29 August 2013

New process can trap carbon as stone for construction, paving, and more

So you’ve designed the perfect carbon capture process, cheap and easily installed in everything from coal power plants to car exhaust systems. Everything works perfectly, and not a single hydrocarbon escapes its net. Congratulations, you’ve solved one of humanity’s most pressing problems — but you’ve also created another. All that carbon may not be in the air, but it still exists. What do we do with the solid carbon byproducts in our quest to save the atmosphere?

Historically, the options have been limited and universally unattractive. Some carbon byproducts get pumped below ground to seep into the cracks of rock layers deep below the surface, a process that we already know causes huge chemical changes in the rock. Other companies opt to dispose of their carbon capture wastes by pumping it into the ocean, where pressures below a certain depth will cause it to form a thick slurry that falls to coat the ocean floor. Any large-scale storage option will be ultimately unsustainable, which leads to a fairly obvious question: can’t we figure out a way to make these carbon-rich wastes work for us?

An international group based out of the University of Newcastle has a tantalizing answer: perhaps we could build things out of it. A new $9 million grant will be applied toward this goal, expanding lab-scale successes to possible industrial uses. The process mimics one of the major geological carbon sinks ongoing in the Earth itself, the sequestration of CO2 as rocks of neutral carbonate. By forming these rocks (which can basically be thought of as limestone) into bricks, they hope to make newly built structures into monuments to the fight against climate change. The team will test the brand new process in a mineral carbonation research pilot plant to be built at the University of Newcastle, planned to open in 2017.

This Masonic temple in Detroit is made almost entirely from limestone.

Scientists have been aware of this process for some time, the reaction of gaseous CO2 with low grade minerals such as magnesium and calcium silicate. The problem has always been that the process was highly energy-inefficient. That’s why the process goes so slowly in natural geological systems, but new research has dramatically lowered the energy threshold. Newcastle is the same university that this year made the production of calcium carbonates “a thousand times cheaper” through the use of nickel nanoparticles.

Building whole structures out of bricks of synthetic carbonate should be fairly familiar to the building industry, since blocks of natural limestone are one of the oldest and most widely used building materials in human history. It has been used in everything from the Egyptian Pyramids to the British Parliament buildings, and has proved itself as a versatile and durable material. The researchers also want to see their rocks used as paving stones. There’s no way to tell how synthetic carbonate bricks will measure up in terms of cost per ton, but the researchers are hoping this plant will let them develop the process into a price-competitive option.

Global carbon emissions have spiked dramatically in the last twenty years, with several developing countries springing forward into affluence and mass power consumption. Worldwide annual emissions now sit around 30 billion tons. Though it’s arguably already necessary to store a larger proportion of this carbon, that fact will become undeniable over the coming decades — or perhaps even less than that. Linking wastes to separate production cycles is the only long-term sustainable solution. As Newcastle professor Bodgan Dlugogorski says, “we are permanently transforming CO2, not just storing it underground.”

Making carbon emissions into salable products isn’t just useful as a way to edge out harmful storage techniques. It’s also useful as a source of monetary incentives for companies to keep plants updated with the latest in capture technology. If the energy industry saw every molecule of CO2 released into the air as money lost, we would not today see about half of new power plants built with outdated and ineffective capture tech. Whether it’s through this technique or some other, using the innovative abilities of the private sector to increase their own bottom lines through efficient carbon capture could be the best way to advance not just carbon capture technology, but its actual utilization in real world.

Now read: “Supergreen” hydrogen creation could capture carbon from the air and de-acidify the oceans.


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