Greening gas delivery: LNG versus pipelines
Natural gas pipelines generally have lower carbon footprint than LNG operations
BY SALEEM H. ALI FOR GREENING OF OIL
While much has been written on the carbon footprint of oil versus natural gas, scant attention has been paid to the transport and delivery of either fuel. In comparison to oil, which is largely transported worldwide by a fleet of more than 38,000 marine tankers, 93 percent of the world’s natural gas continues to be supplied through pipelines. More than 60 countries have, on average, 2,000 kilometers, or 1,243 miles, of pipeline for gas transmission within their borders and about 10,000 kilometers, or 6,214 miles, of new pipelines are planned for this decade, often traversing difficult terrain and deep marine waters.
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However, the role of pipelines is diminishing as liquefied natural gas, or LNG, operations provide the fuel to a greater number of markets. LNG is natural gas that is cooled to -161 C, at which point it becomes a liquid and occupies only 1/600th of its original volume, making it convenient for shipping.
The process to bring the gas to such low temperatures requires highly capital intensive infrastructure. Liquefaction plants, specially designed ships fitted with cryogenic cooling tanks, regasification terminals and domestic transmission infrastructure all make LNG relatively expensive in construction and operational cost.
LNG’s advantage is it offers access to distant markets
The clear advantage of LNG shipments lies in access to distant markets which become uneconomical for pipeline transport, usually beyond 3,000 kilometers, or 1,864 miles.
LNG shipments also avoid lengthy negotiations on international pipeline routing and security enforcement, though the rise of piracy on the high seas in recent years has changed this dynamic considerably.
The environmental costs of pipelines for oil have often been far more publicly debated than for LNG.
Pipeline projects such as the Baku-Tblisi Ceyhan (Azerbaijan, Georgia and Turkey), Chad-Cameroon; Camisea (Peru); and the Yadana project (Burma/Myanmar) have become focal points for environmental activism. Campaigns targeting shareholders of parent companies of these projects as well as litigation have focused on the environmental disruption caused by the infrastructure that is needed to construct the pipelines.
Often the environmental concerns pertaining to these projects have been inextricably linked to indigenous conflicts over resource access and mitigation of impacts to livelihoods that may be affected by the pipelines.
However, if the pipeline infrastructure can be moved underground and the surrounding land restored after construction, the impacts can be greatly reduced.
Pipeline length a factor
Whereas oil pipelines can cause ecological damage due to leaks and spills, the only “spill” hazard from gas pipelines involves potential combustion of leaks that can lead to uncontrolled forest fires.
Monitoring of the pipeline route is therefore vitally important, using remote sensing technology and physical monitoring and security in key locations. With such measures in place, pipelines can also be a source of lasting cooperation between countries that can be considered a derivative planning benefit for international donors and multinational investment.
Energy usage and greenhouse gas emissions are perhaps the most significant areas where pipeline gas can have an advantage over LNG. However, this advantage is also highly dependent on various design factors. According to a recent study commissioned by the European Union, the typical energy “penalty” for gas delivery via pipelines is 10-15 percent (efficiency of 85-90 percent), whereas for LNG it is approximately 25 percent (efficiency of about 75 percent).
The efficiency for pipelines begins to decrease as the length of the project increases. This is also true for greenhouse gas, or GHG, emissions.
The energy used for the cooling process and subsequent decompression can be harnessed to some degree for various purposes. For example in Japan LNG users have found that the use of cryogenic power production for deep freeze food storage units can be a derivative benefit of LNG.
When comparing GHG emissions pipelines come out far ‘greener’ than LNG. For example, in Europe, pipeline transmission has a seven-fold lower carbon footprint than LNG. However, the GHG contributions of pipelines increase considerably over distance due to fugitive emissions of methane that are often inevitable along large pipeline tracks and these grow much faster than the transportation emissions from the tankers traveling over large distances.
Therefore, pipeline GHG emissions equalize emissions from LNG transport when transport distance is around 7,500 kilometers, or 4,660 miles.
Consumer appliances play a part
The quality of gas from LNG may be superior to piped gas in terms of energy provided on combustion since impurities are often removed during the processing of LNG. However, the pollution impacts of the two kinds of gas often depend on how effectively appliances are designed to use each kind of gas.
For example, a study conducted by Advantica Ltd. in England revealed that appliances that are designed for pipeline gas can produce higher nitrous oxide emissions when regasified LNG is fed to them.
Although gas producers such as Qatar have chosen to focus on LNG as their primary export route, pipelines continue to be a vital force in the gas transport sector. Inflationary pressures in recent years have also affected LNG building costs far more than pipeline construction costs. In one such analysis conducted by Jensen Associates in 2008, LNG costs from 2004-2008, rose twice as fast as pipeline construction costs.
Environmental costs may tilt the balance further in favor of pipelines at shorter distances but both sectors are likely to strive towards continuous improvement.
About the author
Saleem H. Ali is associate professor of environmental planning at the University of Vermont and the author of Treasures of the earth: need, greed and Sustainable future (Yale University Press, 2009). Ideas for this article were developed during a visiting fellowship at the Brookings Doha Center in 2009. It is Ali’s position that customers of natural gas should continue to monitor the technological improvements of both LNG and pipeline transport methods as the race towards greening the supply line continues. Visit Ali's University of Vermont page.
Links of interest
Theodoropolos, Theodore E. Oil, Gas and Petrochemicals, Doha: State of Qatar Publications, 2009. Data on pipeline per country from Oil and Gas Journal, February 2005.
Ali, Saleem and Parag Khanna, “Energizing Peace” Foreign Policy, November, 2009.
Kavalov, B, H. Petric and A. Georgakaki, Liqueified Natural Gas for Europe: some Important issues for consideration. Brussels, Belgium: European Commission, Joint Research Centre, 2009.
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