Mercury emissions lowered by burning pellets

November 7, 2013, Washington, D.C. – A new report suggests
that the amount of mercury emissions from biomass fuel can vary depending on
the source and type of biomass burned.

The report, published in the American Chemical Society
journal Energy & Fuels, looked at
biomass used as fuel in rural China. According to the report, scientists are
now reporting that among dozens of sources of biomass, processed pellets burned
under realistic conditions in China emit relatively low levels of the
potentially harmful substance.

Xuejun Wang and colleagues explain that mercury is
associated with health problems, particularly in children. But reducing exposure
to mercury remains a huge challenge. In 2010 alone, coal-fired power plants,
gold mining, the burning of biomass for fuel and other sources generated about
2,000 tons of mercury emissions around the world. In China, biomass such as
plants and wood contributes to nearly a third of the energy used in the
nation’s rural areas.

To take steps to reduce mercury emissions, however,
researchers first need know how much of the substance comes from burning
different types of biomass. The problem is that previous estimates were based
on data measured in industrialized countries, which may not be accurate for
other locations. To get a clearer picture of what’s happening in China, Wang’s
team took measurements there with biomass sources and stoves that rural residents
actually use to cook and keep themselves warm.

They found that the levels of mercury released from burning
biomass in widely available stoves varied greatly, depending on the source.
Some of the highest levels of mercury came from burning certain wood species in
raw form, such as Chinaberry and Chinese pine. In comparison, biomass pellets
compressed from cornstalks and pine wood released lower levels of mercury.

“Biomass pellets can reduce mercury emissions compared with
the uncompressed raw materials,” the scientists conclude.