Using a high-efficiency variable-speed pump or slightly increasing the ship tank’s maximum pressure can enable zero-boil-off large-scale liquid hydrogen transfer, drastically reducing energy loss and improving the economic viability of LH₂ export terminals.
Moving liquid hydrogen is like carrying an ice cream cone on a blazing summer day—no matter how careful you are, the heat around you keeps melting it. Except in this case, the “boiling” happens at –253°C, and every tiny bubble that forms—called boil-off gas (BOG)—represents lost hydrogen, lost energy, and lost money.
In today’s article, we break down a fresh study that tackles one of the toughest problems in hydrogen shipping:
How do you transfer 160,000 m³ of liquid hydrogen from an onshore tank to a ship without losing any hydrogen at all?
This research looks at two strategies and shows how we can actually achieve near-zero—or even completely zero—boil-off during the transfer process. Let’s dive into the science, the engineering, and why this matters for the hydrogen economy.
Global hydrogen demand is skyrocketing. By 2050, up to 200 million tons per year of clean hydrogen may need to be moved around the world, with roughly 20 million tons shipped by sea.
But to make LH₂ shipping economically viable, ports need better infrastructure—especially systems that keep hydrogen cold and stable during transfer.
Why?
Because BOG is expensive:
The goal is simple: transfer liquid hydrogen with zero boil-off.
The reality? Much harder.
But this study shows it's possible—and explains how.
Boil-off gas forms when any source of heat—from pipes, pumps, tank walls, or pressure changes—warms the cryogenic fluid even slightly. Key contributors:
The big engineering question is:
Can we control the process well enough to avoid creating BOG altogether?
This research says yes—if you use the right pump strategy, or if you adjust the tank pressure correctly.
The study compares two pump configurations:
This pump can change its speed dynamically depending on the required flow.
It works with something called split-range control, where:
This avoids unnecessary “over-pressurizing” the fluid, which then must be throttled and depressurized—causing heat and boil-off.
Key finding:
When using a VSD pump, boil-off can be reduced to:
0% – 0.24% in the uncertainty analysis
This corresponds to 0–31 tons lost out of 11,281 tons transferred.
Pump efficiency matters A LOT
With a pump operating near 70% efficiency, zero-loss transfer is achievable.
With low efficiency (50–60%), losses increase.
What if you don't want to buy an expensive VSD pump?
You can simply allow the ship's tank to reach a slightly higher maximum pressure.
Base case is 1.15 bar(a).
The researchers found:
Key finding:
Increasing allowable pressure = less relative boil-off.
Because a higher ullage pressure reduces vaporization caused by incoming liquid.
But there’s a catch
More pressure in the ship tank means:
So this solution shifts complexity from the terminal to the vessel.
Each “loading train” in the model involves:
The system transfers 13,000 m³/h, filling four ship tanks to a total of 160,000 m³.
This is massive—it’s the size of future commercial LH₂ carriers currently being designed.
In the sensitivity analysis, several uncertain factors were tested:
The result?
Pump efficiency is by far the most important factor.
It impacts:
With low pump efficiency, even a VSD-controlled system struggles to avoid losses.
This means future LH₂ pump design efforts should prioritize:
Because these pumps don’t exist yet at this scale—engineers must invent them.
Even with vacuum insulation, the LH₂ pipe gains between 5.5–12 W/m.
Across 1100 meters × 2 lines, this becomes a major external heat load.
Heat → boils hydrogen → creates BOG.
But heat ingress is less important than pump inefficiency—though still significant.
Past studies suggested:
Slow filling → less boil-off
But this study finds something different:
Slow filling increases boil-off
Because the pump keeps generating high pressure → more throttling → more heat → more BOG.
This nuance shows previous research oversimplified the issue.
The TS (Temperature–Entropy) diagrams tell the story:
This “exergy destruction” is essentially wasted useful energy that turns into heat — exactly what you don't want when handling cryogenic fluids.
With VSD control:
This is why the VSD system achieves near-zero boil-off.
For the full 160,000 m³ transfer:
With VSD (good pump):
With fixed-speed pump:
That’s a huge difference:
This alone justifies investing in VSD and high-efficiency pump designs.
This study makes one thing clear:
Zero-loss LH₂ transfer is no longer a dream—it’s a real engineering pathway.
But to deploy this at ports worldwide, we need:
Liquid hydrogen is one of the cleanest, most energy-dense carriers for long-distance transport—but only if we handle it efficiently. This study shows that with:
…we can already achieve zero boil-off hydrogen transfer at export terminals.
That’s a massive leap for the hydrogen economy and a promising sign that LH₂ shipping could scale globally by 2030–2050.
If you're an engineer working on hydrogen systems, this research highlights a huge opportunity:
improving pump efficiency could unlock billions in value across the hydrogen supply chain.
Liquid Hydrogen (LH₂) - Hydrogen cooled to –253°C, where it becomes a very cold liquid with high energy density—useful for fuel and long-distance shipping. - More about this concept in the article "The Future of Aviation: How Liquid Hydrogen is Powering More-Electric Aircraft".
Boil-Off Gas (BOG) - Small amounts of hydrogen that evaporate when LH₂ absorbs heat; this gas must be handled or re-liquefied to avoid losses.
Cryogenic Temperature - Extremely low temperatures (below –150°C). LH₂ is stored at cryogenic conditions to stay in liquid form.
Centrifugal Pump - A pump that uses a spinning impeller to move liquid; in LH₂ systems, it transfers large volumes from storage tanks to ships.
Variable Speed Drive (VSD) - A device that lets a pump change its speed, reducing pressure jumps and heat generation—important for minimizing boil-off.
Fixed-Speed Pump - A pump that always runs at the same speed; simpler but creates more unwanted heat and boil-off in cryogenic systems.
Throttling Valve - A valve that controls flow by restricting it; useful but can create heat due to pressure drops, which is bad for LH₂.
Exergy Destruction - A measure of how much useful energy is “lost” due to inefficiencies—higher exergy destruction usually means more boil-off.
Boil-Off Rate (BOR) - How fast hydrogen evaporates from a tank over time, usually expressed as percent per day; lower is always better.
Ullage Space - The empty gas space at the top of a tank that allows for thermal expansion and pressure changes during LH₂ loading.
Seaborne Tank - The large insulated tanks on a hydrogen carrier ship where LH₂ is stored during transport.
Onshore Tank - The ground-based storage tanks at export terminals that hold LH₂ before it’s pumped onto ships.
Heat Ingress - Unwanted heat sneaking into cryogenic pipes or tanks, which warms LH₂ and produces boil-off.
Pressure Drop - The loss of pressure as hydrogen flows through pipes; too much pressure drop can increase temperature and boil-off.
Split-Range Control - A smart control strategy that switches between pump speed adjustment and valve control to minimize losses during transfer.
Vapor Return Line - A pipeline that sends evaporated hydrogen gas back to the onshore tank during ship loading to balance pressure.
Entropy (in this context) - A measure of system disorder; higher entropy generation during pumping or throttling means more heat and boil-off.
Halvor Aarnes Krog, David Berstad. Strategies for zero boil-off liquid hydrogen transfer: an export terminal case-study. https://doi.org/10.48550/arXiv.2512.04609
From: SINTEF.
