Photo: DLR (CC-BY 3.0)

On the road to hydro­gen aviation

In the BALIS project, the Ger­man Aero­space Cen­ter (DLR) is devel­op­ing the world’s first fuel cell dri­ve­train for air­craft – with a megawatt capac­i­ty. DLR is thus tak­ing anoth­er step towards enabling emis­sion-free fly­ing with hydro­gen. On 21 Jan­u­ary 2021, the Par­lia­men­tary State Sec­re­tary pre­sent­ed the fund­ing deci­sion for the BALIS project amount­ing to 26 mil­lion euros to the Fed­er­al Min­is­ter of Trans­port and Dig­i­tal Infra­struc­ture (BMVI) Stef­fen Bil­ger at a dig­i­tal event at the DLR Insti­tute of Tech­ni­cal Ther­mo­dy­nam­ics in Stuttgart.

“This decade is about turn­ing the lever and switch­ing our mobil­i­ty to low-car­bon fuels. Mobil­i­ty with hydro­gen from renew­able ener­gies plays an essen­tial role in this. Hydro­gen can be used as fuel in all modes of trans­port, includ­ing air­craft. The goal is zero-emis­sion avi­a­tion – prefer­ably with jobs and added val­ue in Ger­many, said Par­lia­men­tary State Sec­re­tary Stef­fen Bil­ger at the han­dover of the fund­ing decision.

“Whether in the air, by road and rail or at sea – DLR is one of the pio­neers in the devel­op­ment and appli­ca­tion of fuel cells and can draw on the know-how and expe­ri­ence gained from years of research. With projects such as BALIS, we will con­tin­ue to set stan­dards tomor­row: towards zero-emis­sion mobil­i­ty, which is based on hydro­gen as anoth­er pil­lar in our ener­gy sys­tem,” explained Prof. Karsten Lem­mer, Mem­ber of the DLR Exec­u­tive Board for Ener­gy and Transport.

“The BALIS project shows that hydro­gen propul­sion in avi­a­tion is real and fea­si­ble. We are thus con­tin­u­ing the suc­cess sto­ry of the Nation­al Inno­va­tion Pro­gramme for Hydro­gen and Fuel Cell Tech­nol­o­gy (NIP), with which the Nation­al Organ­i­sa­tion for Hydro­gen and Fuel Cell Tech­nol­o­gy (NOW) and the project pro­mot­er Jülich (PtJ) have been sys­tem­at­i­cal­ly devel­op­ing hydro­gen and fuel cell tech­nolo­gies from the research and devel­op­ment stage to mar­ket since 2008, using fund­ing from the Fed­er­al Min­istry of Trans­port. The NIP was and is a pil­lar of the nation­al hydro­gen strat­e­gy. Only with high­ly inno­v­a­tive tech­nolo­gies can Ger­many suc­cess­ful­ly par­tic­i­pate in a glob­al hydro­gen econ­o­my,” says Kurt-Christoph von Kno­bels­dorff, Man­ag­ing Direc­tor of NOW.

Focus: Fuel cell dri­ve­train and unique test environment

The aim of the BALIS project is to devel­op and test a fuel cell pow­er­train with an out­put of around 1.5 megawatts. This would allow a region­al air­craft with 40 to 60 seats and a range of 1,000 kilo­me­ters to be real­ized. DLR is set­ting up a test stand unique in this form. It forms the nec­es­sary over­all sys­tem, i.e. the com­plete hard­ware and the nec­es­sary infra­struc­ture: these include the fuel cell sys­tem itself, the hydro­gen tanks, the elec­tric motor as well as the con­trol and con­trol tech­nol­o­gy. This test envi­ron­ment is com­plex and at the same time very flex­i­ble. It enables research and devel­op­ment work under a wide range of frame­work con­di­tions, require­ments and guide­lines in the avi­a­tion sector.

“With BALIS, we are cre­at­ing the ener­gy con­ver­sion tech­nol­o­gy bases, devel­op­ing a first demon­stra­tion sys­tem of the 1.5 megawatt per­for­mance class and devel­op­ing an opti­mal mode of oper­a­tion. In the next step, we want to put it into use togeth­er with part­ners from sci­ence and indus­try,” explains Prof. André Thess, Direc­tor of the DLR Insti­tute of Tech­ni­cal Ther­mo­dy­nam­ics, adding: “The focus is ini­tial­ly on the use in avi­a­tion. How­ev­er, such fuel cell sys­tems can also be used in heavy goods vehi­cles, for exam­ple in large com­mer­cial vehi­cles on the road, on trains or in ships.”

Sound bar­ri­er 1.5 megawatts: New gen­er­a­tion of fuel cell systems

Most fuel cells, which are already com­mer­cial­ly avail­able, have a mod­u­lar out­put of 100 to 200 kilo­watts. In order to reach the megawatt range, how­ev­er, it is not pos­si­ble to com­bine any num­ber of small­er sys­tems. This is where tech­nol­o­gy sets lim­its. “At 1.5 megawatts, there is a ‘sound lim­it’ in terms of the archi­tec­ture and per­for­mance of today’s com­po­nents of fuel cell sys­tems,” says Prof. Josef Kallo, DLR expert on hydro­gen in avi­a­tion. “We want to cross the bor­der and at the same time bring togeth­er as few so-called high-per­for­mance fuel cell stacks as pos­si­ble. To do this, we need new approach­es and new com­po­nents, for exam­ple in the area of opti­mized cur­rent den­si­ty dis­tri­b­u­tion, volt­age lev­el, han­dling of liq­uid hydro­gen in large quan­ti­ties and cou­pling to an over­all dri­ve system.”