Against the resistance of Germany, the EU lowers the upper limit for nitrogen oxide emissions from brown coal power plants.
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The Weisweiler brown coal power station is one of the industrial
plants with the highest pollutant emissions throughout Europe.
(Photo: panthermedia.net/Werner Nick)
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For more than 3,000 smaller and larger combustion plants, the EU is now
redefining the state of the art.Experts from the Member States, the
European Commission, as well as industrial and environmental associations
had been struggling to achieve the best available technologies (BAT).
The EU reference number now largely agreed with the BAT reference
document, albeit with minor changes. The emission of particulate matter,
sulfur dioxide, nitrogen oxides (NOx) and mercury will be stricter in four
years.
"The German-led brown coal lobbies were overruled", reveals Christian
Schaible from the European Environment Bureau (EEB). This lobby also
included Bulgaria, Finland, Poland, Romania, Slovakia, the Czech Republic
and Hungary.
"The vote was very short," adds Schaible. A qualified majority of 65% was
necessary. These reached 20 EU countries with a voting weight of 65.14% so
grade. Before this, Greece was agreed with the package with a vote weight
of 2.11%, after it was decided that the new BAT requirements for the use
of heavy fuel in diesel engines on islands would only apply from 2030
onwards (by comparison, Germany's weight of votes) 16.06%).
The reference document was controversial. Thus, the Federal Government
interfered with the values for NOx emissions from brown coal power
plants (300 MW heat output). In normal operation, an upper limit of 200 mg
NOx / m³ was used in annual mean. In the future, there should be a range
of 85 mg to 175 mg NOx / m³.
However, the Federal Government considers the upper limit value to be not
appropriate and instead proposed 190 mg / m³. "We have relied on the
scientific assessment of the Federal Environmental Agency," says Stephan
Gabriel Haufe, spokesman for the Federal Environment Ministry.
But a combination of measures is not prescribed, emphasizes UBA specialist
Rolf Beckers. "The application of only combustion technology measures is
also regarded as BAT". A recent UBA survey in the federal states in which
lignite-fired power plants are operated showed that the annual power
plants release between 160 mg and 195 mg NOx / m³ with firing technology
optimization.
"Only four of 28 German lignite blocks reliably emit 175 mg / m³," says
Beckers. There are two in each case at the locations Lippendorf in Saxony
and Schwarze Pumpe in Brandenburg. But also brown coal power plants in
Greece have been emitting less than 175 mg / m³ since 2010, Schaible adds.
He considers the derivation of the 175 mg value to be appropriate. And he
has no objection to a combination of measures.
"The 175 mg can be safely met with SNCR technology," said Bernd von der
Heide, Managing Director of the Essen company Mehldau & Steinfath
Umwelttechnik, as well as Wolfgang Schüttenhelm, responsible for business
development and technology at ERC Technik in Buchholz.Both companies are
using this technology in waste incineration and biomass plants as well as
in Eastern European lignite and brown coal power plants. The NOx emissions
can thus be reduced by 30% to 50%, in addition to measures in terms of
combustion technology.
For example, ERC has retrofitted Block 3 of the world's largest brown coal
power plant in Bełchatóv in Poland with an SNCR facility in 2016. "Since
then, the valid NOx limit value of 200 mg / m³ has fallen below 50 mg /
m³," emphasizes Schüttenhelm.
SNCR is not a marvel, says Anlagenbauer von der Heide: "We arrange several
lances around the furnace in the boiler, through which we can reduce the
amount of NOx in the flue-reducing agent." These are chemicals which,
under the action of heat, ammonia (NH3) Which reacts with NOx to form
nitrogen and water vapor.
Important is the temperature, supplemented by the heath. The reaction of
NH3 with NOx proceeds favorably between 950 ° C and 1030 ° C. If, however,
it becomes hotter than 1200 ° C in the furnace, the reducing agent itself
burns into nitrogen oxides. This can happen in many power stations at full
load. "We then cool the flue gas by selectively sucking in the lance."
But the political discussion is not yet finished. The tussle continues.
Now, exceptions and the upcoming revision of the large combustion plant
regulation are being disputed.
"In the interests of proper implementation, licensing authorities may
grant exemptions in individual cases", Haufe explains. They may permit
slightly higher annual emissions if the 175 mg upper limit can only be met
with disproportionate expenditure.
However, the UBA expects only minor improvements in air quality. "In the
brown coal power plant, the NOx emissions would drop by an average of 10
mg / m³," says Beckers. This corresponds to a reduction in the annual
freight by 5% - and thus by a good 4500 t. The total NOx cargo of 1.22
million tonnes from all sources would thus drop by less than 0.4%. The
load with nitrogen dioxide (NO2) in inner cities would not drop
measurably.
However, the release of nitric oxides would decline significantly, the
Federal Government did not follow the 175 mg target, but the technical
possibilities, Schaible said. "We demand a NOx annual limit of max. 85 mg
/ m³ for power stations that will still run until 2027. "To do this, the
plants would have to catalyze their flue gas catalytically - as is already
the case today with coal-fired power plants. "If a power plant block goes
off the grid by 2024, Schaible would accept an upper limit of 150 mg / m³,
which is achievable with the cheaper SNCR variant.
In addition, Schaible considers the retrofitting with SNCR or SCR as
justifiable. "Both economically worthwhile in just a few years." He points
to figures from the European Environment Agency in Copenhagen: every ton
of saved NOx emissions reduces health costs and damage to the environment
of up to € 19,000.
Article: VDI
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