Carbon capture can’t reverse climate change, but it’s one part of the equation for reducing greenhouse gases. Earth’s atmosphere currently contains 415.26 parts per million (ppm) of carbon dioxide (CO2), the highest concentration in human history. Phys.org reports that, “The last time our air contained this much CO2 was more than three million years ago.”
The Carbon Problem
Excess amounts of CO2 are warming the planet’s atmosphere and oceans, melting ice caps, increasing acid in the oceans, and contributing to extreme weather events and rising sea levels. When CO2 concentrations were last this high, global sea levels were several meters higher and parts of Antarctica were covered in forest. While the evidence of climate change is staggering, environmental technology could provide some assistance.
The latest improvements in wind and solar technologies are making alternative energy cheap enough to compete with fossil fuels. Still, switching to clean energy takes time, and carbon capture and storage (CCS) could help us keep up with the fast pace of rising global temperatures. Plus, many industries may still rely on applications that require old-fashioned energy sources. Alternative energy sources are helping to decarbonize the power sector, but there are many industrial processes that will require CCS if they are ever going to decarbonize. Cement, iron and steel manufacturing, as well as petroleum refining, are all industries that produce CO2.
How Carbon Capture Can Help
According to MIT Technology Review, most energy researchers say that CCS will be necessary to address the growing dangers of climate change. “A number of studies have found that without this technology, it’s unlikely the world can prevent temperatures from rising more than 2˚C,” writes James Temple.
The obvious way to reduce greenhouse gas concentrations is to stop putting carbon into the air. But there are also ways to pull CO2 from the air.
Current Developments in Environmental Technology
With the latest technology, carbon emissions can be scrubbed from the air and stored underground. The main reason global temperatures are rising, according to Vox, is that we are removing too much carbon from the geosphere (below ground) and putting it into the biosphere (above ground). Take coal, for example. It starts as a solid underground, but then we mine for it, bring it above ground, and burn it for fuel. The burning process turns it into a gas that then disperses into the atmosphere, where it traps the sun’s heat.
Several facilities around the world are currently practicing CCS. They capture CO2 from the exhaust stream of a fossil-fuel power plant or heavy industrial process and bury it underground. It’s an expensive process, but the cost has dramatically reduced in recent years.
CCS is one strategy that can reduce the impact of CO2 on the climate while keeping fossil fuels as options. Existing power plants or industrial equipment could be retrofitted with carbon capture systems that would snatch carbon from the exhaust pipes before it is emitted into the atmosphere. Vox points out that CCS could help power plants become carbon neutral — but not carbon-negative. To get negative emissions, you have to take more carbon from the atmosphere than the ground.
How it Works
How do you pull carbon from the air? Chemicals. Popular Science breaks down the two capture processes:
- Pre-combustion: Carbon is separated from the fuel before it is burned. For coal, you turn it into a gas called syngas, then filter out the carbon. With natural gas, a chemical reaction separates carbon from the methane molecule before it is burned, leaving behind a clean-burning hydrogen gas.
- Post-combustion: Plants continue to burn fossil fuels, but they add an extra step that extracts the CO2 before it enters the atmosphere. This is accomplished using aqueous amines, which are liquid chemicals that bind to carbon. Later, the byproduct is burned to release CO2, which can then be pressurized and piped away to underground storage.
Where Does Carbon Go Now?
With all the talk about greenhouse gases, it’s easy to forget that carbon isn’t actually bad for the planet. The problem is that we’ve been moving it around too much. After carbon is captured from the air, it can be stored underground in porous rock formations. Other than saving the earth in the long term, there isn’t much incentive for industries to make an effort to put carbon into these underground saline reservoirs — but what if they could sell the carbon they capture?
There are several startups experimenting with new ways to take carbon out of the air. For example, the Allam cycle recycles CO2 from combustion into a high-pressure fluid that can run a turbine — in other words, taking a waste product that is bad for the Earth’s health and turning it into energy storage, according to Popular Science.
Carbon Engineering, a Canadian startup, has reduced the cost of capturing carbon and is aiming for commercialization in 2021. According to Vox, the cost to capture a ton of CO2 was approximately $600 in 2011, but it’s now somewhere between $94 to $232. This is still expensive, but at least Carbon Engineering proves that carbon capture is possible and the technology is improving with time. They plan to use solar-powered electrolysis to draw CO2 from the air. Then, they will use the carbon as an ingredient in low-carbon synthetic fuels.
We’ve put so much carbon into the air that simply reducing emissions might not be enough — but carbon capture could help pull carbon molecules out of the atmosphere and put them to good use, or at least put carbon back into the ground, where it came from.
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