tion, but it does offer some relief as the
search for more sustainable options con-
tinues.
“Looking at, for instance, methanol,
wind or solar powered vessels, it is clear
that a lot of development still needs to be
done,” Kaljala says.
GOING CLEAN
DNV GL observes in its White Paper that if
produced from renewable energy or bio-
mass, the carbon footprints of methanol
and hydrogen can be significantly lower
than those of HFO and MGO. According
to DNV GL, the cleanest fuel is hydrogen
produced using renewable energy. Lique-
fied hydrogen could be used in future ship-
ping applications.
However, because of its very low
energy density liquefied hydrogen requires
large storage volumes, which may pre-
vent hydrogen from being used directly
in international deep-sea shipping. In a
sustainable energy world where the entire
energy demand is covered by renewable,
CO 2 ‑free sources, hydrogen and CO 2 will
be the basic ingredients for fuel produc-
tion, most likely in the form of methane
or diesel-like fuels produced in a Sabatier/
Fischer-Tropsch process.
TARGET: ZERO-CARBON FUELS
The White Paper argues that, looking
Olli Kaljala from Bureau Veritas says that ships without emissions are not likely to become
mainstream very soon.
ahead, LNG has already overcome the hur-
dles of international legislation, and meth-
anol and biofuels will follow suit very soon.
It will be a while before LPG and hydro-
LNG LEADS THE PACK times the greenhouse gas effect of CO 2 . gen are covered by appropriate new reg-
Potential alternative fuels for shipping are Nevertheless, engine manufacturers claim ulations within the IMO IGF Code as well.
numerous: LNG, LPG, methanol, biofuel that the tank-to-propeller (TTP) CO 2 -equiv- The existing and upcoming environmen-
and hydrogen are often listed as the fore- alent emissions of Otto-cycle dual-fuel (DF) tal restrictions can be met by all alternative
runners. Among the emerging new tech- and pure gas engines are lower than those fuels using existing technology.
nologies, one finds battery systems, fuel of oil-fuelled engines.
cells and wind-assisted propulsion which
may offer a boost in the future.
However, the IMO target of reduc-
Niklas Rönnberg from Lloyds Regis- ing GHG emissions by 50 % by 2050 will
ter says that in the short term, LNG is a likely require widespread uptake of zero-
LNG has become the “pet fuel” for decent tool towards greener shipping. ”In carbon fuels and further energy efficiency
maritime, even if it is a fossil fuel (with the coming years, we are likely to see more enhancements. Fuel cells can use all avail-
lowest CO 2 emissions). It is also problem- hybrid solutions where electricity is utilised able alternative fuels and achieve efficien-
atic that the release of unburned meth- in some way – especially with regards to cies comparable to, or better than, those
ane (so-called methane slip) could reduce smaller vessels,” Rönnberg says. of current propulsion systems. However,
the benefit over HFO and MGO in certain Olli Kaljala from Bureau Veritas
engine types. Methane (CH 4 ) has 25 to 30 agrees that LNG is not a long-term solu-
24
seatec 1/2019
fuel cell technology for ships is still in its
infancy.