Use of alternative-fuels in cement
kilns debated
The use of alternative fuels in cement kilns continues
to spark debate among industry, civil society and nongovernmental
organizations.
Cement production is characterized by an extremely
high-temperature combustion process, most commonly using fuels such
as coal, natural gas and other nonrenewable resources.
In the drive towards sustainability, cement manufacturers
have recognized their responsibility to manage the environmental
impact associated with the manufacture of their product and, as
part of this commitment, the industry is pursuing an ongoing strategy
of reducing nonrenewable fuel use through the adoption of alternative
fuels, also referred to as waste-derived fuels.
The use of alternative fuels in cement kilns is
widespread and various countries, including the UK, the Netherlands,
Germany, Sweden and the United States have cement companies that
use alternative fuels. Natal Portland Cement (NPC) operations manager
Laurence Stevens comments, “The cement industry has clearly
embarked on a trend toward applying the principles of the so-called
industrial ecology, based on using by-products of other industries
as raw materials and fuel.
“This trend was inspired by the self-containment
of most natural ecosystems that normally produce waste.” However,
the term ‘alternative fuel’ is the cause of some contention.
According to Groundwork director Bobby Peek, the
debate surrounding alternative fuel use is “being fudged by
cement companies”.
“Cement companies are proposing to burn
hazardous waste. But by attempting to create a debate that hazardous
waste is an alternative fuel, this could, in turn, result in hazardous
waste being reclassified as a fuel which could potentially lead
to the importation of hazardous waste into South Africa, a practice
that is forbidden by the Basel Convention and Bamako Convention,”
elaborates Peek.
The technical and environmental review published
by the European Cement Association refers to alternative fuel materials
as those that are rich in energy and can be used to replace coal
or gas, provided they do not contain harmful substances.
Holcim South Africa alternative fuels manager,
Johan Schoonraad argues that a common misconception about alternative
fuel use is that all alternative fuel, in the categories earmarked,
are suitable; instead, alternative fuels are based on very specific
waste streams.
“We have strict rules about what materials
can and cannot be used. In addition, we have a ‘no-go’
list, which is strictly adhered to, that prohibits the use of untreated
medical waste, radioactive waste, explosives, high-cyanide wastes,
asbestos-containing wastes, bio-hazardous wastes, electronic wastes
and unsorted municipal garbage, among others.”
Holcim South Africa cement operations director,
Dr. Stephan Olivier continues, “We are not becoming waste
collectors. The material required for our operations must be of
the correct volume and chemical composition.”
To assist in the sourcing and collection of these
specific waste streams, Holcim has formed a joint-venture company
with Enviroserve, to oversee this operation.
In addition, the company is in talks with other
waste producers and petrochemicals companies. However, Earthlife
Africa director Richard Worthington believes that the use of waste
as alternative fuel serves to entrench the current unsustainable
waste-management and waste-generation practices, as he explains
that, in many cases, waste could be designed out of industrial systems.
Worthington believes that the use of waste material
in cement kilns is, at best, a dressed-up form of disposal, despite
industry arguments that cement producers are reusing waste and are
part of the waste hierarchy (minimize, reduce, reuse and recycle).
In the case of Holcim, Worthington comments that
many of the materials considered by the company as alternative fuels
are waste streams that it should just not be generating.
“In some cases, there are products we need
to replace, particularly a number of petrochemical products.”
These materials include tires, rubber, paper, sludge, plastics,
solvents and industrial tars.
“Kilns are very expensive and cannot be
put at risk. As a result, we, at Holcim, are incredibly careful
about what we place in the kilns.
“In addition to large volumes we also need
materials of which the chemistry will remain constant,” says
Schoonraad. Schoonrad explains Holcim’s policy: “Only
if a material does not lend itself to recycling, do we consider
using it.”
Tires are a classic example. “The rubber
industry is able to recycle about 40% of used tires at the most;
the remaining 60% are probably subjected to incineration or assigned
to landfill sites adding to the burgeoning issue of waste disposal
globally,” indicates Schoonraad.
Peek, however, disagrees. “There are various
acceptable ways of dealing with waste tires globally that do not
result in incineration – one of which is using tires to mix
with tar for road surfaces.” Consequently, the use of cement
kilns, in terms of community waste-management options as effective
alternatives for the disposal of selected waste materials when compared
to conventional disposal techniques, are championed by cement manufacturers.
Stevens also emphasizes the use of kilns to assist
society in safely disposing of waste, after approval by the waste-management
hierarchy.
“This service will reduce the size of landfills;
create a new waste market, new companies and job opportunities.
“In less developed countries or regions,
it has the added bonus of creating waste management infrastructure
and promoting economic and social progress,” says Stevens.
Peek, however, insists that burning hazardous
waste is not a suitable way to deal with such material.
“Also, the burning of chlorinated waste
may lead to the formation of dioxins and other persistent chemicals
which are proven carcinogens,” says Peek. Schoonraad concedes
that a poorly-run combustion process does have the potential to
release some dioxins but is quick to point out that cement kilns
have rigidly-controlled operational conditions to ensure quality
of cement.
Schoonraad points out the stringency of Holcim’s
national and international standards, which include the installation
of monitoring equipment, annual testing, free flow of information
and a strict internal focus on emission control.
Cement kilns are permitted and regulated by government
as cement-manufacturing facilities and, as such, they do not have
to meet the same stringent standards of performance and emissions
limits as “hazardous-waste incinerators to safeguard human
health”.
However, Stevens notes that “the nature
of the requirements for cement-kiln design to enable production
of clinker, results in a thermal processing device which far exceeds
the legislated requirements for incinerators”.
According to Peek and Worthington, the benefits
of using alternative fuels in cement kilns are mostly to do with
cost cutting and efficiency. “The benefits to cement companies
are that they make profit because of the high fuel costs involved
in making cement.
Regardless, both NPC and Holcim believe the application
of alternative fuels is in line with responsible practices and sustainable
development.
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