You may have noticed that I'm wearing two different shoes.
It probably looks funny --
it definitely feels funny --
but I wanted to make a point.
Let's say my left shoe corresponds to a sustainable footprint,
meaning we humans consume less natural resources
than our planet can regenerate,
and emit less carbon dioxide than our forests and ocean can reabsorb.
That's a stable and healthy condition.
Today's situation is more [like] my other shoe.
It's way oversized.
At the second of August in 2017,
we have already consumed all resources
our planet can regenerate this year.
This is like spending all your money until the [eighteenth] of a month,
and then needing a credit from the bank for the rest of the time.
For sure you can do this for some months in a row,
but if you don't change your behavior,
sooner or later you will run into big problems.
We all know the devastating effects of this excessive exploitation:
global warming,
rising of the sea levels,
melting of the glaciers and polar ice,
increasingly extreme climate patterns
and more.
The enormity of this problem really frustrates me.
What frustrates me even more is that there are solutions to this,
but we keep doing things like we always did.
Today I want to share with you
how a new solar technology can contribute
to a sustainable future of buildings.
Buildings consume about 40 percent of our total energy demand,
so tackling this consumption
would significantly reduce our climate emissions.
A building designed along sustainable principle
can produce all the power it needs by itself.
To achieve this,
you first have to reduce the consumption as much as possible
by using well-insulated walls or windows for instance.
These technologies are commercially available.
Then you need energy for warm water and heating.
You can get this in a renewable way from the sun
through solar thermal installations
or from the ground and air with heat pumps.
All of these technologies are available.
Then you are left with the need for electricity.
In principle,
there are several ways to get renewable electricity,
but how many buildings do you know
which have a windmill on the roof,
or a water power plant in the garden?
Probably not so many because usually it doesn't make sense.
But the sun provides abundant energy to our roofs and façades.
The potential to harvest this energy at our buildings' surfaces is enormous.
Let's take Europe as an example.
If you would utilize all areas which have a nice orientation to the sun
and they're not overly shaded,
the power generated by photovoltaics
would correspond to about 30 percent of our total energy demand.
But today's photovoltaics have some issues.
They do offer a good cost-performance ratio,
but they aren't really flexible in terms of their design,
and this makes aesthetics a challenge.
People often imagine pictures like this
when thinking about solar cells on buildings.
This may work for solar farms,
but when you think of buildings,
of streets,
of architecture,
aesthetics does matter.
This is the reason why we don't see many solar cells on buildings today.
They just don't match.
Our team is working on a totally different solar cell technology.
It's just called organic photovoltaics,
or OPV.
The term organic describes
that the material used for light absorption
and charge transport
are mainly based on the element carbon,
and not on metals.
We utilize the mixture of a polymer
which is set up by different repeating units,
like the pearls in a pearl chain,
and a small molecule which has the shape of a football
and is called fullerene.
These two compounds are mixed and dissolved to become an ink.
And like ink,
they can be printed with simple printing techniques like slot-die coating
in a continuous roll-to-roll process on flexible substrates.
The resulting thin layer
is the active layer absorbing the energy of the sun.
This active layer is extremely effective.
You only need a layer thickness of 0.2 micrometers
to absorb the energy of the sun.
This is 100 times thinner than a human hair.
To give you another example,
take one kilogram of the basic polymer
and use it to formulate the active ink.
With this amount of ink,
you can print a solar cell the size of a complete football field.
So OPV is extremely material efficient,
which I think is a crucial thing when talking about sustainability.
After the printing process,
you can have a solar module
which could look like this ...
it looks a bit like a plastic foil,
and actually has many of its features.
It's lightweight ...
it's bendable ...
and it's semitransparent.
But it can harvest the energy of the sun outdoors
and also of this indoor light,
as you can see with this small, illuminated LED.
You can use it in its plastic form
and take advantage of its low weight and it's bendability.
The first is important when thinking about buildings in warmer regions.
Here, the roofs are not designed to bear additionally heavy loads.
They aren't designed for snow in winter for instance,
so heavy silicon solar cells cannot be used for light harvesting,
but these lightweight solar foils are very well suited.
The bendability is important
if you want to combine the solar cell with membrane architecture.
Imagine the cells of the Sydney Opera as power plants.
Alternatively, you can combine the solar foils
with conventional construction materials like glass.
Many glass façade elements contain a foil anyway
to create laminated safety glass.
It's not a big deal to add a second foil in the production process,
but then the façade element contains the solar cell
and can produce electricity.
Besides looking nice,
these integrated solar cells come along with two more important benefits.
Do you remember the solar cell attached a roof I showed before?
In this case,
we install the roof first,
and as a second layer,
the solar cell.
This is adding on your installation costs.
In the case of integrated solar cells,
at the site of construction,
only one element is installed,
being at the same time the envelope of the building
and the solar cell.
Besides saving on your installation costs,
this also saves resources
because the two functions are combined into one element.
Earlier, I've talked about optics.
I really like this solar panel --
maybe you have different taste or different design needs.
No problem.
With the printing process,
the solar cell can change its shape and design very easily.
This will give the flexibility to architects,
to planners and building owners
to integrate this electricty-producing technology as they wish.
I want to stress that this is not just happening in the labs.
It will take seven more years to get to mass adoption,
but we are at the edge of commercialization,
meaning there are several companies out there with production lines.
They are scaling up their capacities,
and so are we with the inks.
(Shoe drops)
This smaller footprint is much more comfortable.
(Laughter)
It is the right size,
the right scale.
We have to come back to the right scale when it comes to energy consumption.
And making buildings carbon-neutral is an important part here.
In Europe,
we have the goal to decarbonize our building stock until 2050.
I hope organic photovoltaics will be a big part of this.
Here are a couple of examples.
This is the first commercial installation of fully printed organic solar cells.
Commercial means that the solar cells were printed on industrial equipment.
The so-called "solar trees" were part of the German pavilion
at the World Expo in Milan in 2015.
They provided shading during the day
and electricity for the lighting in the evening.
You may wonder why this hexagonal shape was chosen for the solar cells.
Easy answer:
the architects wanted to have a specific shading pattern on the floor
and asked for it,
and then it was printed as requested.
Being far from a real product,
this free-form installation hooked the imagination of the visiting architects
much more than we expected.
This other application is closer to the projects
and applications we are targeting.
In an office building in São Paulo, Brazil,
semitransparent OPV panels are integrated into the glass façade,
serving different needs.
First, they provided shading for the meeting rooms behind.
Second, the logo of the company is displayed in an innovative way.
And of course electricity is produced,
reducing the energy footprint of the building.
This is pointing towards a future
where buildings are no longer energy consumers,
but energy providers.
I want to see solar cells seamlessly integrated
into our building shells
to be both resource-efficient and a pleasure to look at.
For roofs, silicon solar cells will often continue to be a good solution.
But to exploit the potential of all façades and other areas,
such as semitransparent areas,
curved surfaces
and shadings,
I believe organic photovoltaics can offer a significant contribution,
and they can be made in any form architects and planners will want them to.
Thank you.
(Applause)