The Problems with Liquefied Natural Gas

With more than 90% of global trade moving by ocean transport, maritime shipping is a major driver of the world economy. However, shipping has a serious pollution problem that threatens our climate, communities and the marine environment. If we are to avert climate catastrophe, the shipping sector must immediately begin to eliminate the 1 billion-plus metric tons of greenhouse gases it emits every year.

In response, the International Maritime Organization (IMO)—the United Nations body that governs global shipping—passed a new strategy to eliminate the sector’s greenhouse gas emissions in July 2023. The 2023 strategy is more ambitious than the earlier one it replaces and covers full life cycle (also known as well-to-wake or WtW) emissions of all greenhouse gases (GHG), not just those from burning fuel onboard and not just carbon dioxide (CO₂). The ultimate goal is to reach net-zero emissions by 2050 through emission reductions of 30% by 2030 and 80% by 2040. To reach these targets, a massive energy transition from dirty conventional marine fuels to zero-emission energy (like wind-assisted propulsion) and fuels is imperative. There is no time to waste on false climate solutions like Liquified Natural Gas (LNG)—a fossil fuel with serious global warming and public health implications.

Unfortunately, international shipping has been increasing its investments in LNG. What is behind the industry’s embrace of LNG, and what are the potential implications on efforts to reduce shipping’s GHG emissions?  A new report from Ocean Conservancy and Energy and Environment Research Associates, “Analysis of Liquified Natural Gas as a Marine Fuel in the United States,” takes a comprehensive look at the full life cycle (i.e., extraction, production, transport, storage and use) of LNG to answer these questions.

What is LNG?

Liquified natural gas is not exactly “natural”. To produce LNG, natural gas, more than 80% of which comes from hydraulic fracturing (“fracking”) in the United States, is liquified by cooling it to -162^o Celsius (-260^oFarenheit). After this liquefaction process, LNG is transported via truck, rail or ship to receiving terminals, where it is regasified and stored before distribution to end-users. 

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The LNG Value Chain

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LNG is a risky but growing maritime fuel choice

Given the intensifying focus on mitigating global shipping’s climate impact, the drift toward LNG may be baffling to many. Several regulatory and market drivers can help explain this conundrum. LNG has negligible sulfur content that supports low sulfur oxide (SO_x) emissions. When the IMO’s regulation to cut SO_x emissions went into effect in 2020, LNG became a growing alternative fuel choice for marine transportation. When combusted, LNG also has lower CO₂ emissions and so was seen as a “transition” fuel for the sector when the initial IMO greenhouse gas strategy focused only on CO₂emissions from burning fuels on vessels. These factors, along with LNG’s increasing availability and lower price compared to emerging zero-emission fuels, are behind much, if not all, of the shift to LNG. 

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Growth in the LNG Fleet

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However, LNG is not a low greenhouse gas fuel and has serious climate implications. It is composed almost entirely of methane, which is 27-30 times more potent than CO₂ as a greenhouse gas over a 100-year timeframe and is 82.5 times more potent than CO₂ over the near term. Methane emissions from international shipping increased by approximately 150% between 2012-2018, primarily attributed to the increase in use of LNG as a propulsion fuel with LNG accounting for around 3.8 – 4.6% of energy consumed by international shipping per GHG4. 

These are just the “tank-to-wake” onboard methane emissions of LNG. Methane leaks or slips and intentional venting of uncombusted methane for routine maintenance or maintaining storage pressures actually occur all along the LNG value chain. 

The life cycle methane emissions of LNG matter. Our report presents evidence that in addition to their global warming implications, these emissions from increased LNG consumption also have impacts on human health and environmental justice. 

Methane emissions, which can result from the production and consumption of LNG, are linked to significant impacts on air quality by influencing concentrations of ground-level ozone. Ozone exposure causes and exacerbates respiratory issues, including asthma, and has been linked to cardiovascular disease and premature death. Additionally, harmful pollutants are released during natural gas extraction, processing and liquefaction, potentially impacting the air and water quality of nearby communities.

The combustion of LNG generally has globally distributed risks, whereas the upstream (well-to-tank) emissions from processes to produce LNG can have a more localized effect. Communities near LNG production facilities may face health consequences resulting from exposure to pollutants, economic impacts due to fluctuations in property values, and socio-economic and cultural changes arising from their proximity to emerging natural gas projects. Our report documents links between LNG production and instances of environmental injustices tied to ethnicity, culture, gender and income.

For the maritime sector, policy decisions and implementation timelines can shape choices in engine, fuel and exhaust after-treatment and guide infrastructure development. We can see this in the growth in uptake of LNG in order to comply with earlier regulations. The IMO’s 2023 strategy marks a turning point toward mitigating all greenhouse gas emissions along the entire maritime fuel and energy value chain. The process is now underway to design and adopt the technical and economic policies to drive the maritime energy transition. Given the questions over the costs and feasibility of retrofitting LNG-fueled vessels and supporting infrastructure that is presented in the report, this growing inclusion of methane in regulatory frameworks will play a pivotal role in deterring LNG use.

It’s abundantly clear that LNG use as a marine fuel does not meet stated climate goals and can perpetuate environmental injustices. Political intervention, not only to better regulate methane but also to improve the economic viability of near-zero and zero-greenhouse gas fuels, is imperative to meet 2030, 2040 and 2050 climate timelines. This could take form in penalties to polluters through emissions pricing, or subsidies to support production of energy alternatives—or a combination of both. To reach zero-emission shipping, we need to bypass false fossil solutions like LNG and focus on maximizing efficiency to reduce fuel use and invest resources in true zero-emission solutions.

In its efforts to identify and advance ocean-based climate solutions, Ocean Conservancy is leading a global, multiyear campaign to completely eliminate the gigaton of GHG pollution that the maritime shipping sector emits each year. As a rapid transition to zero-emission marine fuels is essential, Ocean Conservancy partnered with Energy and Environment Research Associates to analyze the arguments that LNG is the best option for a “bridge” fuel. The report is the latest contribution to Ocean Conservancy’s growing body of research that is informing and advancing the maritime energy transition. 

The LNG landscape—from fuel production and bunkering to vessel operations and environmental considerations—is rapidly evolving. This report covers all aspects of LNG as a marine fuel, including discussion of policies and regulations; LNG engine technologies and emissions; the global and U.S. LNG vessel fleets; production, import and export of LNG; and the health and equity implications of LNG. The main chapters are supported by additional detail in the Supplemental Information sections found at the end of the report.

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