‘From a supervisory control point of view
the entire system is transparent and
information is updated in near real-time
whether engineers and operators are
viewing the system on-site or remotely
from head office in London. For many
automation system integration projects,
providing secure networking for control
and visualisation, trending and analysis has
become as important as the actual control
over the electro-mechanical equipment on-
site and this project is no different.
Stuart Nelmes Head of Engineering
at Highview and leading the project
comments, ‘The beauty of this system is
that each component part of the process
is built using tried and tested technology,
which we know works and has established
performance parameters. The design
envelope and the application of some of
it has been developed a little to meet our
particular requirements, but it’s the way all
the different processes interact which truly
delivers the viability of the process.’
The funding has supported the design,
build and testing of this LAES technology
demonstrator on the same site as Viridor’s
Pilsworth landfill gas generation plant. ‘This
has proved to be a smart move for several
reasons’ continues Nelmes, ‘the location
was good from a planning permission point
of view, but it also has a technical benefit
in that we can use low-grade waste heat
from the GE Jenbacher generator engines
to make our gas expansion stage more
efficient.
‘Expanding the liquid air, (or Nitrogen as we
are using for this full-scale demonstrator
project) has a refrigerating effect, so
our process is more efficient if we can
counteract that by using waste heat energy
from combustion.
This is why conventional power stations
are a good potential site for the final stage
commercial installations, which is the next
step for us.’
Green credentials are off the scale compared
to other large-scale energy storage
methods; once constructed the commercial
installations will be close to environmentally
neutral, output is simply air, or in this case
inert Nitrogen, which makes up 78% of the air
anyway. Commercial installations are likely to
be used as temporary energy banks for larger
power stations, which are both slow and
expensive to turn down, or turn off.
The solution would also be very effective
for storing energy from renewable sources
such as wind turbines when there is a grid
surplus and then fed back in to the grid when
demand peaks. Fast, effective peak-lopping
is an extremely desirable function from an
energy grid management point of view and
is one reason why government funding
has been provided. It is also a reason for
considerable global commercial interest in
the project.
The project will operate for at least 1 year and
is intended to demonstrate how LAES can
provide a number of electricity grid balancing
services, including Short Term Operating
Reserve (STOR), Triad avoidance (supporting
the grid during the winter peaks) and testing
for the US regulation market. Construction on
the project began in February 2015 and it is
expected to be operational during 2016.
Mike Weeks concludes, ‘The system is not
massively complex, the main challenge we
have is that it is a development project and
by its nature some of the fine details of how
best to realise various aspects of the control
and monitoring architecture have been
worked-out as the project has progressed. We
have been able to remain flexible and help
the design team and all the suppliers come
together to achieve a harmonious working
system that allows both proof of operational
targets and room to fine-tune and learn from
it.
SO HOW EXACTLY DOES AN LAES WORK?
Air turns to liquid when refrigerated to
-196°C, which is usually achieved by a cycle
of compression, cooling and expansion, it can
then be stored in conventionally insulated,
ambient pressure vessels at very large scale.
Exposure to ambient temperatures causes
rapid re-gasification and a 700-fold expansion
in volume, which is used to drive a turbine
and create electricity.
Highview’s technology draws from
established processes from the turbo-
machinery, power generation and industrial
gas sectors. The components of Highview’s
processes can be readily adapted from large
OEMs and have proven operating life times
and performances.
WHY LIQUID AIR ENERGY STORAGE?
• No geographical constraints
• Close to environmentally neutral in
operation
• Competitive capital cost
• Long lifetime 25+ years
• Scalable to 200MW/1GWh
• Components available from a global supply
chain
• Integration of industrial low-grade waste
heat and waste cold
• Uses no scarce or toxic materials
Other partners include: GE, Heatric, BOC
and Metalcraft. KiWi Power are engaged to
commercialise the plant’s interaction with
National Grid.
LAES technology can be scaled to deliver
large-scale, long duration energy storage
from around 5MW output and 15MWh of
storage capacity to more than 200MW output
and 1.2GWh of capacity.
It can be considered as being comparable
to medium scale pumped hydro-electricity
storage, but without the geographical
restrictions of mountains and reservoirs.
When scaling up LAES technology, the system
will be modular and benefit from scale and
convenience, an advantage when locating it
to different regions and applications.
Final word goes to Highview’s CEO Gareth
Brett, “This is a breakthrough technology that
enables a new and compelling solution for
large scale, long duration energy storage.
There is nothing else available right now, that
can be deployed at this scale and duration
and at low cost. This project with Viridor will
be an invaluable demonstration for the power
sector to evaluate, implement, utilise and
capitalise on this, a milestone in Liquid Air
Energy Storage.”
www.optimal-ltd.co.uk
Issue 37 PECM
25