A concrete idea to reduce carbon emissions
-
0:01 - 0:06Concrete is the second
most used substance on earth after water, -
0:06 - 0:07and for this reason,
-
0:07 - 0:10it has a significant environmental impact.
-
0:10 - 0:16If it were a country, it would rank third
for emissions after China and USA. -
0:16 - 0:20But in fact, concrete
is an intrinsically low-impact material -
0:20 - 0:24with much lower emissions
of CO2 and energy per ton -
0:24 - 0:29than other materials like iron and steel,
even things like bricks. -
0:29 - 0:33But because of the enormous
volumes we use overall, -
0:33 - 0:38it contributes to about eight percent
of man-made CO2 emissions. -
0:38 - 0:40Concrete is an essential material.
-
0:40 - 0:42We need it to house people,
-
0:42 - 0:46to build roads, bridges and dams.
-
0:46 - 0:48So we can't do without it,
-
0:48 - 0:52but we can significantly reduce
its carbon footprint. -
0:52 - 0:54Concrete is held together by cement.
-
0:54 - 0:58And cement we use today,
called Portland cement, -
0:58 - 1:03is made by heating together a combination
of limestone and clay -
1:03 - 1:08at a temperature of 1,450 degrees Celsius.
-
1:08 - 1:11But in fact, most of the CO2 emissions
-
1:11 - 1:13come not from the heating,
-
1:13 - 1:17but from the breakdown of limestone,
which is calcium carbonate, -
1:17 - 1:22into calcium oxide
and carbon dioxide, or CO2. -
1:22 - 1:25Now we can't do without
this component altogether, -
1:25 - 1:29because nothing else is so efficient
at holding stuff together. -
1:29 - 1:32But we can replace
a large proportion of it -
1:32 - 1:36with other materials
with lighter carbon footprints. -
1:36 - 1:39Many colleagues are looking for solutions.
-
1:39 - 1:41And here in Switzerland,
-
1:41 - 1:45we have found that clays produce
very reactive materials -
1:45 - 1:47when they're calcined,
-
1:47 - 1:50that's to say heated
to around 800 degrees Celsius, -
1:50 - 1:55significantly lower than the 1,450
needed to produce cement. -
1:55 - 1:59But more importantly,
there's no CO2 emissions -
1:59 - 2:02from the decomposition of limestone.
-
2:02 - 2:05We then take this calcined clay,
-
2:05 - 2:07and we add a bit of limestone --
-
2:07 - 2:11but this time not heated,
so no CO2 emissions -- -
2:11 - 2:12and some cement,
-
2:12 - 2:19and this combination of limestone,
calcined clay and cement, we call LC3. -
2:20 - 2:22Now this LC3 here
-
2:22 - 2:26has the same properties
as Portland cement. -
2:26 - 2:30It can be produced
with the same equipment and processes -
2:30 - 2:32and used in the same way,
-
2:32 - 2:36but has up to 40 percent
lower CO2 emissions. -
2:36 - 2:42And this was demonstrated in this house
we built near Jhansi in India, -
2:42 - 2:46where we could save
more than 15 tons of CO2, -
2:46 - 2:50which was 30 to 40 percent
compared to existing materials. -
2:51 - 2:54So why isn't everybody already using LC3?
-
2:55 - 2:57Well, cement is a local material.
-
2:57 - 3:01The reason Portland cement is so pervasive
-
3:01 - 3:05is that it's produced
from the most abundant materials on Earth -
3:05 - 3:07and can be produced in India,
-
3:07 - 3:12in the United States,
in Ethiopia, almost anywhere. -
3:12 - 3:15And we have to work with people locally
-
3:15 - 3:19to find the best combination
of materials to make LC3. -
3:20 - 3:25We have already done
full-scale trials in India and Cuba. -
3:25 - 3:28In Colombia, a product
based on this technology -
3:28 - 3:30was commercialized a few months ago,
-
3:30 - 3:32and in the Ivory Coast,
-
3:32 - 3:36the full-scale plant
is being commissioned to calcine clays. -
3:36 - 3:39And many of the world's
largest cement companies -
3:39 - 3:43are looking to introduce this
in some of their plants soon. -
3:44 - 3:47So the possibility to replace
Portland cement -
3:47 - 3:49with a different material --
-
3:49 - 3:54but with the same properties,
produced in the same processes -
3:54 - 3:56and used in the same way,
-
3:56 - 3:58but with much lighter carbon footprint --
-
3:58 - 4:02is really crucial
to confront climate change -
4:02 - 4:07because it can be done fast
and it can be done on a very large scale -
4:07 - 4:09with the possibility to eliminate
-
4:09 - 4:14more than 400 million tons
of CO2 every year. -
4:15 - 4:18So we can't do without concrete,
-
4:18 - 4:22but we can do without a significant amount
of the emissions it produces. -
4:23 - 4:24Thank you.
- Title:
- A concrete idea to reduce carbon emissions
- Speaker:
- Karen Scrivener
- Description:
-
Concrete is the second most-used substance on Earth (behind water), and it's responsible for eight percent of the world's carbon footprint. Cement researcher Karen Scrivener shares the research behind a pioneering new kind of cement known as LC3, which could slash carbon emissions from this crucial building material by 40 percent, if adopted at scale.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 04:26
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