What Is Bioenergy? Shipping’s Bridge to Net Zero
Walk the fuel berths of Rotterdam or Singapore today and you’ll hear a quieter conversation happening alongside the hydrogen and ammonia headlines: bioenergy. It’s not the flashiest contender in shipping’s decarbonization race, but it’s arguably the most immediately usable one. Bioenergy refers to energy derived from organic matter — biomass — that can be converted into heat, electricity, or liquid and gaseous fuels. For an industry under pressure to cut emissions now rather than in a decade, that immediacy matters.
Breaking Down How Bioenergy Works
At its core, bioenergy taps the carbon stored in living or recently living material — crop residues, used cooking oil, animal fats, forestry waste, algae, even municipal organic waste. That biomass is converted through combustion, fermentation, gasification, or transesterification into usable energy carriers. In the marine context, the most relevant outputs are biodiesel (FAME), hydrotreated vegetable oil (HVO), and biomethane, often referred to collectively as biofuels or drop-in fuels.
The appeal lies in chemistry as much as policy. Because the carbon in biomass was recently absorbed from the atmosphere by the plants or organisms it came from, burning it is considered closer to carbon-neutral than burning fossil fuel extracted from the ground, where that carbon had been locked away for millions of years. This is the lifecycle logic regulators lean on when counting bioenergy toward emissions targets under frameworks like IMO’s carbon intensity rules and the EU’s FuelEU Maritime regulation.
Crucially, many bio-based marine fuels are chemically similar enough to conventional marine gas oil or heavy fuel oil that they can be blended into existing fuel systems with little or no modification to engines, tanks, or bunkering infrastructure. That compatibility is what separates bioenergy from alternatives like methanol or ammonia, which typically demand new engine designs, retrofits, and entirely rebuilt supply chains.
Where Bioenergy Is Already Working on the Water
This is where bioenergy stops being theoretical. Shipowners from Maersk to CMA CGM have run commercial vessels on biofuel blends — typically HVO or FAME mixed with conventional fuel at ratios from 20 to 100 percent — without touching the engine room. Wärtsilä, among other major engine manufacturers, has conducted extensive testing confirming that its two-stroke and four-stroke engines can run on various bio-blends with only minor adjustments to fuel handling and storage, given biofuels’ different viscosity and oxidation characteristics.
Ports in Northern Europe, particularly Rotterdam and Antwerp, have become de facto bioenergy bunkering hubs, supplying biofuel blends to container ships, cruise vessels, and offshore support vessels seeking a quick route to compliance with tightening carbon intensity indicators. Cruise operators have been especially active, since reputational pressure around emissions runs high in that segment and biofuels offer a low-disruption way to show progress without waiting for next-generation propulsion to mature.
Beyond propulsion, bioenergy also shows up onshore in port operations — biomass-fired combined heat and power plants supplying shore power, and biogas facilities processing waste from fish farms and food processing operations common in coastal economies. The maritime sector’s relationship with bioenergy, in other words, extends well past the fuel tank.
The Catch: Scale, Feedstock, and Scrutiny
None of this comes without friction. The single biggest constraint on bioenergy’s growth in shipping is feedstock availability. Used cooking oil and animal fat supplies are finite and already contested by road transport and aviation, both of which are racing toward the same limited pool of sustainable feedstocks. Scaling bioenergy to meaningfully supply global shipping, which burns roughly 300 million tonnes of fuel annually, would require feedstock volumes that current agricultural and waste-collection systems simply cannot deliver without raising difficult questions about land use and food competition.
There’s also growing scrutiny over lifecycle accounting. Not all biofuels are created equal — palm-oil-derived biodiesel, for instance, carries a far more troubling land-use and deforestation footprint than genuinely waste-derived HVO, and regulators are moving to tighten certification standards to prevent greenwashing. The EU’s Renewable Energy Directive and ISCC certification schemes are increasingly central to determining which biofuels actually count toward compliance targets.
Bioenergy won’t single-handedly decarbonize shipping, and few in the industry claim otherwise. But as a transitional fuel that works with today’s fleet rather than against it, it buys the sector precious time while methanol, ammonia, and hydrogen infrastructure catches up. The real test ahead is whether feedstock supply chains and certification standards can mature fast enough to keep that bridge standing.
