Brulic Ltd ZAS0003

Written evidence submitted by James Pitman, CEO, BRULIC Ltd

Summary

• Aircraft carrying all their fuel, of whatever type, for medium and long-haul flights is highly inefficient and one of the simplest ways to accelerate the transition to net zero is to refuel those flights in the air to save fuel and therefore radically reduce emissions.
• In-Flight Refuelling is a highly mature concept, long used by the military and search and rescue, but only now adapted by BRULIC for potential safe use by commercial flights. 
• The theoretical savings of In-Flight Refuelling are well documented and on a 9,000 nm flight can amount to over 60% fuel (and therefore emissions) savings.
• The greater the length of flight, the greater the potential proportional savings from In-Flight Refuelling, which is key to address the ‘difficult to abate’ long haul flights segment, which accounts for more than half of the emissions in the aviation industry.
• We believe the BRULIC In-Flight Refuelling technology could be retrofitted to the existing fleet offering a fast route to emissions reductions and a faster transition to Net Zero. 
• In-Flight Refuelling also offers the opportunity to refuel hydrogen or electrically powered aircraft in flight as well, radically extending their range, enhancing the economics of net zero aviation and potentially changing the long-term design of the aircraft themselves.
• The reduction in fuel required generates substantial cost savings, on top of the emissions reductions and is therefore an attractive alternative to depressing demand with an highly attractive investment profile.
• Recommendation is for a detailed feasibility study into In-Flight Refuelling for SAF and liquid hydrogen to be undertaken by the Jet Zero Council, covering commercial and emissions benefits and building on the existing research already completed.

1.      BRULIC Ltd is a UK owned and controlled start-up company holding IP for a novel way to harness In-Flight Refuelling for commercial aircraft.  The concept builds on several studies of the theoretical savings that would be possible, most notably a      €3 M EU funded study in 2015 (https://cordis.europa.eu/docs/results/284/284741/final1-recreate-final-report-publishable-summary.pdf ) and work by Dr Raj Nangia, (for example https://aerospace-europe.eu/media/books/CEAS2015_257.pdf ).  None of the research developed a concept of the technology for In-Flight Refuelling that was appropriate for commercial aircraft, and which solved issues of safety, cost and practicability.  We believe that BRULIC technology does solve those issues and can therefore potentially radically accelerate the reduction of emissions by the aviation industry and thus more rapidly achieve the transition to Net Zero aviation with significant benefits for all stakeholders.

2.      Long haul commercial aircraft typically take off with 50% of their weight in fuel and a significant proportion of that fuel is expended in gaining operational altitude (can be 10-15% depending on length of flight).  Some long-haul aircraft land to refuel and for other operational efficiency reasons, but this is inefficient due to diversion from an optimal flight path and the expenditure of fuel required for take-off, plus delivering a sub-optimal experience for passengers, who generally prefer direct flights minimising time expended in point-to-point travel.

3.      All novel fuels are likely to be more expensive than jet kerosene, even with carbon taxes and incentives added.  A recent EU report expects SAF to be 3-6 times more expensive than current jet kerosene (https://ec.europa.eu/info/sites/default/files/refueleu_aviation_-_sustainable_aviation_fuels.pdf ) with prices for liquid hydrogen unclear as yet.  For both these novel power sources there are big questions around production capacity growth, investment requirements for that production capacity and the opportunity costs associated with the energy sources required- such as renewable electricity for green hydrogen or the biomass for SAF, which could conflict with food production and/or other transport power source requirements.   All this argues strongly for more efficient use of the fuel in aircraft and the minimisation of the expenditure of fuel to carry a fuel supply on board that could be optimally supplied en route, as any motorist on a long journey well knows. 

4.      The reductions in emissions associated with materially reduced requirements for jet kerosene or SAF is obvious and well documented elsewhere.  However, there are other material environmental benefits that would accrue from use of In-Flight Refuelling.  The reduction in Maximum Take Off Weight (MTOW) for aircraft using In-Flight Refuelling (they only need to carry fuel sufficient to fly to the next refuelling rendezvous with a refuelling tanker en route, plus some safety fuel) means that they can take off with reduced power, reducing noise and emissions at the departure airport and because of reduced MTOW they could operate from shorter runways, opening up many regional airports for point-to-point international flights.  This has the advantage of dispersing flights and minimising congestion plus reducing ground travel to hubs and potentially widening participation by offering flight destinations from a wider range of regions. There is also an economic benefit in driving passenger/tourist expenditure into the regions, thus driving the levelling-up agenda.  Reduced MTOW also mitigates climate change temperature rises in terms of reduced lift due to air density reductions.

5.      For the aviation industry there are obvious benefits from fuel cost savings and if, as we believe, the technology can be retrofitted to the existing fleet then it offers a much quicker and cheaper route to emissions abatement than new aircraft models.  New aircraft models require huge investment by both airlines and OEMs and with a c.20 year replacement cycle, would be introduced relatively slowly.  Cost savings from fuel use reduction from harnessing In-Flight Refuelling would also allow airlines to rebuild their balance sheets post Covid much quicker and therefore accelerate investment in radically new aircraft designs (liquid hydrogen etc) in the future.  As the life of an aircraft is often dependent on the number of pressurisation/depressurisation cycles (from taking off and landing), In-Flight Refuelling could increase airframe life by 50% by eliminating refuelling stops and also reduce maintenance and servicing costs.  Furthermore, by harnessing fewer aircraft models to cover more routes (by using In-Flight Refuelling), there are operational savings efficiencies in training, servicing, availability, inter-operability etc.

6.      The key challenges for In-Flight Refuelling using the existing technology used by the military are:

a)      Receiver aircraft always flies behind the tanker, therefore suffering wake turbulence

b)      Receiver aircraft and tanker are typically in close proximity (10-15 m for boom and c. 30m for probe and drogue) and obviously both flying at high speed, with associated safety risks

c)      Both probe and drogue and boom technologies require huge skill and constant re-training for the receiver aircraft pilots, who are required to manoeuvre their aircraft to connect with the tanker

d)      Training and re-training of receiver aircrew is very costly

For all the above reasons the existing technology is not compatible with commercial flights.

BRULIC technology addresses all these issues:

-    Commercial flight crew are not directly involved in the refuelling operation and therefore do not need to undertake specialist training and re-training.

-    The whole procedure is managed by the specialist tanker crew controlling a steerable drogue on a cable (an animated video of the procedure is at: https://www.brulicltd.com/aviation/refuellingvideo/ ) which draws the refuelling hose out from the tanker to connect to the receiver aircraft in front of it.

-    Tanker is aft of the receiver aircraft, minimising wake turbulence and risk to passengers and crew (this is the inverse of current IFR technology), indeed passengers would be likely to be unaware of the procedure

-    The separation between tanker and receiver can be significant (only limited by the hose drum capacity on the tanker and the physical characteristics of the fuel hose) to facilitate safety accreditation and certification

-     Minimal equipment is carried on the receiver aircraft (we have developed an integrated In-flight refuelling pod in the dimensions of a standard Unit Load Device (ULD) for retro-fitting to the current fleet)

7.      The scale of the emissions savings and fuel savings achievable through In-Flight Refuelling (IFR) vary by length of flight, with the greatest for long haul, less for medium haul and negligible savings for short haul.  The EU report mentioned in para. 1 estimated the sector fuel savings to be in the order of 11-23% net of fuel required to power the refuelling tankers.  The theoretical savings derived from Dr Raj Nangia’s work (https://aerospace-europe.eu/media/books/CEAS2015_257.pdf ) show:

*Modelling is theoretical for an aircraft with 2500nm range and carrying 250 passengers

**at 9.57 Kg CO2/gallon Jet Fuel (https://www.eia.gov/environment/emissions/co2_vol_mass.php )

8.      This illustrates the potential to reduce emissions in the hardest to abate long haul sectors.  It is hard to think of an aviation operational efficiency with an emissions abatement potential of anywhere near these figures.  The BRULIC innovation harnesses existing mature technologies with innovative elements integrated, so is not, as yet, proven technology in an holistic sense, but with the maturity and expertise already in place from existing In-Flight Refuelling models, we believe that implementation could be relatively rapid and certainly in comparison to other innovations with similar scale of potential emissions savings.  As an aside, In-Flight Refuelling is now 100 years old, with the first patents granted in 1921.  It is probably about time it was harnessed for commercial aviation!

9.      The above figures illustrate the scale of fuel savings, but the operational requirements and costs of tanker refuelling are not illustrated.  Dr Nangia’s assessment is that each sortie of the tanker could refuel 3-4 flights, but this would require careful scheduling and air traffic control.  This emphasises the holistic nature of the concept and the need for a wide range of stakeholders to be involved and to give support for such an initiative.  We estimate that at a cost of $10K per block hour for tanker operations, the cost savings for Jet A kerosene at today’s prices would reduce the savings potential on a 9K nm flight from 54% fuel saved to c. 41% fuel cost saved, including the cost of tanker servicing.   Self-evidently the greater the cost of fuel/SAF, the greater the potential for cost savings on top of the emissions savings.

10.  In-Flight Refuelling of aircraft with liquid Hydrogen or electric power replenishment is less mature and is not yet, as far as we are aware, operationalised.  However, we posit that the principles are the same and instead of a fuel hose, an electrical power cable could be connected between the tanker and receiver with power potentially generated in real time on the tanker via an electric generator (fuelled by H2, SAF or even in the future a small nuclear reactor) rather than power transfer from electrical power storage systems.  Pumping liquid hydrogen from a tanker to refuel an aircraft powered by liquid hydrogen has more complexities and risk than kerosene fuel, but the technology for liquid hydrogen refuelling for road vehicles is already developing fast and although there are significant challenges to be overcome, should be applicable to aircraft in the future.

11.  The potential benefits of integrating In-Flight Refuelling into the design of the new generation of aircraft, fuelled with liquid hydrogen, for instance, are potentially significant.  One of the major challenges with liquid hydrogen (H2) is the power density by volume challenge.  Although H2 is power dense by weight (unlike electrical power storage systems) the volume required for storage is significant.  There is therefore a significant trade off with passenger capacity and payload and this is what currently restricts the conceptual H2 powered aircraft to short haul only.  If In-Flight Refuelling was harnessed, this trade off changes and extends the range of the aircraft, so that it could cover short, medium and long-haul flights.  Furthermore, a single H2 aircraft model able to service all these segments would make the ROI (return on investment) case far more attractive and would accelerate development and adoption (common operating efficiencies for airline operators)- and of course reduce the total requirement for green H2 vs other operating models.

12.  There are many challenges to the adoption of In-Flight Refuelling as a novel process/technology.  Regulatory authorities need to be convinced of its safety and a multitude of operational issues around tankers, traffic control etc must all be resolved.  As of date, there has been little enthusiasm from sector specialists, due to an attitude towards In-Flight Refuelling derived from knowledge of military technologies, which as we have shown previously are wholly inappropriate.  Enthusiasm for SAF is very high because little change is required to existing aviation infrastructure, although the challenges of cost and supply could be very significant, whereas adoption of In-Flight Refuelling would require some major operational changes and yet the opportunity for emissions savings are very much greater.

13.  Early adoption of In-flight Refuelling would most likely be on long haul flights eg Europe to East Asia or Europe to West Coast US where sufficient density of traffic would justify establishment of tanker operating locations at appropriate points to service the early adopter flights.  An advantage of the BRULIC technology is that existing refuelling tankers could be adapted to service civilian as well as military aircraft because the refuelling of military aircraft takes place exclusively aft of the tanker and with the BRULIC technology would be forward of the tanker for civilian aircraft, but with both processes sharing access to common fuel storage tanks on board the tanker (Airbus MRTT tanker can offload c. 110 Klbs fuel per mission).  In the longer term this inter-operability would be valuable to military operations (outside of contested zones) by providing access to tanker refuelling capacity more cost effectively.

14.  If the sector is to harness In-Flight Refuelling as a mechanism to drive emissions down fast, then authorities such as CAA, ICAO, ATI, Jet Zero Council need to consider it more open-mindedly.  Despite the clear opportunities illustrated above, there has been little attempt to innovate in the In-Flight Refuelling industry to adapt their technology for commercial use or indeed assess the new proposals that BRULIC has made.  BRULIC recommends that a detailed feasibility study be undertaken by Jet Zero Council, together with other stakeholders, to assess the emissions and commercial benefits of In-Flight Refuelling not only for SAF but also for liquid hydrogen, building on the significant theoretical research already completed and the existing successful practical application of In-Flight Refuelling in other aviation segments.

August 2021