My work is to produce energy from plants.
And that’s what we are going to do today.
Also, I can describe to you how to use your
household plant to produce some electricity,
with simple ingredients that you should have
at home.
You did hear that right. Dr Fabian Meder,
who’s a scientist working at the
Italian Institute for Technology, is showing me how to generate electricity from a houseplant.
His laboratory's shut because
of coronavirus, so he’s using a webcam in
his bedroom to demonstrate.
So here I have a plant of course.
What kind of plant is it?
That’s a rhododendron plant, we are going
to touch the plant leaf surface and they shouldn’t
break too easily. Here I have the cable, it’s
a very thin cable. And that’s it basically. Some LEDs.
Some LED lightbulbs?
Exactly.
Let’s start, so first of all you should
connect a small needle into the inner plant
tissue, just punch it into the bark….
He drives a nail into the stem of the plant,
ties that to the piece of wire and then connects
the wire to a row of green LEDs. The LEDs
are stuck to the underside of a strip of silicone
rubber. He takes the silicone and starts slapping
it against one of the leaves of the plant.
I can see it, the lights
are lighting up! That’s amazing!
Welcome to People Fixing the World from the
BBC World Service.
This is the programme that looks at unusual
solutions to some of the world’s problems.
I’m Daniel Gordon and in this edition, I’m
looking at the power of nature.
We’re not even halfway through 2020 and
it’s already predicted by some scientists
to be one of the hottest years since records
began, if not the hottest. So the need to
develop green sources of energy that could
help tackle climate change is more urgent
than ever.
Could the answer be, well, everywhere?
There are natural supplies of energy all around
us. Some of them have already been put to
use and most people will already be familiar
with wind and solar power.
But this programme’s not about them. It’s
about the energy that’s in places you might
not think of like the heat trapped in
rocks nearly 5 km underground.
And at all the points where rivers run
into the sea, and fresh water meets salty water.
It turns out, it even grows on plants and trees.
I’m going to be meeting some of the people
who hope that eventually, they can harvest
it and turn it into electricity, so we can
reduce our reliance on the fossil fuels that
are driving global warming.
One of those people is Fabian Meder. He’s the man
who you heard a moment ago, using a pot plant
to generate electricity.
I mean surely people must think you're crazy,
you come up with this idea that you’re going
to generate electricity from trees. I mean,
it’s nuts isn’t it?
Let’s say, at the beginning, I myself didn’t
believe that this works. Doing the first experiments
in the laboratory, I could not believe the
signal is true.
I thought there must be a
mistake somewhere. But at the end it was true.
So, starting convincing myself, then I managed
to convince also some of my friends, my family,
whatever. But still they think we are crazy.
This is still part of a scientist’s life
I guess anyway.
Dr Meder is part of a team of researchers
who found out that this technique for generating
electricity works on the leaves of any plant
or tree that grows on dry land — it’s not
just rhodendrons in pots on your balcony.
It’s a natural phenomenon that occurs every
time the wind blows hard enough to make two
leaves touch each other.
This is the same mechanism that you might
know from the rubber balloon, which you rub
on your clothes, or on your hair, and it creates
a static electricity on the surface.
Like so many scientific breakthroughs, Dr
Meder’s team came across it by chance, while
they were working on another project.
The original idea is to produce energy from
an artificial bush moved by wind. And the
idea is also to use the wind generated by
cars along the motorway. The principle is
the same, but in the original idea all was
artificial so there were no natural leaves.
That’s Dr Meder’s colleague, Dr Barbara
Mazzolai.
And it was when she was working on that artificial
bush, she began to experiment on real plants.
That’s when she realised they were, effectively,
natural electrical generators.
If two natural leaves are in contact, they
produce energy in fact, but the quantity of
energy that’s produced in this way is very
low. We cannot power any artificial devices.
The solution she and her colleagues came up
with was simple — to add artificial leaves
to the tree made of conductive materials like
silicone rubber.
These materials are very good when they are
in contact with the natural leaves. So our
idea is to create a hybrid tree this is the
goal to have several artificial natural leaves
that are moved by wind, and so in this way
we can extract the energy from these leaves.
How is this different to a wind turbine? You
could just put up a wind turbine that also
takes advantage of the wind and produces a
lot more power.
It’s different because the idea is to use
a natural structure that are trees in fact
so we don’t need to add some big infrastructure
in the environment.
But on a typical tree there must be thousands
of leaves, that’s a massive job isn’t it?
Absolutely so yes we need time to in some
way put the artificial leaves on the natural
one but is still convenient.
And presumably you have to be careful about
the plants that you choose, they’ve got
to be evergreen trees right that you pick
otherwise in autumn you’ve got no electricity.
Absolutely at least you don’t have in winter
so this is very important.
Before the coronavirus lockdown brought everything
to a stop, the team at IIT managed to test
a tree in a wind tunnel with seven artificial
leaves attached to it - and each of them lit
up 150 LEDs.
But even if they manage to hook up every leaf
in a whole tree, the amount of energy they
can produce would still be relatively small.
So realistically, they're hoping to use this system
to generate just enough power to run the lights
in a park, say, or the sensors used in agriculture
to monitor the amount of heat and light that
crops receive.
There’s still one big unanswered question
though - we don’t know if trees use this
energy for something themselves and what effect
taking it away could have on them.
And by the way, I did have a go at slapping a plant myself.
But the lights just wouldn’t come on for me.
I’m not sure if the plant will be happy
about that.
Now it’s time for our second natural power
source. One of the issues with growing electricity
on trees is, something that affects lots of
renewable energy sources — if the conditions
aren’t right, they don’t work.
So how about this.
THERE IS STILL ONE LITTLE-KNOWN, YET POWERFUL
OPTION, OSMOSIS, ALSO KNOWN AS BLUE ENERGY.
That’s a promotional video made by a Swiss
research laboratory, which is one of the many
organisations around the world trying to develop
so-called blue energy.
THIS IS A VERY PROMISING SOURCE OF RENEWABLE
ENERGY. SOLAR PANELS ONLY WORK WHEN THE SUN
SHINES, WIND TURBINES WHEN THE WIND BLOWS.
BUT OSMOSIS CAN BE USED IN RIVER ESTUARIES,
WHERE FRESH WATER MEETS SEA WATER, AND COULD
POTENTIALLY WORK ALL THE TIME.
The fresh river water obviously gets more
and more salty until eventually it turns into
sea water. Scientists know that this very
simple chemical change releases energy.
What they’re working out now is the best
way to harness it and turn it into a viable
electricity supply.
As you’re about to hear, the technique is
still being refined — but the basic idea
is to divert the water into a power plant
and let it mix there under controlled conditions.
The salt water and the fresh water are pumped
in separately.
They’re allowed to mix in a huge container
inside, which has a membrane - like a very
fine sheet - strung across the middle of it
— right at the point where the two types
of water meet.
And it’s the membrane that’s used to generate
electricity.
I spoke to two of the researchers who’ve
been trying to develop the idea.
Hello my name is Martina Lihter.
Hey, my name is Michal Macha.
They work at the EPFL laboratory in Switzerland.
It’s quite stunning that it’s possible
to produce the energy from these kind of sources.
It’s a very renewable source of energy,
it doesn't pollute, it doesn’t produce CO2.
And basically it could be available 24/7.
It sounds a bit too good to be true.
Why has nobody thought to capitalise on this before?
Actually, this idea exists already for like
70 years. And the people were trying to to
extract this energy in different ways.
In fact it was in 2009 that the world’s
first osmotic power plant opened in Norway,
run by Statkraft.
The world needs more energy… pure energy.
And here’s their promo video
If fresh water and salt water are separated
by a membrane, the fresh water will travel
through the membrane to equal out the difference
in salinity. This will increase the pressure
on the seawater side, corresponding to lifting
the water 120 metres. The pressurised water
can be used to run a turbine that generates
electricity.
But that plant closed down after four years
because its operators couldn’t produce electricity
cheaply enough to make it worthwhile.
At the lab where Martina and Michal are based,
they’ve gone back to the drawing board,
using a different technique to the one tried
in Norway.
They’ve adapted the membrane that separates
the salt water and fresh water.
Instead of causing pressure to build up
that then drives a turbine, as the water mixes,
the membrane acts as a kind of filter that
separates out the ions — the tiny particles
that make up the salt in the water -- into
positive and negative ones.
This kind of membrane should prevent one type
of ion, for example positively charged ions,
not to go through to the other side, while
only the negatively-charged ions will be able
to pass. In this way, you will have a net
charge. So you can extract this, we call it
osmotic current, which can be converted into electrical
current.
And the crucial thing is to find the right
material to make the membrane with.
The membrane needs to be able to carry an electrical
charge, be tough enough that it can stay intact
while holes are drilled all over its surface
to allow the water to pass through, and also
be very thin so it won’t slow down the flow
of water.
The material they’ve come up with is a substance
called molybdenum disulphide. It occurs naturally
in crystals and they’ve managed to produce
a layer of it that’s just three atoms thick.
And whilst it might have a fancy chemical
name, the first method they tried to file
it down until it was almost invisible involved
some full-on low tech.
How do you make something so thin? How do
you manage to thin it down that much?
We can exfoliate it, we thin it down to very
thin size for example you can use the ordinary
sticky tape.
Actual sticky tape?
Yes, yes, exactly. You press the sticky tape
to the crystal. Then you peel it off. And
then you will see that you have some pieces
of this material on the sticky tape and then
by folding the sticky tape to each other and
unfolding and doing this many many times you
can extract these very thin layers.
Since then, the team has managed to reproduce
the same material in the lab, which means
it’s easier to make large sheets of it.
They’ve also found that shining a light
on the membrane as t he fluids mixed could
boost energy production.
But so far they’ve only tested their system
under laboratory conditions — and although
they’ve proved it works, they’ve
managed to produce just a tiny amount of electricity,
using a small piece of membrane with
a single, miniscule hole in it, called a nanopore
— just big enough to allow a salt ion to
pass through.
Michal admits that there’s a long way to
go before this can be scaled up.
We’ve made only one pore in this nanomaterial. From that we’ve estimated how much power
we can get if we made a lot of pores. So you
can imagine we have a super-thin film, suspended
between one water and another water reservoirs,
and now you want to make a lot of holes in
it, and make it even more fragile than it
already is. It’s a challenge. We are taking
the physics to extremes, yes.
There’s still a lot of work to do to turn
this tiny patch of membrane into a fully functioning
power station - pumping the river and sea
water to the powerstation takes energy, for
example, and then before you can use it you have to filter the water.
Natural waters are filled with particles and
stuff that you don't want to have on your
membrane because they clog the membrane and
can destroy the membrane.
So this is a huge art by itself to figure
out how to overcome this. You can either try
to have some design tricks or you can try
to make your membranes basically so efficient
that, well you don't have to worry about the
energy losses.
With so much still to work out, it sounds
like it’s going to be quite some time until
blue energy is able to live up to its potential
- if it ever does.
Meanwhile,
under our feet, there’s another potential
power supply. It’s absolutely vast and pretty
much inexhaustible.
Geothermal energy - using heat from the molten
core of the earth as a power source - is nothing
new. There are loads of geothermal plants
running in more than 20 countries around the
world which use hot rock underground to produce
steam, which in turn spins turbines to create
electricity. Kenya, for example, already gets
a quarter of its energy from underground.
Standard geothermal wells are between 1.5
and 2.5km below the surface and the rocks there
are normally no hotter than 350 degrees C [Celsius].
But there’s a race to go deeper and hotter
with something called Deep Geothermal. One
of the people involved is Gudmundur Omar Fridleifsson
at the Iceland Deep Drilling Project. He’s
dug down to double that and says the rewards
are potentially a lot bigger.
Our mission is to drill a very deep hole into
very hot rocks. We have set our target to
rocks that are below 3 km down to approximately
5 km. The rock temperature we are after is
about 400 degrees centigrade and up to 600
degrees. It costs about three times more than
a conventional well. But if we can utilise
it, tame it shall we say, control it, then
we can expect to get 10 times more energy
out of each drill hole. So in the long run
you will earn from it.
But it also comes with bigger risks. Like
what happened when they were digging their
first well.
At 2.1 km, we hit magma unexpectedly, which
was 900 degrees hot — and that was some
experience, I can tell you. We got a 
kick from the magma. The drill string which was
down in the hole kicked upwards.
What you're calling a kick -  what does that feel like?
It is just like somebody down there in the
ground is pushing up against you.
They stopped drilling and moved to another well instead but then the same thing happened again. On the third attempt, they drilled into magma
yet again — but this time, they decided to
just keep going.
We drilled the third time, to the same depth,
got the kick, but were very obstinate,
stay put, just pumping water through the drill bit
and say ‘we shall tame you.’ And we put
down some pipes and just cemented the pipe
to the inner casing, shall we say. And half a year after the drilling we started producing from the well.
We did some testing for almost three years until
2012, we learned a lot about how to deal with
magma at shallow depth in high temperature fields.
After that, the magma well was sealed off
and the team moved on to the second
phase of the project - a 4.5 kilometre deep
hole that was completed in 2017.
How long does it take to dig that deep beneath
the earth?
168 days, to be exact.
Is that continuously? 24 hours?
Yes.
That’s one long drill bit — that’s
not something you can store in your shed?
This is a technique that is well known in the oil industry and the drilling business, there was nothing special about it.
Why wasn't this tried before?
Because people were not convinced that they
could control it. That's very hot fluid
in a natural environment.
And what makes you think you can now?
Better technique and more curiosity.
I should say that although all geothermal
energy is very green, some greenhouse gasses
can escape from underground. Still, the climate
footprint is much, much lower than for fossil
fuels.
The important thing for Gudmundur is that
the Iceland Deep Drilling Project has demonstrated
that it is possible to handle the extreme
conditions deep underground.
An earlier attempt to dig to this kind of
depth in Switzerland had to be abandoned after
it triggered an earthquake — and the geologist
behind it was prosecuted for damaging property.
But, as you might have picked up, Gudmundur
is not someone who gets discouraged easily
— and he says he’s not worried.
We would not be concerned about such a small
earthquake. But people who are not used to
earthquakes of this magnitude — especially
if they are in cities, you can feel it and people are scared of it, it’s
very uncomfortable. So I can understand the
fear. But in our case, we are drilling in
an uninhabited area, 15km to the nearest village,
so these earthquakes would not be felt at all.
Iceland already gets a lot of its energy from
traditional geothermal sources because
it lies above a ridge where two tectonic plates
meet — so there’s more heat closer to
the surface than in other places.
But it’s not the only country that sits
above geological fault lines — and so in
theory, deep geothermal wells like the one
Gudmundur’s been working on could also be
constructed in places like Indonesia, Turkey,
Italy and Kenya — all of which already use
conventional geothermal energy.
So far we are just in research and development.
So we have not yet reached that stage to make
it economical, so it’s a long-term research
project that could have very high reward or return.
That’s it from People Fixing the World this
week.
We love getting your emails, so please get
in touch if you’ve seen projects you think
we should cover, or you just want to say hello.
The email is peoplefixingtheworld@bbc.co.uk
