Chimi Dema

Given that the country generates 215 metric tonnes of municipal waste (MW) every day, about 50 tonnes of refuse-derived fuel (RDF) could be produced from sorted waste.

This could replace 25 tonnes of coal in resource-intensive cement industry as an alternative fuel and contribute to 5 percent of thermal substitution rates.

The estimate for co-processing of waste in local cement industries was made by experts from Norway and India, members of municipalities, local cement industries and governmental institutions during a consultation workshop held in the capital on November 29. 

Co-processing in resource-intensive industries involves the use of waste in manufacturing processes for energy and resource recovery, reducing the use of conventional fuels and raw materials through substitution.

“Co-processing of wastes in properly controlled cement kilns provides energy and materials recovery while cement is being produced, offering an environmentally sound recovery option for many waste materials,” an official with the National Environment Commission (NEC) said.

In Bhutan, the three integrated cement plants, Dungsam Cement, Penden Cement, and Lhaki Cement produce clinker using rotary kilns with dry process and consume an average of 500 tonnes of coal a day.

Generally, energy costs of fuel and electricity represent 40 percent of cement manufacturing costs. The Dungsam Cement produces 1.3 million tonnes of cement annually.

The replacement of fossil fuels by waste also gives the opportunity to manage industry in an environmental sound manner, avoiding emissions of greenhouse gases.

“Cement production is accountable for 6 percent of man-made carbon dioxide where 40 percent comes from the combustion of coal and 60 percent from the calcination of limestone,” said Kare Helge (PhD), Chief Scientist and Special Advisor with SINTEF.

He said that controlled co-processing could provide practical, cost-effective and integrated waste treatment preferred options to landfill and incineration.

Today, about 75 percent of coal is replaced by various waste in the Norwegian cement industry.

In India, the number of cement plants using co-processing has grown from 12 to 59 in a span of six years. The average 4 percent of TSR in 59 industries accounts for 1.6 million(M) tonnes of alternative fuel use, saving 1.1M tonnes of coal.

However, not all wastes are suitable for co-processing. Only waste of known composition, energy and mineral value is suitable for co-processing in cement kilns according to the experts.

Incentives through carbon credits, green rating and tax subsidy were a few opportunities identified in co-processing of cement industries.

However, in Bhutan, low volume of waste, distance between waste source and cement industries, low production capacity, lack of incentives, and limited technical capacity and guidelines were limitations identified by participants.

Participants called for setting up of trail, building capacity for stakeholders, adopting segregation incentive mechanism and developing infrastructures to initiate co-processing of cement industries that can also help achieve zero waste society by 2030.

The Chief Environment Officer at waste management division, NEC, Thinley Dorji, said while there were limitations, the agencies could still attempt to initiate. “We can continue studying the feasibility in the next few consultation workshops.”

To discuss opportunities and limitations of co-processing in resource-intensive industries in the country, the NEC in collaboration with United Nation Environment Programme in India and SINTEF in Norway conducted a day-long seminar.