Paris agreement of 2015 mandates the reduction of Green House Gas emissions mainly these of carbon dioxide.
Although, shipping was excluded, IMO in an effort to reverse the trajectory of global warming, has set a roadmap of decarbonization last April in London at MEPC 72. These decisions were driven by reports that future GHG emissions will increase between 50 and 250%, if the “business as usual” of our days is followed.
The targets set by IMO are a reduction of the CO2 emissions by 50% compared to 2008 level and a reduction by 70% of carbon intensity by the year 2050. These targets were received with varying degrees of enthusiasm. Although, they appear to be realistic, they fall short from more extreme calls for zero emissions by 2035. The IMO goal is more realistic, since the technology which will allow for replacement of fossil hydrocarbon fuels with carbon-free ones, is at its teething phase. Hydrogen and ammonia are promulgated as the future king and queen of the multi-fuel future economy. Yet, at the present they do not represent financially attractive or technologically mature solutions.
Ammonia has half the energy of diesel, being three times cheaper than gasoline. It has the highest hydrogen content and it is a natural refrigerant with zero global warming potential. Storage of liquid ammonia under atmospheric pressure at -33 degrees Celsius does not present the hurdles of hydrogen which liquefies at -253 degrees Celsius. A solution to solve the cryogenic “disadvantage” of hydrogen would be to consume it immediately following its production. Another solution can be the employment of more exotic novel chemical compounds like the so called “Metal Organic Frameworks”.
Liquefied natural gas (LNG) and methanol are heralded as the most promising alternatives to drive decarbonization of the shipping sector. Utilization of alternative fuels has already begun with shipping stakeholders introducing ships burning cleaner fuels. Methanol, although toxic, corrosive, with low flash point is easier to store, since it is not cryogenic, but more expensive. It can be produced from natural gas, ideally with renewable energy. It boasts the lowest emission factor among fossil fuels equal to 1.375. LNG is estimated to impose an approximate 20% premium on price if it is utilized as a fuel. At the present, the low price of HFO deprives shipping from any motivation to utilize alternative fuels such as biofuels, relatively inefficient synthetic fuels, hydrogen and ammonia in tandem with fuel cells, solar power and wind energy as potential alternatives.
Moving to LNG and methanol is attractive as each of them has a biofuel counterpart, biomethane and biomethanol. This means that ships and infrastructure built for LNG and methanol can be also used for biomethane and biomethanol with minor amendments. Biofuels though cleaner than fossil fuels, are in direct competition with the food chain. Sustainability of their biomass feedstock for their production, is questionable. Another disadvantage of biofuels is that they tend to degrade after long term storage. A critical element valid for all alternative fuels is to utilize cost-effective production technologies. One sustainable solution can be the use of renewable sources of energy to produce the alternative fuels like for example carbon-free renewable electricity.
The conclusion in the International Transport Forum report that a combination, a mixture of all currently known technologies could result into a completely decarbonized maritime shipping by 2035, appears to be very optimistic. Alternative fuels produced by renewable energy can deliver much of the required GHG reductions, provided that the stumbling blocks of their bunkering, availability, cost and storage may be removed. Wind assistance, solar and electric propulsion can bring additional reductions. A necessary prerequisite is the improvement in efficiency which for example in solar panels is below 20%. Rapidly falling costs of batteries technology for electric propulsion make that technology a viable candidate for decarbonization. Operational measures such as lower ship speeds, smoother ship-port co-ordination and use of larger, more efficient ships under economy of scale could bring more GHG emission reductions. Speed reduction has a dramatic impact on reducing fuel consumption and emissions because of the cubic propeller law. A one knot reduction from 14 to 13 knots will result to 20% reduction in fuel consumption. If the longer duration of the trip is accounted for the reduction in fuel consumption is about 14%. Higher reductions in speed will yield even more dramatic reductions in the fuel consumption. It is understood that such reductions, dictated by the charterer, cannot be applied in perishable cargo or expensive one like fashion or electronic goods.
The mantra of “charterer pays” is still valid. Consequently, financial motives may have to be provided to propel shipping into abandoning oil-based fuel and turn into the carbon-free fuels. Governments should encourage green shipping culture by supporting research into zero-carbon technology. Ports should provide cold ironing power facilities, electric charging systems and bunkering facilities for alternative fuels. A considerable amount of power is required to operate all functions on a vessel. This is not only lighting, but also heating, hot water, fans, engines etc. that need to be supplied. The ports of Los Angeles and Long Beach pave the way by installing thick forests of solar panels on neighboring rooftops. Shipping stakeholders should measure the carbon footprint of their fleets and employ transport options with zero-carbon ships. Private and public financial institutions should provide financial incentives and encouragement in that direction of investment.
The Initial Strategy of IMO aims to phase out GHG emissions from shipping “as soon as possible in this century”. Shipping’s first-ever absolute emissions targets have been set. IMO promotes the so called short term measures during the first phase of decarbonization. Low hanging fruits are the speed reduction and the reduction of the attained Energy Efficiency Design Index, EEDI. Predefined reduction of EEDI may be pushed back, by accelerating its implementation, even-though it is a known fact that tankers and bulkers will have hard time to comply with the requirements. Phases 2 and 3 of EEDI reduction of 20 and 30% respectively will be implemented in 2020 and 2025. Proposals for earlier implementation at IMO did not pass for this type of ships.
It is imperative to improve the energy efficiency of ships through technological and design measures so we can achieve the needed emission reductions. Available options are hull design improvements, hydro-dynamically optimized, built with lighter stronger materials. The easy and drastic way of reducing the power to achieve the required EEDI should be prevented. Towards that direction IACS in cooperation with IMO have unveiled the minimum power guideline to avoid under-powered ships in adverse weather conditions. It can be shown that EEDI KPI is proportional to speed squared. Consequently the promulgated 20 and 30% required EEDI reductions are equivalent to 11 and 16% service speed reduction. Although this is a low hanging fruit, the philosophy of EEDI is to apply design measures to achieve the index reduction.
Operational measures such as reduced speeds, efficient ship-port interfaces and bigger ships carrying more cargo and burning less fuel are necessary to realize decarbonization in combination with new fuels and renewable energy. Wind-assisted ships reap additional reductions. The first electric ships already pioneer transport on short-distance routes. It is a fact that only a combination of operational measures, technical innovation and alternative fuels will deliver sufficient GHG reductions.
Incentives for promoting alternative fuels warrant more attention. Discussions at the IMO currently focus on measures to make ship design and operation more energy efficient. Transition to alternative fuels must be accelerated and pursued in parallel with improvement in efficiency. There is also strong need to mitigate the adverse impacts of decarbonization on trade in developing economies and small island states. If it is intended to impose Market Based Measures in an effort to curb consumption, encourage fuel conservation, while collecting money which can be used for research on new fuels and propulsion options, the most straightforward one is imposition of a levy on the fuel.
LNG, although not being a carbon-free fuel, it is an excellent bridge fuel to transit towards carbon-free fuels. The main problem associated with LNG is the unburned methane escaping to the upper layers of the atmosphere. This is known as “methane slip” and it occurs predominantly in internal combustion engines of low gas pressure following the Otto cycle. Nevertheless, even with 1% slip, it can be shown that emission factor is about 3, still superior to the one for HFO and diesel. Methane is a potent GHG being about 25 times stronger than CO2. Methane also has higher calorific value than HFO.
Methane leakage and slip is more pronounced during the mining and distribution of natural gas. It is a fact that methane is produced in the guts of ruminant livestock as a result of methanogenic microorganisms. A sheep can produce about 30 liters of methane each day and a dairy cow up to about 200.
Fuel choice is key factor in decarbonization. Shipping is at a pivotal point regarding future fuel choices. Impact of emissions from a fuel needs to be considered on a life cycle basis. Upstream emissions released with growing and/or manufacturing, distribution, use and disposal of a shipping alternative fuel must be accounted for. In that context carbon-neutral fuels of the fuel will cause zero increase in the CO2 to the atmosphere. For example methane or diesel obtained from captured carbon with renewable energy. Even further, if produced CO2 is captured, the tally becomes negative and we thus deal with carbon-negative fuels. It seems that we are going to welcome the CO2 scrubbers of the future.
It seems that the real fuel kings and queens of the future will be the renewable sources of energy. They provide limitless sustainable energy having gained societal acceptance in contrast to another clean form of energy, nuclear power. It is most critical though to establish a culture of energy conservation and efficiency. This culture will make decarbonization a feasible task instead of a Shakespearean summer night dream.
* Technical Director Bureau Veritas Hellenic, Black Sea & Adriatic Zone