Scientists from Nanyang Technological University in Singapore and Technical University of Denmark presented one of the most major studies dedicated to methanol as an alternative to conventional marine fuel.
Global maritime traffic provides for 80% of the global trade, and it continues to be the source of almost 3% of global CO₂ emissions. The International Maritime Organization (IMO) demands to cut these emissions by 70% by 2040 and to completely eliminate them by the end of the century. However, the transition to new types of fuel is impeded by the fact that the existing fleet is designed to operate on heavy petroleum fractions, hence, any solution should be technically compatible, safe and economically feasible.
Methanol seems to be one of the most efficient solutions in this context. Different from hydrogen or ammonia, it maintains liquid state under normal conditions, which makes storage and bunkering easier. There are practically no sulfur emissions during combustion of methanol, and the volumes of nitrogen oxides and solid particles decrease manyfold. In addition, methanol may be received from many different sources – from natural gas and biomass to carbon dioxide captures from the atmosphere.
The researchers analyzed three value chains: methanol from natural gas; bio-methanol received from plant debris (palm leaves or cornstalk); and electro-methanol synthetized from hydrogen and CO₂ when using renewable energy sources. Low-sulfur marine bunker oil was used as reference.
The obtained results turned to be quite impressive. Methanol from natural gas demonstrated much cleaner combustion, however, the full life cycle analysis showed carbon footprint 9% higher vs low-sulfur marine bunker oil. Bio-methanol and electro-methanol, on the contrary, allowed for reducing the emissions by 50–80% depending on the type of feedstock and the method of receiving CO₂. The options, when carbon dioxide had biogenic origin or was captured from the atmosphere, showed the most convincing results. In these cases the carbon cycle was practically closed.
The researchers also identified that environmental advantages of methanol are not limited to climate. Decreasing the emissions of sulfur, soot and nitrogen oxides leads to noticeable improvement of the air quality in the areas of ports. The calculations show that transfer to methanol can decrease the loss of healthy years of life (DALY metric) down to 73%, which reflects the reduction of respiratory and cardio-vascular diseases.
From natural resources using standpoint methanol also looks more advantageous: its production requires much less non-resumable feedstock. According to the estimates by the researchers, the load on the resource base is reduced down to 90% vs the traditional fuel.
Nevertheless, the economics remain the main barrier. The full life cycle of methanol-fueled vessel is approximately 5% more expensive than operating the vessel on fossil fuel. The main reasons are high CAPEX for equipment and high volatility of fuel prices. However, when external effects are included into the calculation (damage to nature, climate and health), the situation changes drastically. Using the methodology of social Life Cycle Costing methodology (sLCC), the researchers converted environmental and social implications into cash equivalent. Eventually in 86% of probable scenarios methanol turned out to be preferable to traditional bunker fuel oil, if real social costs are taken into account.
The researchers emphasize that large scale deployment of methanol-based fuel will be very difficult without government support. Hence, they propose a set of measures including subsidies for building and revamp of vessels, long-term fuel supply contracts and introducing carbon tax in the range of 50-60 USD per 1 ton of CO₂. At such level of emission prices, methanol proves to achieve economic parity with traditional petroleum products.
Scalability of production also remains among the global challenges. Even when engaging all the available agricultural waste, bio-methanol output will coven no more than 10-12% of the global fleet needs. Electro-methanol should cover the remaining needs, and it will directly depend on developing cheap resumable energy and CO₂ capturing technologies. Production of 1 ton of such fuel requires circa 9 MW-h of electric energy, and this indicator makes investment into RES the decisive factor of future fuel infrastructure.
