A Look at CO2 Reduction Technology

Climate change is currently one of the biggest challenges facing humanity.

How can we reduce carbon dioxide, one of the main causes of this problem?

In November 2021, at the COP26 conference to discuss this issue, many countries expressed their commitment to decarbonization.

It's one minute to midnight on that doomsday clock, and we need to act now.

We will reduce greenhouse gas emissions
to virtually zero by 2070.

Japan has set a goal of reducing CO2 emissions 46% by fiscal year 2030 from its fiscal 2013 levels.

We will devote our efforts to tackle this issue.

There are hopes that various state-of-the-art technologies will help achieve this goal.

Technology that captures CO2 from the atmosphere.

Technology that traps CO2 in concrete.

If this is implemented,
CO2 can be turned into a resource.

A miracle future that doesn't rely
on petroleum resources awaits us.

Today we'll look at some of Japan's carbon dioxide reduction technologies, that offer innovative approaches to the issue of carbon capture.

And later on, we'll learn about "Growing kits for value-added vegetables."

By using LED lights in the three primary colors of red, blue, and green, today's Takumi says that anyone, anywhere can grow vegetables that are nutritious and rich in taste and aroma.

Hello and welcome to Science View.

I'm Tomoko Tina Kimura.

Today we're examining the global challenge of CO2 reduction.

And, joining me as usual is Mr. David Hajime Kornhauser, Director of Kyoto University's office of Global Communications.

It's always nice to see you, Mr. Kornhauser.

Thank you for having me.

Now, abnormal weather has been occurring all over the world, and seeking measures to tackle the issue of climate change is something we can not put off.

That's right.

Scientific progress has given us many benefits, but it has also destroyed nature and caused climate change by produced a large amount of carbon dioxide.

We must use the power of science and technology to restore the global environment, such as by capturing and sequestering CO2 if possible.

So, what kind of science and technology is currently being developed in Japan to reduce CO2 emissions?

First, we'll look at one large-scale initiative.

This is an industrial area in Tomakomai City, Hokkaido.

Here, efforts are being made to trap carbon dioxide, or CO2, deep underground, far below the ocean floor.

This technology is called Carbon Dioxide Capture and Storage, or CCS.

CO2 is compressed and stored underground.

Three, two, one.

This facility uses gas containing CO2, emitted by a neighboring refinery.

The gas is transported through a pipeline to the CCS facility.

The CO2 is separated from the gas and captured, using an adsorbent called aqueous amine solution.

Next, it is compressed to 1/300th of its original volume.

Then, in a so-called "supercritical" state, where it is neither a gas nor a liquid, it is injected into rock formations 1,000 to 3,000 meters underground.

The rock formations at this depth include a storage layer, which has reservoirs suitable for storing carbon dioxide, and above that, a barrier layer, also called cap-rock.

The tightly-packed rock in the barrier layer acts as a lid to prevent the CO2 from escaping.

About three and a half years after the project began, the target of storing 300,000 tons of CO2 was achieved.

Even more results are expected going forward.

So, CO2 emitted from factories is buried deep underground.

It's a very innovative method, but how promising is it?

It is very promising and facilities are under construction all over the world.

The most suitable geological formations are those with small gaps, such as sand and volcanic ash.

It's also important that there is a barrier layer made of impermeable rock on top of it.

If CO2 in a supercritical state, with a density close to that of a liquid and a fluidity close to that of a gas, is injected into these small gaps, it can be stored effectively.

And, are there many places like that where we can store vast amounts of CO2?

Well, surveys indicate that there may be the capacity for 240 billion tons of CO2 to be stored under the seas around Japan alone, which is more than 200 years' worth of Japan's annual CO2 emissions.

So, it sounds like a good solution.

But we need to work on other approaches as well.

Next, we'll look at a technology that captures CO2 directly from the air around us.

Here in the hills of Iceland, equipment using Direct Air Capture, or DAC, has been directly extracting CO2 from the atmosphere since 2021.

Large fans draw in air and special filters adsorb CO2.

By heating it to 100 °C, the CO2 is separated and captured.

The CO2 is then dissolved in water and pumped underground.

It reacts with calcium silicate and other substances contained in basalt, and solidifies into stone.

This DAC facility has the capacity to capture 4,000 tons of CO2 per year, equivalent to the annual emissions of about 800 cars.

It's hoped that such facilities can be built in many places to reduce the amount of CO2 already in the air.

Meanwhile, a unique DAC machine has been developed in Japan.

Its distinguishing feature is its size.

This is the Hiyassy machine.
It collects CO2 at the touch of a button.

It's the size of a suitcase.

When you press the button,
air is sucked in through the hole here.

Then the air without CO2 comes out here.

Inside there is a cylinder containing an alkaline aqueous solution, and air is pumped through it.

The carbon dioxide dissolves into the aqueous solution.

The amount per machine may be small, but if it's used by people all over the world,
that will become a very large amount.

People can participate in stopping climate change
with the push of a button.

Muraki's DAC machine can capture about 5 kilograms of carbon dioxide per year, the equivalent of five thousand 500 milliliter plastic bottles.

Well, the Japanese are known for making everything small, and this man has made a compact machine that extracts CO2 from the atmosphere.

That's right.

Large-scale facilities cost a lot of money, but this compact DAC machine is more affordable, and if lots of people have one, CO2 emissions could be reduced in a more realistic way.

I think it's a great idea that aims to create a big change by bringing together lots of individual good intentions and small actions.

That's true.

Muraki's DAC machine uses an alkaline aqueous solution as an adsorbent to capture CO2 from the atmosphere.

Another typical substance that can be used as an adsorbent is amine.

And efforts are underway to improve CO2 reduction by modifying it.

The Research Institute of Innovative Technology for the Earth is located in Kyoto Prefecture.

This is where Dr. Katsunori Yogo is researching amines.

He's holding an aqueous amine solution that absorbs CO2.

What kind of substance is amine?

In this experiment, there is water on the left and aqueous amine solution on the right.

When carbon dioxide is pumped in at the same pressure, the water has many large bubbles, but the aqueous amine solution has smaller bubbles.

This shows that more carbon dioxide is being absorbed by the amine solution.

Amines typically absorb CO2 at low temperatures, and release CO2 at high temperatures.

First, the amine solution is used to absorb CO2 from the air.

Then, the amine solution is heated to release the CO2 so that it can be captured.

Yogo has modified the structure of this amine, in order to save energy when separating the CO2 from the amine solution.

Conventional absorbents need to be heated beyond
100 °C to capture high concentrations of CO2.

However, with this amine, the CO2 is released
at a much lower temperature of 60 °C.

This experimental equipment is used to check the performance of the new amine.

The pipes contain a large number of bead balls soaked with amine.

When air is pumped in...

...the concentration of CO2 goes down from 420 ppm to less than 100 ppm.

This shows that the amine is absorbing the CO2.

Then, steam at 60 °C is pumped into the amine that has absorbed the CO2.

The concentration of carbon dioxide, which was 0.04%, rises rapidly to about 95%.

This shows that the CO2 can be separated from the amine at 60 °C.

Another device was developed to reduce the energy needed in the CO2 separation process.

This rotor has a honeycomb structure, so it's easier for air to pass through it, and it has a large surface.

This makes it easier for the modified amine to adsorb CO2.

Yogo and his team plan to conduct a demonstration experiment of this system on a larger scale after 2025.

This technology might be able to capture around 550 tons of CO2 per year.

This is the same amount that a forest of about 60 hectares absorbs in a year.

That technology separates CO2 from the air in an efficient way, which is a very important factor, because if carbon capture requires a lot of energy and emits CO2 in the process, it's not worth it.

Yes, exactly.

Since the amount of carbon dioxide in the air is only about 0.04%, it is very difficult to extract, and trying to capture large amounts of it can use a lot of energy.

We need to continue to come up with new ideas and innovative approaches.

Yes, and here is another innovative idea being developed in Japan.

Let's see how it works.

Groundbreaking research has begun on new CO2 separation technology.

This is Dr. Shigenori Fujikawa of Kyushu University.

We can capture CO2 with this membrane.

He's pointing to a very thin membrane.

It's so thin that it's hard to see.

But when sprayed with water, indeed, we can see droplets on the membrane.

It's about 1/300 the thickness of food wrap.

Carbon dioxide is collected by pumping air through this membrane with a thickness of 34 nanometers.

This is a simulation of air flowing towards the membrane.

On the left, the blue dots are nitrogen.

When air is pumped in, the nitrogen is repelled by the membrane.

On the right, the red dots are carbon dioxide.

These are more compatible with the membrane so they stick to it...

and eventually, pass through it.

The main component of this membrane is silicone rubber, which is also used in things like contact lenses.

The membrane material has special CO2 selectivity.
This means only CO2 can pass through.

Kyushu University is also conducting research on converting the captured carbon dioxide into a resource.

Captured CO2 and water are put in this device.

When electricity is applied, it produces liquid ethanol.

This is the conversion unit.

By passing electricity through the metal catalysts inside, carbon dioxide and water are used as raw materials to produce compounds such as ethanol and ethylene, which can be used as resources.

By incorporating the small conversion unit and the thin membrane into one device, Fujikawa and his team are aiming to develop a versatile system

that can capture carbon dioxide and convert it into usable resources.

We want to effectively capture CO2 in places
like cities, schools, homes, and office buildings.

So this is the membrane, that captures CO2.

I don’t know if you can see it, but it’s really really thin.

I am not allowed to touch it.

Can you believe that it's 300 times thinner than kitchen wrap?

Actually, this invention was inspired by cell membranes.

You mean, the cell membranes from plants and animals?

Yes!

Plants absorb CO2 from their leaves.

Each cell is surrounded by a thin membrane, which is the ultimate filter, allowing only the necessary substances to pass through when needed.

It's amazing that they created a 34- nanometer filter by thinking about the structure of a cell membrane.

It's sure is.

CO2 is usually thought of as something that is unwanted or bad, so the fact that it can be turned into a resource represents a major shift in our way of thinking.

In fact, this is also an idea they got from plants.

Plants photosynthesize CO2, water, and light to produce energy in the form of sugar and starch.

Fujikawa thinks that if they can use this thin membrane in a DAC machine that's the size of an outdoor air conditioner unit, and that can produce resources, it will quickly become popular.

Yes, let's look forward to that.

Finally, we'll let me introduce one more very unique initiative.

When a building is demolished, a large amount of concrete waste is produced.

The idea is to trap CO2 from the air in that waste material.

First, some concrete waste is broken into small pieces.

When it is placed in water and air is pumped in, the calcium dissolved in thewater combines with CO2 to form a solution of calcium bicarbonate.

Meanwhile, concrete waste is finely ground and heated to 70 °C.

When the solution is poured onto this, calcium carbonate crystals form between the grains of concrete.

Using a microscope to look between the grains...

we can see needle-like formations, which are the crystals.

The granular waste material has solidified, and the CO2 has been trapped inside.

This approach has the benefit of using recycled concrete to trap CO2 from the air, and what's more it reduces the production of new concrete.

Cement, the material used to make concrete, needs to be heated to 1,400 °C during its production process, that emits a large amount of CO2.

Amounting to about 7% of the world's CO2 emissions.

According to estimates, if half of the concrete used in the world by 2050 is recycled concrete, it would reduce CO2 emissions by 2.1 billion tons, which is double the amount of CO2 emitted by Japan each year.

That could really make a difference.

So far today, we've seen a variety of initiatives.

Science and technology will definitely play a significant role in reducing CO2 emissions, and it's important for each of us to learn and support these efforts.

Next, onto today's Takumi / J-innovators Corner.

Yokohama has declared itself an "Innovation City" to promote new businesses.

A cafe that recently opened here is currently attracting attention due to its introduction of a new technology.

These are the "ultimate fresh vegetables" that are grown by the restaurant itself.

Such as the basil and rocket on Pasta Genovese...

The lettuce inside this freshly-made focaccia… Apart from root vegetables, this restaurant grows most of its own vegetables and flowers.

They're really delicious.

The vegetables have a rich taste.

This is Kayo Kibi, the restaurant owner.

She showed us where she grows the fresh vegetables.

On the third floor of the building, we saw a strange light...

Here it is.

Incredibly, it's an entire room for growing vegetables - a real plant factory!

More than 20 varieties of plants are grown in this narrow space.

But in fact, none of the staff here have any farming experience.

A system circulates a solution of nutrients necessary for vegetable growth, such as nitrogen and phosphoric acid, 24 hours a day.

LED lighting control provides the necessary light for the correct amount of time, depending on the growth stage.

The system's automated programs allow even amateur farmers to produce vegetables with great taste and nutritional value.

Unlike with outdoor cultivation, even amateurs can control taste
as well as achieve uniformity and quality.

The cultivation system was developed by a company in Yokohama.

Today's Takumi is President and CEO Seiichi Okazaki.

He used his knowledge of plant physiology and lighting engineering to develop the system.

We provide a "light recipe" to adjust the desired
taste or nutritional content of each plant.

This is something that can be independently-controlled.

The system is based on an automated LED control function that provides the optimum light, or "light recipe," for each plant.

Sunlight is composed of light of various wavelengths.

Red light of around 660 nanometers is absorbed by a pigment in plants called chlorophyll.

It is used for photosynthesis.

Blue light of around 450 nanometers is absorbed by pigments such as carotenoids, making stems and leaves stronger and promoting the ability to produce fruit.

This is why Okazaki used only red and blue LED lighting in the early stages of development.

However, upon further research and experimentation, he focused on one particular color: Green light.

Plants do not absorb much green light, but rather reflect it, which is why they appear green.

Because of this, green light had been considered unnecessary for plant growth.

However, Okazaki experimented with LEDs containing green light.

The results showed that a balance of green light enhances important plant nutrients, such as folic acid.

We found that the results with green light
are different than without green light.

For example, adjusting the LED light recipe
makes it possible to both increase the amount of Vitamin C,
and simultaneously reduce ammonia nitrogen,

which should not be consumed.

Our hope is that high value-added vegetables
will be able to suit individual nutrition needs.

We‘d like to help expand supply chains
that make this possible throughout the world.

The system is full of the Takumi's know-how to make the light recipes work effectively.

Relatively inexpensive "bullet-type" LEDs have high light directivity, resulting in uneven plant growth.

So the Takumi used "surface-mount type" LEDs, which cost more but can shine light at a wider angle.

Arranging the angle of the reflectors ensured that light would shine evenly on the vegetables.

The light bulbs are also arranged to provide a good balance of the three primary colors.

In addition, a water-cooled heat exchanger lies behind the LED board.

More than half of the energy used by LEDs becomes heat, which degrades components.

Using a heat exchanger to lower the temperature extends the equipment life and saves energy on air-conditioning.

How much will a plant grow
with 1 watt of power?

We paid special attention to this.

Some companies have introduced this equipment to open up new business opportunities.

This construction company in Kawasaki City is looking to enhance the value of its real estate properties and new buildings by adding the option of vegetable cultivation systems.

It's very easy to do with just this kit.

I think the appeal of this technology is growing,
and we'll continue to promote it.

This system produces "value-added vegetables."

By promoting its use, Okazaki hopes to contribute to the preservation of the global environment.

More than half of the world's population
lives in urban areas.

To reduce the burden on the environment, this kind of technology can help cities
achieve both local production and consumption.

Using such an indoor system to cultivate vegetables, it's a great solution for growing produce in the cities.

And Takumi's life recipe is really a noble way of improving the flavor and nutritional value.

So today we explored some of the latest technologies for CO2 reduction.

Mr. Kornhauser, what are your thoughts?

The ozone hole used to be one of the biggest environmental challenges facing humanity, but that problem may soon be solved thanks to worldwide efforts to reduce CFC emissions and other technological innovations.

This reminds that we should seek solutions to climate change with the same determination.

You are right. Thank you very much for joining us today, Mr. Kornhauser.

Thank you as well.

And that's all for today's Science View.

Thank you very much for joining us and please stay tuned for our next episode.