Regular viewers of the channel will know that
I'm a bit of a fan of a concept known as lateral thinking, having spent many a Saturday morning as
a kid in the early 80s watching grainy programs on TV presented by a guy called Edward de Bono
who went on to write best-selling books on the subject. I mention this because every now and
then during the course of my research work I come across a concept that exemplifies the principles
that Mr de Bono espoused. And the technology I'm focusing on today is a perfect example. To
the casual observer it may look like nothing more than an interesting metallic structure on
top of a tall building. But to Ibis Power, who are the company that installed it, it's a fully
integrated, multi-faceted system called Power Nest that provides several complementary services and
benefits to the building below, all of which can vastly reduce energy costs and potentially act
as a hub for a localized community electricity grid network. So I thought I'd better get in touch
with Ibis Power to find out a bit more about how their installation works and why it could play
a vital role in the green energy transition. Hello and welcome to Just Have a Think. Finding ways to harness the power of wind from
the top of tall buildings is a challenge that appears to be engaging the minds of developers
all over the world at the moment. You may for example have seen the recent video I
made about a US company called Aeromine, who are testing a prototype wind generation unit
on the roof of a building in Detroit, Michigan. To find out what makes this new Power Nest
concept stand out from the crowd I caught up with its inventor via Zoom recently. He's
called Dr Alexander Suma and unlike many other designers he didn't start out by thinking 'how can
I make a wind turbine work on top of a tall roof?' He engaged a much more lateral thought process
along the lines of 'how can I squeeze every ounce of available resource from an otherwise
virtually unused flat surface at high level?' Back in 2009 while training to become
an architect and civil engineer, Alexander was sitting in a classroom learning
about sustainable construction and like all good creative people he was doodling in his
notebook while he was listening to the speaker. By the end of the lecture he'd sketched out a
blueprint for an integrated rooftop wind and solar installation that, in his mind, would also need
to be beautiful and architecturally sympathetic. So that's all fine and lovely and everything but
it also has to work in the real world doesn't it? And that's where a lot of conceptual ideas
like this tend to fall by the wayside. But when Alexander started looking into the concept in more
detail he found that wind has a very high energy density and tends to flow faster the higher
you go. He also learned that allowing air to flow rapidly beneath an installation of solar
panels has a significant beneficial impact on their performance. Both those physical attributes
play a pivotal role in the design of the PowerNest system, but the lateral thinking doesn't stop
there, as we'll find out a bit later in the video. Dr Suma founded Ibis Power back in 2012 to develop
the PowerNest concept to full commercialization, and by 2016 with the help of a 1.7 million
Euro grant from the European Commission, the company had a full-scale prototype that could
be used for testing and validation. And that's a really key milestone in the journey of any
start-up because it allows potential investors to properly scrutinize the proposition to see if
it can generate a decent return on their money. A year later Ibis received some seed investment
and won permission to install the prototype unit on the top of a 10-storey residential building
in the Dutch city of Utrecht, resulting in some glowing testimonials from the people who lived
in the block below. There were no vibrations and no noise coming from the installation, and of
course the energy bills of the residents were significantly reduced. So, you know, everyone's a
winner! But that was just a single unit. Alexander knew it would be vital to make use of a full roof
space to generate as much energy as possible and realize his vision of a crowning architectural
structure blending seamlessly into a building. That first full roof installation came into
reality in 2021 as a fully integrated component of a new apartment block construction in Rotterdam,
comprising three turbines and 144 solar panels. Then just one year later the second project, twice
the size of the first, came into being on the red building that we saw at the start of the video.
That one's located in Eindhoven and it consists of four wind turbines and 296 solar panels. One
of the key insights that Alexander's architectural training revealed was the fact that most tall
modern buildings, at least here in Europe anyway, have common dimensions for their main structure.
It's typically 5.4 or 7.2 metres. So each PowerNest module is fabricated to be exactly 7.2
metres in length and width. And as any fan of dear old Henry Ford will tell you, standardization
allows for mass production which drives economy of scale and keeps the price for the end user to
a minimum. There will of course be some variations on building dimensions from time to time, so the
company also produces a range of simple steel fillets that take up any gaps and maintain the
architectural integrity of any new installation. The second key insight is the fact that most
tall buildings also have the same lining in their façade, which means Ibis can use their
standardized modules to facilitate extremely fast and safe attachment to the top of the building.
So now we're getting to the business end of the project and we can consider those other lateral
thinking innovations that I mentioned earlier. The first and perhaps most obvious step in
designing any new installation is to assess which direction the main wind flow comes from
and orientate your turbine modules to get the maximum benefit from that airflow. But perhaps
counter-intuitively, in the PowerNest design, that does not mean placing the turbines right on the
edge of the roof that's closest to that airflow. To understand that slightly confusing logic let's
just have a quick look at how air flows around a tall structure using a computer-generated model
based on the 70 metre tall Eindhoven building. Urban environments like this have lower
wind speeds and a lot of turbulence. Air is forced upwards as it hits a tall building
and then it tries to come into balance with the high level prevailing wind up here at what's
known as the shear line. As a result you get one big mess of turbulent wind flow directly
above the roof. Meanwhile down here at street level there are high pressure zones in front
and low pressure zones behind the building, causing wind nuisance to pedestrians. It's the
reason why you sometimes get a very unwelcome blast of wind in your face when you walk
around a corner in a city environment. The PowerNest system has very carefully
designed louvres at three different heights, each of which is shaped to direct the wind
towards low pressure zones that accelerate the airflow across the roof of the building,
effectively sucking air towards the exit side. And here's how that design changes the airflow in
the computer-generated fluid dynamics model. It's quite a dramatic difference isn't it? Not only is
there a huge reduction in the turbulent air above the building, but the wind nuisance at the base
of the building is also significantly reduced. And if we zoom in on the roof itself you can see
that the airflow velocity is indeed increased as it moves across the PowerNest structure. And
that's why the turbines are placed a certain distance away from the roof edge, where the air is
flowing at its fastest speed. Each turbine drives an electrical generator with a maximum capacity of
three kilowatts which it reaches at a wind speed of around 12 metres per second. The acceleration
effect that we've just looked at means it's quite common for the installation to achieve wind
speeds of around 11 or 12 metres per second, although wind flows are obviously not steady most
of the time so there will be variation there. The second Innovation is to mount the solar panels
at the top of the structure, some 4.8 metres above the roof, and to give that structure an overhang
of one metre out from the roof edge on all four sides. The weight of the whole installation
equates to between 120 and 140 kilograms per square metre, which is the equivalent of having 12
to 14 centimetres of water on a roof, and that's well within acceptable operational parameters.
The benefits of configuring the system in this way are threefold. Firstly, it leaves the roof
surface empty so that any essential equipment can be housed there as normal. Secondly, the overhang
means the PowerNest system can effectively utilize more than 100% of the surface area of the roof it
sits on, and thirdly it means that the carefully directed airflow across the roof can continuously
cool the underside of the solar panels. As we've discovered in previous videos on this channel,
solar PV doesn't work so well when it gets hot, which is ironic given that it derives
all its power from direct sunlight! By drawing that excess heat away from the
underside, the PowerNest structure squeezes between 10% and 15% more power out of each panel,
which is a significant improvement. The next piece of smart thinking is to use bifacial solar panels
and to make all the internal cladding white to maximize light reflections onto the bottom surface
of each panel. Believe it or not that single simple step of logic results in another 20 to
30 percent efficiency in solar power generation. And as a final sort of cherry on the icing on
the cake, so to speak, all future PowerNest systems will include a specially strengthened
structural rail integrated into the roof edge of the overhanging louvre frame, supported
by the triangular structure beneath. The rail will house the cabling for the building's
façade maintenance cradle. That allows full access for cleaning every window on every side of the
building, and when it's not in use the cradle will park itself neatly up on the rooftop underneath
the PowerNest. It's yet another piece of lateral thinking by the system's designer that'll do away
with the need for a roof mounted crane. And in the space where that crane would normally sit there'll
be enough room for an extra 48 solar PV panels. According to Dr Suma when you put all those
innovations together you end up with a system that achieves double the power generation
of an equivalent PV installation mounted on a similarly raised structure, and between
6 and 10 times more than a system of panels mounted directly to the roof surface. And
in terms of levelized cost of electricity, which I know you folks are always keen to hear
about, the PowerNest system comes out at between 8 and 12 cents per kilowatt hour depending on the
location based on a 25-year operating lifetime. A key goal for Ibis Power in the medium term
is to include a battery energy storage system underneath future PowerNest installations
so they can be seamlessly integrated into community power generation projects that'll be
popping up in urban environments all over the world as part of our rapid transition away from
centralized fossil fuel driven energy providers and towards a more distributed smart grid model.
The Eindhoven installation for example provides 85 percent of the tower's electricity and
Alexander Suma believes very strongly that the residents should be allowed to become
the owners of their own energy facility. Legislation didn't allow that on this project,
but that will certainly change over time. Ibis are now discussing projects from as far
south as Portugal and Spain all the way up to the countries of Scandinavia. And of course there are
high-rise buildings in sunny and windy locations over in North America and across the globe, so the
future looks extremely bright and extremely busy for this ambitious start-up. The next two projects
are due for completion in the Netherlands in the first half of 2023 and another three are slated
for installation before the end of the year. So what do you think? Do you like the
architectural design of the PowerNest system? Could you envisage something like this
on a building near you in the coming years? And what do you think about those new
community energy projects? Are they genuinely the way forward or do you think they
may turn out to be an unattainable pipe dream? As always let me know your thoughts in the
comments section below. That's it for this week though. A huge thank you, as always, to
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