Every man, to live, to make his body work, needs energy.
You, the refugee in Syria, everyone needs energy.
The amount of energy we need,
I can express it in a certain quantity, it’s 25 cl of gasoline.
It’s the energy equivalent that we consume every day
and which one needs.
Society, our civilization, has developed
a set of technologies that allow us to guarantee our comfort
and who will spend a lot more energy.
On the one hand, we will produce waste;
each of us produces 2 kg of waste per day
of which 30% is organic waste,
which is the residue of the food that we have absorbed,
the food that nature has given us.
We will consume energy, 5L of oil per day, on average in Switzerland.
The problem is that we burn it and inherit CO2. 14 kg per day.
You have to imagine that if it was solid, you should, every morning,
leave with two packs of six bottles of water
and put them on the sidewalk.
Luckily, it’s gas so it goes into the atmosphere, we do not see it,
we tend to forget it too much,
but it accumulates in the atmosphere.
So we do not feel the effect but TEDx, which is there, is already observing the effect.
We thought it was important to save TEDx and find a solution
and therefore try to limit CO2 emissions.
For that, we must study the energy system.
We took Switzerland and we watched
where energy was consumed in Switzerland.
47% of Switzerland’s energy consumption is to heat us,
to illuminate us in the buildings.
This energy consumption is mainly in winter.
In winter, it’s cold, you have to heat,
and mainly in the form of heat.
Only 25% of our energy consumption
is in the form of electricity, the rest is heat.
At these 47%, I will add mobility needs
who spend 36%
and the driving force of our society, the industry, which it needs
twenty percent to work.
The square that is there is 100L of gasoline per capita,
and each red square is associated with a CO2 emission.
If we look at the city, it tends to concentrate the population.
It is said that in the future, there will be 75%
of the population who will live in cities.
If it concentrates the population, it will occupy the space.
In Geneva, every square meter
floor area also corresponds to one square meter
heated surface.
It means we are going to spend energy.
Value, if I take the Swiss average,
it’s 260 million liters a year
for the population of downtown Geneva.
It is 1 million tons of CO2 that is emitted.
The city will also produce waste,
100,000 tons of solid waste,
over 40,000 tons of organic waste,
and she has opportunities.
In Geneva, we have the lake, on the one hand,
and on the other hand, there is sunlight that illuminates all our roofs.
And if we transform the amount of energy
we get every day in liters of gas,
we see that we have 620 million liters of gasoline
who arrive on the roof every year.
We see that we have more energy available
than the energy we consume today.
So we asked the question with my colleagues
and industrial partners
to know if we could make the city really autonomous
in energy.
Autonomous energy, that means
we would like to have no more CO2 emissions,
we would no longer have to import energy,
we would also like not to have to knock down all the buildings
and rebuild them all,
we would like to use the city as it is,
and we would of course not want to ruin ourselves.
So how did we do it?
As an engineer, the first thing,
it is to look at the needs.
We do not need energy and the best thing would be not to need it.
We will look at what is the minimum amount that we need.
We will call science and thermodynamics.
This French thermodynamicist, who is Carnot,
showed that to heat a building to 21 ° C
when you have an environment at 0 ° C,
we need to buy a unit of energy
to deliver 10.
This is an important element
because it guides us and gives us motivation.
Motivation, where is it?
If I look at the amount of energy I spend in a very good boiler
which has 90% efficiency, which uses gas
so that burns and produces CO2,
I see that for the same amount of heat,
that is, 10 units, I have to buy 11 units.
The question that arises is:
why do we consume 10 times more than the minimum
that thermodynamics tells us
and, in addition, by emitting CO2?
The answer, it is in the heat pump.
What is it ?
You all have a fridge at home.
The fridge works according to the following principle:
you take electricity,
you will extract heat to cool the inside of the fridge
and you will heat your room.
The heat pump does the same thing:
she will take the heat out and, thanks to electricity,
will increase the temperature and warm you up.
Thermodynamics tells us two things,
the first is that the lower the temperature to be heated,
the less energy will have to be spent
and that’s why we recommend installing heaters
at low temperature
and not high temperature heaters.
Thermodynamics also tells us that
the higher is the temperature of the source, so of the environment,
the better.
The problem is that you have to find this source.
The city is very dense,
there are lots of buildings,
and it’s very difficult to make a single heat pump.
The idea we developed is to say:
we will cut the heat pump in half,
on one side, a heat pump
who will find the right sources of heat in the environment.
For example, if I have water in the lake,
in a river or in the ground,
I will extract this heat,
and I will transport it to where I need it,
and then I’ll use a second heat pump
which will just satisfy the temperature level I need.
You have a low temperature heater,
you will pay less than someone who has a higher temperature heater.
And the idea for transporting heat is to use CO2.
What we will do is use two tubes:
a tube with CO2 in the liquid state, a tube with CO2 in the vapor state,
we will take the steam and we will condense it and, in this way,
we will deliver heat
and use a heat pump to get to the temperature
that we need.
If now we want to cool, I can take the liquid
and I can evaporate it.
I will be able to cool my buildings directly.
As they are connected by a pipe, I can also cool
the building that needs to be cooled with the one that needs to be heated,
which allows me, finally, to recover a lot of energy.
Then, on the way, we will identify what are all the good sources
heat available, for example, the wastewater that comes out of your house
at around 20 ° C can be used to heat the buildings,
lake water, water coming out of the treatment plant or geothermal energy.
Now I have a system that will allow me to trade
the energy between the different takers.
Another important element is that I use CO2.
CO2 has a high energy density: you do not need big pipes.
We will be able to put pipes in the sidewalks
and we must not bury them because the CO2 does not freeze.
We do not have to go down very deep.
We can therefore make prefabricated sidewalks
that will transport the energy you need.
So we have a complex system that allows us, thanks to a heat pump,
to heat, which allows to be directly cooled,
which allows refrigeration in shopping centers,
for example, where you need fridges or freezers,
which also allows us to recover the heat of our waste
when we will burn them
and who uses all the opportunities offered by the environment.
The question is :
is it more efficient than the traditional system?
For that, we made an application,
it’s a district of Geneva where there are offices, housing, banks,
shops – for those who know, it’s the “Streets Basses” –
we calculated the amount of energy needed and spent today
to warm up and cool down, we see that we need 12 energy units:
10 in the form of heat and natural gas and 2 in the form of electricity.
We can also see that natural gas is mainly used in winter,
while electricity is used in the summer to cool down.
The same system with the CO2 network only needs 2 units;
we made a factor 6 in energy consumption.
We only need 16% of the amount of energy we consume today
without changing the buildings,
it is obvious that if we isolate the buildings, we will take advantage of a factor
additional multiplicative.
Of course, everyone told us: “Yes, but it will cost too much. “
And the answer is, “Yes it’s very expensive for you at the moment. “
In fact, the system we are proposing will cost less and will be profitable,
while today’s system is not profitable.
Now, I have almost reached my goal.
In fact, I have electricity that I have to bring to the system,
so not yet completely autonomous.
I have electricity that I have to bring in winter.
How do you do electricity in winter?
We can do it by importing it from the outside, but at that moment,
we will emit a lot of CO2 and I already lose a lot of profit.
I can also use new technologies, such as the combined gas cycle
which has a better efficiency and emits much less CO2
because he uses natural gas.
I can also say, “Why not use renewable energy
to train my heat pumps? “
But renewable energies are mostly available in summer,
the sun shines in summer and much less in winter.
Another type of technology can be used.
EPFL has patented a new concept that combines a fuel cell
with a gas turbine that has an electrical efficiency of 80%,
much better than the best gas station, and that separates CO2 for free.
So now I have CO2 that is in a tube,
and that’s good because I have a tube.
I have residual heat since I have 80%, I have 20% left and that falls well
since I have something to transport to my users.
I have a system that allows me to make electricity, to capture CO2,
and to do my heat needs.
But I still use fossil fuel because I use natural gas.
So we must go back to history and see the gifts of Mother Nature.
Nature has brought us two things.
On one side, we have a treasure. The treasure is something that never fills.
He’s here and we can just use it, and that’s what we do:
we take some of the treasure and burn it to make CO2.
And TedX is not very happy, actually.
What you can see is that the tank emptied
and nobody fills it.
It means that our children will have less than what we have received from our parents.
We can also look at the current account and the savings account of Nature,
renewable energies.
We have different kinds.
We have sun, wind, water and biomass.
Biomass is a little the savings account,
it is available in stored form.
I can take biomass and convert it to gas.
There are biological processes, chemical,
that convert biomass into gas.
If the process is not efficient, it will release heat,
and I have a hose that allows you to use heat,
so it will be perfect if I need heat.
And the gas, I’ll be able to use it in fuel cells.
I will also try to learn about Nature,
and if I think well, I need energy, where do I find it?
In the food that is energy that is stored.
I do not feel the variations of the sun, which varies from hour to hour
and from season to season.
How did nature realize that? She did the photosynthesis.
She took CO2 in the atmosphere,
she used photons that came from the sun, water,
and she made carbohydrates that are my food,
or who are also the trees.
We can do the same thing with a technical system:
I can take the sun, I can turn it into electricity
with photovoltaic cells, I can take them,
take CO2 and water, and make methane.
And I’m going to get CO2 that I stored,
and make methane in the liquid state that I stored.
I’m going to have a system that’s going to become a bit complex, because in the summer,
I’m going to take liquid CO2, and I’m going to make liquid methane
with the sun shining;
in winter, I will take liquid methane,
and pass it through the fuel cell
to produce the electricity I need to heat and light myself,
and I will capture the CO2,
bring it back into my pipe and convert it to liquid CO2.
If I do that, I’m going to have a system that will look super complicated
but do not forget that you have at home, every day,
several pipes coming.
You have the power cable, the internet cable,
you also have drinking water and wastewater from your home,
so adding a pipe is not necessarily that complicated.
We have a system that allows us to heat, cool, refrigerate,
to value all our waste
and store the solar energy that we will produce on all our roofs,
in summer, to make it available in winter.
If I do that, I have a system that will become fully autonomous in energy.
Before I had a system that burned a lot of energy
to meet my needs, which emitted a lot of CO2 and emptied my treasure.
Today, with an investment, I have to install a new infrastructure
with heat pumps, fuel cells and storage,
I will be able to satisfy the same needs,
I did not change the buildings, I did not change your comfort,
you will always have the same temperature in all your rooms,
you’ll just have solar panels on the roof,
fuel cells that will produce electricity based on methane
which was produced during the summer.
You will recover the heat of the hot water that you sent to the sewer
because you will be able to use it in heat pumps,
you will recover the energy of your waste, and in the end,
in fact, you will be exporting electricity to order.
That is, you can decide when you export it,
when you have too much and it will be stored as methane.
For the little story,
the amount of storage needed is ten times smaller
that the amount of tanks needed that are in all the buildings
if you heated everything with fuel oil.
And that will be my conclusion.
TEDx can tell us thank you.
Because if you are able to transform the city
in a net producer of electricity without CO2 emission,
he may have a chance to find another, more secure block of ice.
Thank you very much.
(Applause)
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