As per estimates, the annual fly ash generation in our country in 2009-10 was about 200 million tonnes; fly ash recycled is about 30%, i.e about 60 million tonnes. Out of this the cement industry consumes around 38-40 million tonnes which is above 70% of the recycled ash. Hence, there is still a huge surplus of 140 million tonnes which is being disposed off as slurry in the ponds.
Another approximately 128,000 MW of new power generation capacity is expected to come up in the country within three-four years. Out of this major portion of around 75% would come in form of thermal power. Estimated generation of fly ash till 2015 would be 300 million tonnes, which again would pose a serious problem of disposal. The major consumer of fly ash is the cement industry only, while some small quantities are used for making fly ash bricks, landfill etc.
Disposal and market sources
In the past, fly ash produced from coal combustion was simply entrained in flue gases and dispersed into the atmosphere. This created environmental and health concerns that prompted laws which have reduced fly ash emissions to less than 1% of ash produced. Further recycling of fly ash has become an increasing concern in recent years due to increasing landfill costs and current interest in sustainable development.
Fly ash, like soil, contains trace concentrations of many heavy metals that are known to be detrimental to health in sufficient quantities. These include nickel, vanadium, arsenic, beryllium, cadmium, barium, chromium, copper, molybdenum, zinc, lead, selenium, uranium, thorium, and radium. Though these elements are found in extremely low concentrations in fly ash, their mere presence has prompted some to sound alarm.
Fly Ash Utilisation Programme (FAUP), a Technology Project in Mission Mode of Government of India commissioned during 1994, is a joint activity of Department of Science & Technology (DST), Ministry of Power (MOP) and Ministry of Environment & Forests (MOEF), wherein Department of Science & Technology is the nodal agency and Technology Information, Forecasting and Assessment Council (TIFAC) is the implementing agency.
The mission was converted into a programme called Fly Ash Utilization Programme (FAUP) in 2002. In 2007, the programme was shifted to Dept. of Science and Technology (DST).
With the Ministry of Environment and Forests (MoEF) permitting the sale of fly ash since November 2009, there is greater interest among power generators to exploit fly ash as a commercial resource. NTPC, for example, has started trading of fly ash through its subsidiary, NTPC Vidyut Vyapar Nigam Limited, with a target of 4.5 million tonnes fly ash trading by 2013-14.
There are many barriers and challenges to 100 per cent fly ash utilisation. Until the MoEF notification in November 2009, there was no commercial orientation for fly ash, which meant potential users did not have enforceable contracts for consistent quality and regular supply of fly ash. Standard specifications, strategies for better management of various streams of fly ash, technologies for high efficiency electrostatic precipitators that maximise fly ash collection, logistics of storage and transportation, etc. are a few other areas that need attention.