This section relates to the relevant consideration for the early adaption of e-methanol as an alternative fuel.
The main feedstocks for producing e-methanol are low emission electricity, water, and CO2. For low emission electricity, mature technologies like solar, wind and hydro are in place but not at the scale required. Key challenges in the production of e-methanol therefore remain availability of power-to-X (P2X) technology and scaling of low emission electricity. Main cost drivers for e-methanol production are the costs for low emission electricity, along with the cost of the electrolyzers needed for hydrogen production. Furthermore, a renewable source of CO2 is essential for producing e-methanol, but qualified renewable CO2 point sources will most likely not be available in the scale needed which may also drive cost. Biogenic CO2 point-sources (CO2 released as a result of combustion or decomposition of biomass and its derivatives) may have limited availability, and Direct Air Capture (DAC) is even more expensive. The potential use of nuclear electricity for e-methanol production remains uncertain and an area for further exploration.
Methanol synthesis based on natural gas or coal gasification is a mature technology but using renewable electricity as the main feedstock is new and a cost driver. Commercially mature electrolyzers (such as alkaline and PEM) are currently too expensive and inefficient to make e-methanol a competitor to other alternative fuels and fossil fuels. Global electrolyzer production capacity is not ready for massive power-to-X roll-out in large scale and record pace construction of new large-scale methanol plants is required if e-methanol is to have a significant role in decarbonizing shipping. The size of e-methanol plants is likely to be limited by the scale of CO2 source supply, thereby diminishing economies of scale, and increasing the cost of e-methanol.
Fuel storage, logistics & bunkering
As a chemical, methanol is transported globally today (more than 10 million ton/year), and a mature infrastructure exists along with guidelines for bunkering. However, port infrastructure including terminals and bunkering facilities will have to be significantly expanded to meet the increased capacity requirements of potentially hundreds of millions of tons maritime fuel per year. Standards and safety requirements do not represent any new major challenges.
Onboard energy storage & fuel conversion
Methanol is liquid at ambient temperature and pressure, making it a favorable marine fuel in terms of storage and handling.
Dual-fuel two-stroke and four-stroke methanol engines are commercially available, and operational experience as marine engine has been obtained in the past decade onboard different ship types. Methanol engines are being developed and commercialized for wider size ranges and are not expected to be size restricted. PEM fuel cells may run on hydrogen from reforming of methanol, and this could be an initial option for auxiliary power. Solid Oxide Fuel Cells (SOFC) may run on methanol – perhaps with pre-reforming - but SOFCs are significantly less mature. Boilers using methanol as a fuel are in the final stage of development.
Onboard safety & operations
Through e.g. chemical tankers operating on methanol as a marine fuel, the safe handling of methanol as a low flash-point fuel on vessels is an established practice. No expected obstacles regarding onboard fuel safety and operations are present but require revised onboard practices, crew competence and safety management systems.
Dual-fuel engines fueled by methanol are in operation and no significant obstacles regarding engine emissions (NOx, SOX, and PM) remain. Onboard NOX emission reduction using known technologies is needed for regulatory compliance. Methanol combustion does release CO2 tank-to-wake - but for e-methanol produced with carbon sourced from a biogenic source, close to net zero emission can be obtained well–to–wake.
Green methanol combustion is hence considered a viable low emission marine solution.
Regulation & certification
Detailed methanol fuel quality specification under International Maritime Organization (IMO) is not fully implemented. This would be necessary for large scale deployment of e-methanol as a maritime fuel.
Life cycle assessment policy needs to be developed. Regulating the climate impact of fuel use from a life cycle perspective offers the industry the opportunity to establish sustainable fuel production and consumption patterns. By regulating the upstream (well-to-tank) climate impact, fuel users can select fuels with solid sustainability credentials. Regulation from a life cycle perspective also reduces the risk of burden shift of climate impact from the downstream (tank-to-wake) part of the value chain to the upstream. This is an important consideration for alternative marine fuels whereby much of the climate impact resides in well-to-tank activities.
Certification of CO2 point sources that are considered renewable is required. Well-to-wake greenhouse gas quantification for e-methanol not developed in key regulatory bodies such as the European Union (EU) or IMO. The use of methanol as a fuel has been approved by IMO with issuance of Interim Guidelines and rules will soon be integrated into the IGF code where low-flashpoint fuel rules are placed.
Methanol as a marine fuel: Prospects for the shipping industry - Documentation of assumptions for NavigaTE 1.0 (2021)