Policy Memo: Reduction of GHG Emissions from International Shipping from Manure-based Biomethane

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To: Marine Environment Protection Committee (MEPC) 

 

From: Ryan Harb

 

 

INTRODUCTION

 

MEPC 83 approved draft amendments to MARPOL Annex VI on the IMO Net-Zero Framework for adoption at MEPC/ES.2. Draft regulation 31 of MARPOL Annex VI sets out that “The goal of this chapter is to reduce greenhouse gas (GHG) emissions from international shipping as soon as possible.” 

Draft regulation 31 of MARPOL Annex VI further provides areas for effectively promoting the energy transition of shipping and providing the world fleet with a needed incentive, which should positively help enable shipowners to negotiate long term contracts for zero or near-zero emission fuels (ZNZs) with energy suppliers. 

MEPC 83 also noted the indicative list of guidelines, governing provisions and other guidance accompanying the draft amendments on the IMO Net-Zero Framework, to be developed or to be amended (MEPC 83/WP.11, annex 2) which includes the technical tool to collect and convey information relevant for the life cycle GHG intensity assessment (LCA) of a fuel. 

To expedite the rapid development of these guidelines on LCA of a fuel for adoption as soon as possible, which is a matter of great urgency if the IMO Net-Zero Framework is to be successfully implemented, we urge adoption of an initial version for LCA of a fuel no later than MEPC 84 in May 2026. Moreover, to send a clear and immediate signal to industry, it is essential that these guidelines include recognizing negative GHG emissions from manure-based biomethane production for their methane abatement potential. 

The detailed rationale for suggesting a negative GHG emissions rate for manure-based fuels and the simple method for calculating it is set out in this document, which also suggests that to ensure that the IMO Net-Zero Framework will have sufficient ZNZs starting in 2028, the Committee should strongly consider aligning LCA guidelines with the EU Renewable Energy Directive (RED III), which already accounts for negative methane emissions from livestock manure feedstocks.

As also set out in more detail in this document, we suggest that the Committee can have confidence, with a high degree of certainty, that if the negative emissions rate for manure-based fuels was adopted and aligned with EU RED III, that the IMO Net-Zero Framework would be much more likely to succeed in reducing the GHG emissions from international shipping as soon as possible. Energy producers and shipowners would have the clarity and confidence necessary to make the investment decisions required to immediately accelerate the uptake of new ZNZs produced for the marine sector.

 

THE URGENT NEED FOR GUIDELINES ON METHANE ABATEMENT TO BE ADOPTED AT MEPC 84

 

Biogas, which is derived from the biological decomposition of manure, agricultural waste, municipal solid waste (MSW), and other organic waste streams, is one of the main renewable gases available today to help decarbonize the shipping industry. With additional conditioning and removal of contaminants, biogas can be upgraded to biomethane and other advanced fuels to be utilized in the shipping industry’s vast existing energy infrastructure and global fueling network. 

When manure is anaerobically digested to capture biogas and produce biomethane, it prevents methane release that would otherwise occur in conventional manure storage systems. The EU RED III (Directive 2023/2413) recognizes this climate benefit by allowing negative emissions accounting for manure feedstocks under its GHG methodology (Annex VI). The Joint Research Centre (JRC) of the European Commission has proposed default values and methodologies for quantifying these avoided emissions, reinforcing the scientific basis for their inclusion in policy frameworks. 

From 2018 and 2023, methane emissions rose faster than at any time in recorded history, imperiling efforts to limit global warming by mid-century.[1] As a greenhouse gas, methane is 80 times more potent than CO2 in the first 20 years after it is released into the atmosphere.[2] Globally, manure management contributes approximately 237 million metric tons of CO₂ equivalent (MMTCO₂e) in methane emissions annually. This represents about 4% of total anthropogenic methane emissions.[3] Within the agricultural sector, manure and enteric fermentation together account for 32% of global methane emissions, with manure alone contributing a substantial portion of that.[4] 

 

HIGHER PRODUCTION COSTS AND SMALLER VOLUMES WITH CARBON NEGATIVE FUELS

 

Despite their environmental benefits, manure-based biomethane systems face uphill economic challenges. According to the Biomethane Industrial Partnership (BIP), the total cost of biomethane production, including biogas generation and upgrading, ranges from €54 to €91 per MWh, equivalent to approximately $18 to $31 per MMBtu.[5] Systems using manure and other public feedstocks often incur higher capital and operational costs due to the need for extensive pre-treatment and digestate handling infrastructure. 

Compared to other feedstocks like maize silage or food waste, manure often yields lower methane per unit of input and requires more complex logistics, making it less economically competitive.[6] However, manure-based systems deliver outsized environmental benefits through methane capture and nutrient recycling, and must be appropriately rewarded within policy frameworks to reflect their climate value.

Additionally, manure-only biomethane projects also face challenges related to economies of scale, as they are typically limited in size and unable to achieve the cost efficiencies seen in larger, centralized systems. Most manure-only biomethane plants produce <150,000 MMBtu’s per annum (equivalent to ~2,900 MT of bio-LNG) depending on livestock count and system efficiency.[7] Manure facilities are more frequently deployed across the world, but larger MSW facilities constitute the bulk of biomethane production capacity, and can often exceed 500,000 MMBtu’s per plant per annum. 

These limitations in size and cost underscore the need for targeted policy support that includes credit recognition for methane abatement to make manure biomethane facilities both financially viable and scalable across the world.

 

Calculation of blending manure-based biomethane with LNG for Bio-LNG into ships 

 

For ZNZs used by a ship under the proposed IMO Net Zero Framework, pursuant to Resolution 3.13 of MEPC.376(80) Guidelines on Life Cycle GHG Intensity of Marine Fuels (LCA Guidelines)[8], “A fuel batch may be a mix of fuels made from various feedstocks and sources (e.g. by blending 20% biodiesel into fossil MGO). Blended fuels should be included in the certification schemes and relevant GHG default or actual emission factors (gCO2/MJ) determined in proportion to the energy of each fuel part of the blend.”

For calculating Well-to-Tank (WtT) emissions of bio-LNG for example, -100gCO2eq/MJ is a realistically achievable value for biomethane produced from manure according to EU RED III. “If CO2 capture also takes place during biomethane production in order to replace fossil CO2 (CCR) or store it geologically (CCS), WtT values lower than -120 gCO2eq/MJ can also be achieved. There are several projects in Europe that are already producing and marketing these qualities.”[9] 

Tank-to-Wake (TtW) combustion emissions quantify the CO₂ released when bio-LNG is burned on board. These emissions are calculated by multiplying the ship's total energy use by the fuel's CO₂-per-energy emission intensity, which is itself derived from the fuel's carbon content and calorific value. 

For a dual-fuel LNG ship using a bio-LNG component, the blended GHG emissions rate should be calculated on a Well-to-Wake (WtW) life cycle basis as follows:

For bio-LNG Blend: As an example, a dual-fuel LNG cargo ship will incorporate between 5-100% bio-LNG, calculated on a life cycle basis, to meet the GFI threshold of 19.0 gCO2eq/MJ for achieving ZNZ status during the initial period until 31 December 2034, pursuant to regulation 39.1 of MARPOL Annex VI, and taking account of the LCA Guidelines.

Assuming a large dual-fuel LNG cargo ship uses 20,000 MT of LNG per annum, where the biofuel component is bio-LNG, the bio-LNG component would equal 20,000 MT x 5% to 100% = 1,000 to 20,000 MT. The fossil LNG component would equal the remaining volume. 

To put this into commercial terms for a bio-LNG energy supplier and shipowner, 20,000 MT of bio-LNG is equivalent to ~1,050,000 MMBtu’s, which is the production volume from five to seven average size biomethane plants with manure-only feedstock. Additionally, bio-LNG produced from alternative feedstocks (agricultural waste, MSW, food waste) would have a higher WtW emissions value compared to manure only, but the ample availability of these feedstocks is critical for achieving economies of scale and keeping fuel prices low for shipowners. 

data

Table 1 - Typical and default values for biomethane (Directive (EU) 2018/2001 of the European Parliament and of   the Council)[11]

 

CONCLUSION 

 

Investment thrives on market certainty. Assuming the NZF is approved at MEPC 85/ES.2, incentivizing the accelerated investment in ZNZs will be essential to ensure the success of the IMO Net-Zero Framework. Unless energy producers and shipowners have near-term certainty and clarity for allowing negative GHG emissions from manure-based biomethane production, ethical investment decisions will be delayed with respect to sourcing ZNZs, and the construction of ships that use ZNZs. 

There is already a multi-year lead time between making investment decisions and ZNZs becoming readily availability. Delaying important regulatory decisions will prevent shipowners from entering into contracts and off-take agreements with energy producers and jeopardizes achievement of IMO’s GHG reduction goals. It is therefore essential that the Committee takes a bold and pragmatic approach to finalize and adopt an updated version for LCA of a fuel no later than MEPC 84, and makes significant progress on finalizing these guidelines at ISWG-GHG 21.

 

ACTION REQUESTED OF THE COMMITTEE 

 

The Committee is invited to consider the proposed recommendations as described in document, with a view to their finalization and adoption at MEPC 84 at the latest. 

To expedite development of the guidelines at ISWG-GHG 21, the Committee is invited to agree that:

  • In view of the urgent need for energy producers and shipowners to have confidence and certainty to make critical investment decisions, adoption of an initial version for LCA of a fuel should be approved at MEPC 84;
  • The initial version for LCA of a fuel should treat all fuels equally depending on their WtW emissions. Fuels with negative WtW emissions should be eligible, otherwise, they are severely penalized; 
  • To send a clear and immediate signal to energy producers and shipowners, recognizing methane abatement in lifecycle scoring should also be announced at MEPC84;
  • A timely opportunity exists to align with EU RED III standards, particularly Annex VI and the Joint Research Centre’s recommendations, to ensure consistency and scientific credibility to GHG emissions for fuels;

These steps would not only advance maritime decarbonization but also tell a compelling public story about connecting climate-smart agriculture with an innovative transition to clean international shipping.

 

References:

 

  1. Global Methane Pledge Ministerial Factsheet 2024. Global Methane Pledge, 2024, https://www.globalmethanepledge.org/news/factsheet-2024-global-methane-pledge-ministerial
  2. Raymond, Peter, and Steven Hamburg. Yale Experts Explain Methane Emissions. Yale Sustainability, 18 Nov. 2024, https://sustainability.yale.edu/explainers/yale-experts-explain-methane-emissions 
  3. Agricultural Sources and Mitigation Options. Global Methane Initiative, https://www.globalmethane.org/documents/ag_fs_eng.pdf 
  4. Food and Agriculture Pathway. Global Methane Pledge, 2022, https://www.globalmethanepledge.org/annual-report/food-and-agriculture-pathway 
  5. Task Force 4: Biomethane Market Design and Incentives – Full Study Slidedeck. Biomethane Industrial Partnership, Oct. 2023, https://bip-europe.eu/wp-content/uploads/2023/10/BIP_TF4-study_Full-slidedeck_Oct2023.pdf 
  6. Assessing the Sustainable Potential and Cost of Feedstocks for Biogas and Biomethane. International Energy Agency, 2025, https://www.iea.org/reports/outlook-for-biogas-and-biomethane/assessing-the-sustainable-potential-and-cost-of-feedstocks-for-biogas-and-biomethane
  7. Chapter 8: Financial Analysis of Biomethane Production. Biomethane from Dairy Waste: A Sourcebook for the Production and Use of Renewable Natural Gas in California, Sustainable Conservation, https://www.suscon.org/pdfs/cowpower/biomethaneSourcebook/Chapter_8.pdf 
  8. European Sustainable Shipping Forum. ESSF SAPS WS2 Report on Fuel Certification Procedures to Support Implementation of FuelEU Maritime. European Commission, 24 Apr. 2025, https://transport.ec.europa.eu/document/download/1dd51746-c10e-4d87-a607-0494713cd416_en?filename=ESSF_SAPS_WS2_Report_on_Fuel_Certification-March_2025.pdf
  9. agriportance GmbH. “FuelEU Maritime.” Agriportance, www.agriportance.com/en/blog/fuel-eu-maritime. Accessed 21 Sept. 2025.
  10. European Sustainable Shipping Forum. ESSF SAPS WS2 Report on Fuel Certification. European Commission, 22 Mar. 2025, https://transport.ec.europa.eu/document/download/1dd51746-c10e-4d87-a607-0494713cd416_en?filename=ESSF_SAPS_WS2_Report_on_Fuel_Certification-March_2025.pdf
  11. European Union. Directive (EU) 2018/2001 of the European Parliament and of the Council on the Promotion of the Use of Energy from Renewable Sources (Consolidated Version). EUR-Lex, 20 Nov. 2023, https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02018L2001-20231120. Accessed 22 Sept. 2025.