Reducing Methane Emissions with sustainable recovery compressors

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REDUCING
METHANE
EMISSIONS AT
NATURAL GAS
STATIONS

2. 52
In addition to the emission-free compression
of natural gas, other greenhouse gases such as
CO2andSF6canalsobecapturedandreturned
to the processes in an environmentally
friendly and sustainable manner. Sauer
already offers this latest technology, which
will be the industry standard in the future. •
If you would like to know more about the
solutions discussed in this article please
contact:
Bernd Schmidt
Global Business Development Recovery
HAUG Sauer Kompressoren AG,
St. Gallen (CH)
bernd.schmidt@haug.ch
MIDSTREAM & PIPELINES
Globally, there are various approaches to reduce emissions of greenhouse gases (GHG) such
as CO2 and CH4. The European Union targets a reduction of GHG emissions by 20% and an
increase of renewable energy by 20% until 2020 compared to the figures from 1990.
At the UN Climate Change Conference in Paris, an agreement was adopted on 12 December 2015.
The so-called Paris Agreement stipulates the limitation of anthropogenic global warming to well
below +2°C compared to pre-industrial levels.
Reducing Methane Emissions at
Natural Gas Stations
and improve energy efficiency, gas leaked
from stuffing boxes of reciprocating
compressors and/or the shaft seals of
centrifugal compressors can be collected. A
leakage gas recovery system can be installed to
compress these residual natural gas quantities
and inject them back into the suction line of
the compressor unit or into the discharge line
downstream of the compressor.
There is a huge potential for retrofitting
recovery systems, e.g. in the U.S. natural
gas industry there are approximately 50,000
reciprocating compressors installed. The
average compressor is a four throw machine
with four main stuffing boxes, resulting in a
total amount of 200,000 potentially leaking
stuffing boxes.
Sauer Compressors with the product lines
Sauer and HAUG provides solutions for the
gas industry to achieve the challenging climate
targets in the long term, both for new and for
existing plants. Technologies that have been
proven over the past decades in the field such
as magnetic coupling drives and hermetically
gas-tight compressors have led to leakage-free
gas compression and therefore zero emission.
Reducing methane leakages in the natural
gas sector can help achieving these goals.
It can also provide natural gas companies with
a financial benefit as methane is a valuable
resource when transported to a market or
utilized on-site.
Natural gas is gaining importance as a low-
emission fuel because of the growing demand
for energy, the increasing public environmental
awareness and its favourable properties. As
a result, the supply of natural gas has risen
steadily in recent years.
Booster stations along the pipelines,
underground cavern or aquifer storage facilities
and natural gas terminals up to CNG filling
stations are elements of an efficient supply. The
natural gas pressure of long-distance pipelines
is between 35 and 85 barg. Depending on the
demand, compressors at natural gas storage
facilities compress the natural gas from the
pipeline up to a final pressure of over 300 barg.
However, natural gas, along with carbon
dioxide, nitrous oxide and fluorocarbons (e.g.
SF6), is one of the main GHG that contribute
to global warming. Methane is 25 times more
harmful than CO2 and causes about 20% of the
anthropogenic greenhouse effect.
At the natural gas value chain, from the
wellhead to the end consumer, approximately
1% of the natural gas produced is released
into the atmosphere. Looking at the natural
gas imports from Russia to Germany of
approximately 100 Billion m3/a, 1% loss adds up
to the enormous amount of 1 Billion m3/a of gas
leakage per year. Reciprocating and centrifugal
compressors account for approximately 47% of
the total leakage.
Due to this problem, new European natural gas
compression projects are launched with “Zero
Emission” or “No Flare” requirements. Retrofits
are mandatory in order to fulfil latest legal
environmental regulations.
To reduce methane greenhouse gas emissions
Fig. 1 Percental leakage allocation during gas transmission and storage incl. reciprocating
and centrifugal compressors.