GET – GREEN EFFICIENT TECHNOLOGIES – English Language

From the research
Hydrogen
Hydrogen-island grid of Ansbach University of
Applied Sciences
Smoothing volatile power generation and delivering green power
in a predictable way
Daniel Schultheiß, Dipl.-Ing. (FH) Dieter Jarosch, Prof. Dr.-Ing. Jörg Kapischke
The greatest challenge for the
energy supply of the future lies in
the storage of large amounts of
sustainably generated electricity.
Although the expansion of renewable
energy sources is still far from
supplying countries like Germany
in a carbon neutral way, photovoltaic
and wind energy plants are
already shutting down due to temporary
overproduction. Electricity
from private rooftop solar systems
can easily be buffered in battery storage.
For solar and wind farms on a
megawatt scale, however, storage
in batteries is not a practical solution.
Ansbach University of Applied
Sciences has implemented an innovative
approach that temporarily
stores photovoltaic electricity in the
form of hydrogen gas. This allows
large amounts of electricity to be
retained almost loss-free, even over
long periods of time. The system is
designed as a self-sufficient island
grid and can be coupled with the
public power grid if required.
Description of the island grid
system
The photovoltaic system of Ansbach
University of Applied Sciences supplies
laboratories with electricity, generates
hydrogen and optionally feeds
into the public grid. Due to the easy
scalability of the system, the laboratories
can be considered representative
of the energy balance of a building,
a commercial area, a company or
a district. The building integration of
the photovoltaic system (1) with its
inverters (2) is shown in the upper
part of Fig. 1. The special feature of
the carbon dioxide-neutral system is
the combined storage system, consisting
of battery (4), fuel cell (5), electrolyzer
(6) and hydrogen storage (7).
If the labs need more electricity than
the photovoltaic system can supply,
the battery storage is discharged and
at the same time the saved hydrogen
is converted back into electricity
with the fuel cell. If this is still
not enough, additional electricity is
received from the public grid. If the
photovoltaic system produces more
electrici ty than currently demanded
in the labo ratories, the battery storage
unit is charged and the electrolyzer
produces hydrogen. If more
electricity is available than consumers,
battery storage and electrolyzer
can absorb, the surplus is supplied to
the public grid. The combination of
battery storage and hydrogen brings
together the advantages of both systems
and eliminates their disadvantages.
Battery storage systems can
take in and release large amounts
of electricity, but they only can do
this for short periods of time. Electrolyzer,
fuel cell and hydrogen storage
can store and provide electricity
over long periods of time and in large
quantities. But they are not designed
to handle peaks in generation and
consumption. The vision being pursued
with the demonstration plant
is a system of many such self-sufficient
plants that are nevertheless
networked with each other and can
Load
< 2 kW
Grid-tie inverter
3 x 3,8 kWp
(for grid supply)
H2 compressor
1 kW
H2 electrolyzer
4 kW max.
H2
Hydrogen storage
2 x 50 l, 200 bar; 1 x 87 l 14 bar
~ AC
Off-grid inverter
(Bidirectional
battery inverter)
Fuel cell
1 kW
= DC
Fig. 1: Schema photovoltaic
hydrogen island grid system
Battery capacity
48 V, 280 Ah
System components at a glance:
(1) Photovoltaic system with inverter for supplying
power to the grid (2): 38.7 kW
Switching station to island grid operation
(3) Off-grid inverter: 4.2 kW
(4) Battery storage: 8 kWh
(5) Proton-exchange membrane fuel cell:
1 kW
(6) Proton-exchange membrane electrolyzer:
4 kW, 13.8 bar
(7) Compressed gas storage station: 87 l,
13.8 bar; compressed gas storage: 50 l,
200 bar; Hydrogen compressor: 200 bar
14 GREEN EFFICIENT TECHNOLOGIES 2022