent (60 is a joke as such) efficiency. Else we can rely on the existing pulverized coal technology (in which our BHEL and NTPC are past masters to squeeze every bit of energy) for India to achieve coal energy security.

© Arunn Narasimhan | Original version written ~ 2009 | Last revision on Apr 01, 2012

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