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Response: Negative emissions technology – carbon capture and storage

CO2 converted to sold rock – image: CarbFix

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Negative emissions technology – carbon capture & storage…or not


Home > Climate wiki > Response > Negative emissions technology


  • The world’s plan by 2050: remove 8 billion tons of CO2 every single year and put it back underground (negative emissions).
  • This calculation is based only on what humans are releasing. It doesn’t include the staggering volume of greenhouse gases now being released by collapsing ecosystems.
  • The IPCC pathways assumed that negative emissions technology would be invented ‘spontaneously’ and rolled out across the planet. Currently, most tech that draws carbon from the atmosphere sells it as fuel, returning the CO2 straight back into the atmosphere.
  • Some tech injects captured CO2 into depleted oil wells, to squeeze out the last few drops of oil, to keep us addicted to fossil fuels.
  • DACC is genuinely negative emissions technology, however the carbon cost of implementing it at scale vastly exceeds the carbon it sequesters by orders of magnitude. Most others are misleading at best, and at worst, dangerous greenwashing.
  • The IPCC favours BECC: planting monoculture pine plantations and taking away a large chunk of land needed to grow food. This process also burns trees and returns the carbon to the atmosphere.
  • In spite of calculations under the current emissions trading scheme (ETS), almost all natural ecosystems including soils and the ocean permanently remove carbon from the atmosphere at no cost while also providing ecosystem services that we literally cannot live without.
  • We recommend watching the videos as they expose the false claims and loopholes many industries are legally exploiting.
  • See also the latest (January 2023) summary of all CO2 technologies and processes.

DACC: Direct Air Carbon Capture with Sequestration (permanent storage as rock underground)

Captures and stores carbon (negative emissions) by extracting CO2 from the atmosphere using renewable energy and converting it into solid rock (calcium carbonate) deep underground in basaltic rock within 2 years. Carbfix (Iceland, powered by geothermal energy which, unbeknown to most people, emits CO2 )and Climeworks are the only joint companies currently doing this (Fig. 1 and Videos 1 and 2).

Four key hurdles:

1. The site in Iceland is on an active volcanic complex; sequestration is only ‘permanent’ until the next eruption. If the site is regarded as a proof-of-concept only, then:

2. Currently, the full carbon cost of construction and deployment at a scale vastly exceeds the amount of carbon being sequestered.

“The energy requirements for a net removal of ~ 3.3 gigatons of carbon equivalents by amine DAC “would amount to a global energy requirement of  29% of total global energy use in 2013 (540 EJ year−1)”, equal to nearly the total amount of electricity generated in the U.S. in 2017. Yet, even these amounts omit some downstream components of the DAC life cycle process, such as the energy requirements for transportation or sequestration of the captured CO2 and energy requirements for manufacturing sorbent at scale.” – Alice Friedemann |Quote from Joppa et al 2021

3. If CO2 can be stored underground near factories that use renewal energy but produce large amounts of CO2, then the cost of will become much more appealing. However, this requires mining suitable rock types. New Zealand has suitable rock formations, surrounded by naive ecosystems.

4. While Climeworks’ scaled up operations in 2021 it can only draw down and store 0.000004Gt of CO2/year. To scale up to 3.9Gt/year, which is the IPCC’s plan, would require building and deploying 9.5 million additional fully operating plants of the same size. To scale up to 24Gt/year from 2050 onward would require 58.5 million additional fully operational plants of the same size.

Their scaled up ‘Mammoth’ project announced in June 2022, is yet to be built, and even if it can eventually draw down 10x more than the existing Orca project, that’s still only a fraction of current emissions.

In March 2021 Northern Lights partnered with Climeworks to develop the same processes to store CO2 off the coast of Norway. Give the urgency of the climate problem, the company is developing the world’s first open-source CO2 transport and storage infrastructure to enable and encourage innovation and technology development in a fully transparent manner.

“The key is to identify the right place to inject and contain the CO2, which is trapped in microscopic rock pores by the same process that trapped oil and gas and natural CO2 for millions of years. Geologists look for a permeable rock formation that is stable and deep enough to ensure the CO2 is a dense fluid rather than a gas.

Close monitoring, using seismic data, is used to refine theoretical models and check that the CO2 is moving within the rock space as expected (this is known as “plume migration”). In Snøhvit, for example, plume monitoring shows some of the CO2 trapped in rock spaces due to capillary forces, some dissolved in brine and some mineralised into rock.” – Northern Lights

Fig. 1: Carbfix stores carbon permanently underground. The process involves injecting carbonated water several thousand metres underground in basaltic rock formations, where it rapidly (less than 2 years) mineralises into solid rock (see image at the top of this page).
Video 1
Video 2: This video was filmed in 2016. Climeworks and Carbfix went from the laboratory in 2014, to complete proof of concept by 2016, and is now expanding.
If the (full life-cycle) carbon emissions cost of DACs drops below the amount of carbon stored, then the technology becomes genuinely negative.

DAC: Direct Air Capture: recycles CO2 back into the atmosphere, ie, not ‘negative’

Removes carbon from the air using an exceptionally costly process, but instead of storing it, recycles it into more fuel, which means it goes straight back up into the atmosphere. For example, Carbon Engineering in Squamish, Canada, which calls itself ‘air-to-fuel’ technology, is backed by one of the dirtiest types of fossil fuel developers on the planet: the oil sands in Alberta. This is not negative emissions technology. It’s reselling used fossils fuels, claiming them to be climate-friendly or even more disingenuously, ‘carbon-free’:

“Imagine driving up to your local gas station and being able to choose between regular, premium, or carbon-free gasoline.”        – National Geographic

While industries such as airlines and shipping are using DAC because there is yet no viable alternative to fossils fuels, some heavy fossil fuel industries use it as an excuse to continue business as usual, while claiming to be helping the planet (Video 3).

Video 3: 13-min. video explains DACS, which is definitely not carbon negative technology. It’s worth listening until the end, even though it verges into the politics of climate change, as it points out the truth behind the investors in DAC.

CCS: Carbon Capture and Storage underground (not the same as DACCS)

Fossil fuels are taken from the ground, burned by factories and power generating plans, and the CO2 they emit is captured before it goes into the atmosphere. They then have three options:

  1. Inject it onto oil wells to force out the last few drops of oil. This is called ‘Enhanced Oil Recovery’. Companies in the US enjoy massive tax breaks for ‘sequestering’ carbon this way. It’s the worst kind of greenwashing as it perpetuates oil addiction
  2. Inject the CO2 into sedimentary rock formations and dry aquifers. Given their past assurances about the safety of their operations, this raises concerns about the potential for CO2 leaking out over the coming decades. Potential leakage notwithstanding, it still means taking more fossil fuels out of the ground and burning them, continuing fossil fuel addiction.. Companies that claim to capture 100% of their CO2 doesn’t make them ‘carbon neutral’ unless every aspect of their business offsets 100% of all carbon costs for the full life-cycle of every aspect of their business including the cost of the materials used to build structures, make products, transport them, capture all of those emissions as well, and guarantee storing the captured CO2 gas underground indefinitely.
  3. As the price of carbon increases, market forces should incentivise heavy fossil fuel users to use processes that  DACC use, ie store the captured CO2 in suitable rock formations.

BECCS: Bioenergy with Carbon Capture and Storage (growing and burning forests)

“We found that in a majority of the areas where forests will be replaced more carbon is stored by keeping the forests.” – Smolter and Ernsting

BECCs is favoured by the IPCC in its modelling: plant lots of fast growing plants such as radiata pine, cut them down, burn them (‘bioenergy’) capture the CO2, inject the gas underground and hope it stays there or sell it for Enhanced Oil Recovery, burn that newly recovered oil, adding more CO2 into the atmosphere, grow more radiata pine…repeat.

Despite the fact that Enhanced Oil Recovery leads to the recovery and burning of potentially vast quantities of fossil fuels which would otherwise have remained under the ground, use of CO2 for this purpose is classed as a form of CCS, a claim accepted even by the Intergovernmental Panel on Climate Change. ” – Smolter and Ernsting

For BECCS to work, it would mean replacing much of the existing native forest on the planet with fast growing trees, destroying irreplaceable, life-supporting ecosystem services and releasing carbon locked up in those forests and their soils. Additionally, by 2100 BECCs would also need to use around 25-46% of the land currently used to feed people (Video 4). While New Zealand may find ways to avoid some of these problems, the same cannot be said for developing nations keen to cash in other nations’ (including New Zealand’s) need to purchase carbon offsets in order to meet obligations under the Paris Agreement. To understand how flawed BECCs is, see this timeline.

Bioenergy with carbon capture and storage is expected to capture, on average, around 130 billion tonnes of carbon via planting crops for biofuel that are then burnt in power stations…. It is expected that an additional area of one or two times the size of India is needed for bioenergy crops by 2050.” –  Dr Anna Harper, University of Exeter.

Video 4: BECCS: the not-so good, the bad, and the really really bad.

My colleagues and I find that expansion of bioenergy in order to meet the 1.5C limit could cause net losses in carbon from the land surface. Instead, we find that protecting and expanding forests could be more effective options for meeting the Paris Agreement. ” – Dr Anna Harper, University of Exeter

Bioenergy from burning slash with CO2 pumped into greenhouses

Using heat by burning the slash from radiata pine and other waste plants, then pump the emitted CO2 into  greenhouses to increase plant growth does seem like a good idea. However, while plants exposed to higher levels of CO2 may grow faster, their nutritional values are declining (Video 5) and structurally weaker. This may limit the use of this process to growing short-lived non-edible products like flowers.

Hot Lime Labs in New Zealand uses this process. Climeworks also does this in Switzerland, although they capture the CO2 from DAC, not from burning biomass. Further research is strongly recommended to assess the nutritional value of food grown using this method.

Video 5: What’s causing our food to become less nutritious?

Carbon captured and stored in concrete

  • For every metric tonne of cement produced, one metric tonne of CO2 goes up into the atmosphere
  • The world uses 4 billion tonnes of concrete every year
  • Additionally, fossil fuels like powdered coal are requited to to melt limestone, resulting in a more CO2 emissions
  • The cement industry accounts for 8% of total greenhouse gas emissions

Several companies are now finding ways to permanently store CO2 in concrete. Not all are ‘carbon-negative’ as claimed, however the processes are innovative and look extremely promising to reduce carbon emissions. See their websites for more information:

  • Carbon Cure uses CO2 from industrial emitters
  • Carbicrete uses mineral waste and CO2 as raw materials
  • Blue Planet uses CO2 as raw material for making carbonate rocks
  • Solidia produces cement at lower temperature, ie reduces emission
Video 6: Carbon capture in concrete

Use algae to grow your own cement

Biomason uses a natural non-modified non-pathogenic bacteria to grow biocement® building material without heat, using a process similar to hydroponics. The species used is commonly found in natural environments across the world.

It takes around 72 hours for Biomason’s tiles to reach full cure strength (traditional concrete can take up to 28 days to cure) and the product is 3 x stronger than concrete (Video 7).

In marine environments, self-sustaining natural marine microorganisms that source nutrients from seawater, are used to propagate calcium carbonate precipitation (similar to how beach rock is formed, but over much short time frames). The result is the sustained structural integrity of products with self-healing abilities. This process can be used to quickly build breakwaters and other ‘hard’ coastal/marine structures.

See: ‘Tiny algae could help fix concrete’s dirty little climate secret – 4 innovative ways to clean up this notoriously hard to decarbonize industry.’ – The Conversation, Sept. 2022 (Video 8)

Video 7: Growing bricks using hydroponics
Video 8: Laying the foundation for the future of carbon-zero buildings

More information

  • The safest way to store CO2 underground is in places where the CO2 is mineralized, that is, it becomes a rock. This is the process used by Carbfix in Iceland for DACC. Considerable research and experimentation is currently underway to find locations and/or other types of minerals that can be used to enhance this process.
    If places to store CO2 underground permanently can be found close to factories producing large amounts of CO2, the cost of storing carbon safely in rock formations will become more appealing.
    As with all things, there are likely to be trade-offs. For example, one kind of rock called olivine may help with this mineralisation process:

    Our preliminary investigations have shown Mg can also be extracted from basalt; however, we will primarily focus our discussion on two enriched and accessible olivine deposits: the Semail ophiolite (Oman) and the Red Hills Ultramafic Complex (New Zealand) which conservatively contain 1.4 × 105 and 871 billion tonnes of olivine, respectively.              –  Scott et al (2021)

    But Maungakura Red Hills near St Arnaud is part of the Mt Richmond Forest Reserve; it’s surrounded by native ecosystems that already store massive quantities of carbon dioxide (images). The whitish area in the centre of the second image is an ephemeral riverbed, not a road.

    How much carbon-absorbing and life-supporting ecosystem services provided by biodiversity are we prepared to destroy through carbon-emitting mining and processing activities?

    (Images: Cody Whitelaw, 2019)