Carbon capture and storage: research conclusions?

Carbon capture and storage (CCS) prevents CO2 from entering the atmosphere. Options include the amine process, blue hydrogen, novel combustion technologies and cutting edge sorbents and membranes. Total CCS costs range from $80-130/ton, while blue value chains seem to be accelerating rapidly in the US. This article summarizes the top conclusions from our carbon capture and storage research.

What is carbon capture and storage? CO2 is a greenhouse gas. But it is also an inevitable product of many energy-releasing reactions, from biology, to materials, to industrial energy, because of the high enthalpy of the C=O bond, at 1,072 kJ/mol. Carbon capture and storage technologies therefore aim to capture unavoidable CO2, purify it, transport it, and sequester it, to prevent it from contributing to climate change.

What are the costs of carbon capture and storage? 10-20% of all decarbonization in our roadmap to net zero will come from CCS, with the limit set by economic costs, ranging from $80-130/ton on today’s technologies, which is towards the upper end of what is affordable. Costs vary by CO2 concentration, by industry, by process unit, but will hopefully be deflated by emerging technologies.

Amines are the incumbent technology among 40MTpa of past carbon capture and storage projects, bubbling CO2-containing exhaust gases through an absorber column of lean amines, which react with CO2 to form rich amines. The CO2 can later be re-released and concentrated by steam-treating the amines in a regenerator. Base case costs are $40-50/ton to absorb the CO2 (model here). Energy costs range from 2.5-3.7GJ/ton. Energy penalties are 15-45% (note here). But a possible operational show-stopper is the emissions of amines and toxic degradation products (note here), with MEA breaking down at 1.75 kg/ton into a nasty soup (data here). Avoiding amine degradation is crucial and usually requires treatment of exhaust gases, to remove dusts, SO2, NOXs, a post-wash and limits on the ramp rates of power plants. This all adds costs.

Leading amines for CCS, which have been de-risked by use in multiple world-scale projects are MHI KS-1/KS-21 and Shell CANSOLV. We have also screened novel amines developed by Aker Carbon Capture (JustCatch), Advantage Energy (Entropy) and Carbon Clean. And alternatives to amines such as potassium carbonates. In our view, this space holds exciting potential, although decision-makers should consider the correct baselines, hidden costs and technology risks.

Blue hydrogen is an alternative to post-combustion CCS, directly converting the methane molecule (CH4) into relatively pure streams of H2, as an energy carrier or feedstock, and CO2 as a waste product for disposal. The two gases are separated via swing adsorption. The technology is mature, there are no issues with toxic emissions, and the world already produces 110MTpa of grey hydrogen, including 10MTpa in the US (data here), mostly via SMRs, emitting 9 tons of CO2 per ton of H2. 60% of the CO2 from an SMR is highly concentrated, and can readily be captured. An adapted design, ATR, can capture over 90% of the CO2 and is also technically mature (note here). Our economic model for blue hydrogen is here. An ATR technology leader is Topsoe.

Blue materials. The US seems to be leading in CCS, over 500MTpa of projects could proceed in the next decade (note here), and 45Q reforms under the Inflation Reduction Act are already kickstarting a boom in blue value chains, from blue ammonia, to blue steel, to blue chemicals. This exciting theme is gathering momentum at a fast pace and could even disrupt global gas balances and LNG exports (note here).

Novel combustion technologies are also maturing rapidly, which may facilitate CCS without amines. NET Power has developed a breakthrough power generation technology, combusting natural gas and pure oxygen in an atmosphere of pure CO2. Thus the combustion products are a pure mix of CO2 and H2O. The CO2 can easily be sequestered, yielding CO2 intensity of 0.04-0.08 kg/kWh, 98-99% below the current US power grid. Costs are 6-8c/kWh (note here, model here). We have also explored similar concepts ranging from chemical looping combustion to molten carbonate fuel cells and solid oxide fuel cells.

Transporting CO2 usually costs $4/ton/100km in a pipeline (model here). But CO2 is a strange gas to compress (note here). CO2 pipelines run above 100-bar, where CO2 becomes super-critical and behaves more like a liquid (e.g., it can be pumped). CO2 can also be liquefied 80% more easily than other gases, for a cost of $15/ton, merely by pressurizing it above 5.2-bar then chilling to -40C (model here). This opens up the possibility of trucking small-scale CO2 for c$17/ton per 100-miles (note here, model here). Similarly, seaborne transport of CO2 costs $8/ton/1,000-miles (model here), and this also opens up a possibility for the LNG industry to ship LNG out, CO2 back (note here). Ships could also capture their own CO2 with onboard CCS for $100/ton (note here).

CO2 disposal requires injecting CO2 into disposal wells at 60-120 bar of pressure. Our base case cost is $20/ton, but can vary from $5-50/ton (model here) and there can be risks (data here). CO2-EOR can re-coup costs of sequestration with an oil price around $50/bbl (note here, model here) and in the past we had hoped this would also drive a subsequent wave of low-carbon production via shale-EOR (note here).

CO2 utilization aims to make valuable use of the CO2 molecules rather than simply pumping them into the ground. Enhancing the concentration of CO2 in greenhouses can improve agricultural yields by c30% (note here). Some chemical pathways use CO2 directly, making methanol, formaldehyde and polyurethanes. The CO2 molecule can also be electrolysed to produce other feedstocks, but costs are c$800/ton (model here). CO2 utilization for curing cement industry is being explored by Solidia and CarbonCure. Other CO2 utilization companies are screened here. The challenge in all of these niches is scaling up to absorb GTpa-scale CO2 within MTpa-scale supply chains.

Direct air capture is a frontier for CCS that aims to absorb CO2, not from an exhaust gas with 4-40% concentration, but from the atmosphere, with 0.04% concentration. On the one hand, this is obviously more thermodynamically demanding, as dictated by the entropy of mixing, but on the other hand, the minimum theoretical energy for DAC is only 140kWh/ton, and the world has simply not invented a process yet that is more than 5-10% thermodynamically efficient. We have modeled solutions from Carbon Engineering at c$300/ton and from Climeworks at c$1,000/ton. Our DAC cost model is here.

Membranes. Next-generation membranes could separate 95% of the CO2 in a flue gas, into 95% pure permeate, for a cost of $20/ton and an energy penalty below 10%, which exceeds the best amines (note here). But today’s costs are higher, especially for pipeline grade CO2 at 99% purity (model here). A CCS membrane leader is MTR (screened here).

Metal organic frameworks are a novel class of materials with high porosity and exceptional tunability, which could become a CCS game-changer, but cannot yet be de-risked (note here). We have screened companies such as Svante in our work.

Cryogenics. The costs to separate the 20% oxygen fraction from air in a cryogenic air separation unit average $100/ton using 300kWh/ton of electricity (model here). If you have a concentrated CO2 stream (e.g., 10-40%) then cryogenics may be an option.

Some summary charts, workings and data-points from our carbon capture and storage research are aggregated in this data-file. All of our broader CCS research is summarized on our CCS category pages.

CarbonCure: concrete breakthrough?

CarbonCure technology review

CarbonCure injects CO2 into concrete during the mixing process, where it mineralizes to form CaCO3. The resultant product is up to 20% stronger and can most likely save 4-6% of the CO2 intensity of finished concrete.

Total CO2 abatement has recently been running at 60kTpa, across 300 customers, with a long-term aspiration to abate as much as 500MTpa potentially.

The technology scores OK on the TSE patent framework, although some question-marks are explored in the data-file, especially around the specific solutions discussed in the patents.

CO2 capture: a cost curve?

CO2 capture cost curve

This data-file summarizes the costs of capturing CO2 from different sources, so that it can be converted into materials, electro-fuels or sequestered.

Specifically, we have estimated the full-cycle costs (in $/ton), ultimate potential (in MTpa) and other technical considerations, linking to our other models and data-files.

The lowest-cost options are to access pure CO2 streams that are simply being vented at present, such as from the ethanol or LNG industries, but the ultimate running-room from this opportunity set is <200MTpa.

Blue hydrogen, steel and cement place next on the cost curve and could each have GTpa scale. Power stations place next, at $60-100/ton.

DAC is conceptually attractive, as the only carbon negative technology, but if all CO2 molecules in the atmosphere are fungible, it is not clear why you would pursue DAC until options lower down the cost curve had been exhausted.

CO2 electrolysis: the economics?

Economics of carbon monoxide production by CO2 electrolysis

Carbon monoxide is an important chemical input for metals, materials and fuels. Could it be produced by capturing CO2 from the atmosphere or using the amine process, then electrolysing the CO2 into CO and oxygen?

This data-file models the economics of CO2 electrolysis, including recent advances from leading industrial gas companies, and by analogy to hydrogen electrolysis.

10% IRRs can be achieved at $800/ton carbon monoxide pricing, which can be competitive with conventional syngas production, and far more economic than small-scale distribution of CO containers.

The data-file contains input assumptions, detailed notes from half-a-dozen recent technical papers, and short summary of different companies’ initiatives, including Haldor Topsoe, Siemens, Covestro, Methanex and Carbon Recycling.

Tree database: forests to offset CO2?

CO2 uptake rates in forests by tree type

Nature-based solutions are among the most effective ways to abate CO2. Forest offsets will cost $2-50/ton, decarboning liquid fuels for <$0.5/gallon and natural gas for <$1/mcf (chart below).

CO2 uptake rates in forests by tree type

The data-file tabulates hundreds of data-points from technical papers and industry reports on different tree and grass types. It covers their growing conditions, survival rates, lifespans, rates of CO2 absorption (per tree and per acre) and their water requirements (examples below).

CO2 uptake rates in forests by tree type

Carbon offsets: costs and leading companies?

Carbon Offset Costs

This data-file tabulates the costs of carbon offsets being offered to consumers and commercial customers by c30 companies. Prices are surprisingly low, ranging from $4-40/ton of CO2.

Which projects are most economical? Costs are lowest at forestry projects, particularly at companies where you pay “per tree” rather than “per ton” of CO2. They are also lower at non-profits (which also means contributions are tax-deductible). Finally, they are lowest at companies undertaking projects directly, rather than as “middlemen” (charts below).

Are they CO2 offsets real? The also file contains detailed notes on each company, to assess their credentials. Moreover, it tabulates 1,600 carbon offset projects which are assured by agencies such as the ‘Verified Carbon Standard’, Gold Standard and Green-E, for a broader perspective.

Offset your own CO2? We have used the data-file to select and allocate carbon offsetting dollars to Eden Reforestation, One Tree Planted, The Gold Standard and Sea Trees. We are happy to discuss CO2 offsetting with TSE clients and those using the data-file.

Ventures for an Energy Transition?

Oil Major Venture Investments

This database tabulates almost 300 venture investments made by 9 of the leading Oil Majors, as the energy industry advances and transitions.

The largest portion of activity is now aimed at incubating New Energy technologies (c50% of the investments), as might be expected. Conversely, when we first created the data-file, in early-2019, the lion’s share of historical investments were in upstream technologies (c40% of the total). The investments are also highly digital (c40% of the total).

Four Oil Majors are incubating capabilities in new energies, as the energy system evolves. We are impressed by the opportunities they have accessed. Venturing is likely the right model to create most value in this fast-evolving space.

The full database shows which topic areas are most actively targeted by the Majors’ venturing, broken down across 25 sub-categories, including by company. We also chart which companies have gained stakes in the most interesting start-ups.

Alternative truck fuels: how economic?

economics of trucking fuels

This data-file compares different trucking fuels — diesel, CNG, LNG, LPG and Hydrogen — across 35 variables. Most important are the economics, which are fully modelled, in the 2020s in the US, in the 2020s in Europe and incorporating deflation in the 2040s.

Hydrogen still screens as an expensive alternative. We estimate full cycle freight costs will be c30% higher for hydrogen vehicles than diesels in Europe, and as much as 2x higher in the US. The data-file contains a breakdown of hydrogen truck concepts and their operating parameters.

Natural Gas can be close to competitive. On an energy-equivalent basis, $3/mcf gas is 4x more economical than $3/gal diesel. However, the advantages are offset by higher vehicle costs, operational costs and logistical costs. Mild environmental positives of gas are also offset by mild operational challenges.

Restoring soil carbon: the economics?

economics of restoring soil carbon

This model illustrates the economics for conservation agriculture, restoring soil carbon to improve agricultural yields, while also sequestering 5-30T of CO2 per acre per year.

Agricultural economics are transformed from marginal to material, as yields improve 10-20% and costs fall 36-73%, including the potential elimination of fertilizer application.

Please download the model to stress-test input assumptions into corn prices, fertilizer prices, diesel prices and CO2 prices; as well as yields and soil carbon uptake rates.

CO2 disposal in geologic formations: the economics?

costs of CO2 sequestration

Costs of CO2 sequestration — i.e., disposing of the CO2 in geological formations — is extremely variable and project-dependent, ranging from $5-50/ton.

Our base case is c$20/ton. This is the disposal price needed to earn a 10% post-tax IRR, transporting, injecting and monitoring CO2 in the sub-surface.

This model captures the economics and costs of CO2 sequestration in geological formations, as a function of a dozen input variables: such as CO2 prices, costs, transportation distances and reservoir properties.

Our capex and opex estimates are broken down, line-by-line across c30 different line-items, using granular technical disclosures from the EPA’s GEOCAT database.

Offshore Sequestration Costs. Our modelled costs are also compared with detailed estimates for offshore disposal beneath the UK North Sea, based on recent technical papers.

Regulation is also challenging. For example, some projects will be required to monitor the injection site for over 50-years after injection has ceased, to ensure CO2 does not leak back out again.

Please download the data-file to stress tests the economics. CO2 sequestration is one piece of a three-piece chain required for CCS, alongside CO2 capture (e.g., using the amine process) and CO2 transportation in a CO2 pipeline or with CO2 trucks. Our recent research has also sought to quantify the upside in CCS.

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