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Power generation & industry is likely to continue to need fossil/bio-fuels for decades. HCCAS converts the CO2 to O2 AND makes food/biofuel.



Much infrastructure is carbon fuel based, and much is essential and highly distributed so unlikely to be fully substituted  for decades. That means ongoing CO2.

Conventional CCS buries CO2 - expensive, zero payback, and a liability for our kids. Most emitters lack suitable geology so incur high cost shipping CO2 to CCS.

Hydroponic Carbon Capture At Source - HCCAS - uses CO2-rich flue gas on-site to grow plants hydroponically in a soilless environment for food or biomass. More detail on my site.

HCCAS scrubs nasties from flue gas, recovers its heat and H2O to supply the hydroponic units (HUs), then feeds clean CO2-rich gas to the HUs where controlled environment accelerates plant growth.


Low-tech + low-cost. Ambient pressure, ambient temperature, simple (so workable regardless of local technical ability).

Low-risk combining established technologies.

Failsafe; worst-case failure returns emissions to pre-HCCAS level. No pollution, explosion, radiation or other bad stuff.

Cheap to run. Input heat and water is recovered from flue gas. Most water is transpired and can be recycled without treatment. Even better, HCCAS EARNS income by producing marketable green produce.

REALLY efficient LOSSLESS agriculture. Growth is accelerated 50% by this LED lighting and 30-40% at higher CO2 levels so may outperform field farming by 80-90%. Should also be immune to pests and weather so this may hit >100%, AND is largely immune to climate change. Adding ADU scrubbing should also allow growing of healthy plants in polluted air.

Farmland saving. Greenery produced saves on valuable farmland use.

Scalable and portable - lends itself to ISO-container format pluggable module design.

Retrofit-friendly to anything. Can work on ANY large carbon emitter of ANY age or scale. Bespoke/modular option means great flexibility.

CCS compatible - can work with downstream CCS;  post-HCCAS reduced CO2 burden makes CCS easier/cheaper and fills CCS facilities more slowly.

Cut CO2, make O2, feed people. Schematic:

Schematic of hydroponic carbon capture at source

Category of the action

Reducing emissions from electric power sector.

What actions do you propose?

This section considers the organizational and practical steps to move the project forward. Funding is only briefly touched upon as there are too many options to discuss in detail.

3 project phases are considered; funding & organisational outline; initial research; and development phase. Pilot and subsequent roll-out are not discussed in any detail, being for now too distant.

The “research components” (RCs) – key activities in each area – are identified. 9 RCs emerge.


  1. Agree funding outline for initial research.
  2. Set up a sponsoring university-based project for research to prove concepts and pilot baseline technologies.
  3. Assuming successful, establish suitable funding vehicle to obtain wider income. The nature of the project suggests this would be a combination of government and corporate funding.
  4. Build appropriate expert forum - chemical engineers, hydroponicists (is that a word?), systems guys... led by suitable expertise (selected by the forum - must of course also be acceptable to the funding providers)
  5. Move to development stage, recruiting additional resources as required. As details are finalized and designs firm-up, seek further funding perhaps through additional funding vehicles.
  6. Pilot in one or two real-world projects to obtain public buy-in and debug processes and technology.
  7. Roll-out. This will entail large-scale construction, both for emitter sites for bespoke builds and of factories to produce the HU modules for modular builds.



Since rather than being entirely new HCCAS combines existing technologies (see for example this Japanese hydroponic farm and this LED system), by partnering academic and real-world expertise research timescale should be short and move to development rapid.

Initially we must identify and prove key feasibility issues. How much CO2 uptake is achievable, by what crops and in what effective volume/area?

It must be stressed that in the absence at this preliminary stage of any design optimization, or any work on optimal crop selection,  these initial results will probably be far short of what’s possible.

It is suggested this initial research be at a university, ideally one with good expertise in both Chemical Engineering and (plant) Biology and where hydroponics research is already underway.

Concept feasibility research in the form of small-scale experimentation should be able to establish CO2 uptake, and crop yield, of a selection of representative test crops fed with air-diluted cooled boiler flue gas. Note that to be remotely representative of HCCAS potential, this research MUST embody the core technologies of air dilution (see Component C of Development, below) to optimize CO2 levels for the 30-40% yield boost correct CO2 levels provide, AND this LED lighting which should improve output by a further 50%.

Since at this stage the crop is not for food, gas cleanliness should not be an issue (unless constituents that scrubbing would remove actually reduce CO2 uptake – needs to be considered).

Appropriate crops, displaying high CO2 uptake AND suitable for food or biomass applications should be selected for the experiment - botanical/plant biology advice is essential. This comprises the first research component.

This component must generate sufficient data to allow a decision on progress to be taken based on 3 primary criteria:

  • CO2 reduction benefits
  • crop economics (considered both as food crop and biomass)
  • required space/volume (for HCCAS construction economics)

Assuming this to be successful the project can move to the development phase.


Each component of the process schematic in the Summary is considered in turn.

Component A: Scrubbers

Where the CO2-rich gas and recovered water is to be used in food production it is essential that undesirable components are removed. Scrubber technology is well established; this component will leverage that to identify and prove the optimal scrubber design for HUs.

Scrubber research will also address recovery from scrubber effluent of the removed elements, which will obviously need to be as environmentally friendly as possible.

For schematic purposes heat recovery is shown as separate from the scrubbers. In reality all heat transferred or generated in scrubbing would also be recovered.

Component B: Flue gas heat & water recovery

Heat recovery (HR) from gas is well established and various systems exist; see for example this article from Asia. Selection and sizing for a given emitter should be straightforward.

Water vapor naturally condenses out in the process; most entrained vapor should be recoverable,

However, two questions arise for HR application in a hydroponics environment. First is the best form of heating for hydroponic units (HUs); as this will directly impact design and build of HUs and HR, this research must be among the earliest in the program.

The second is where HR is best located; since HUs may be some distance from the gas source, we need to establish whether it is thermodynamically more efficient to transport hot flue gas to an HR unit at the HUs, or to locate HR as close as possible to the flue and transport the heated HR medium to HUs.

Component C: Air dilution

Crops have differing tolerances for CO2. The air dilution unit (ADU) mixes ambient air with the cooled clean flue gas to dilute CO2 levels to the optimum for the plants used.

Note that the schematic is illustrative only; in practice, CO2 levels will fall as CO2 is absorbed into the crops as it passes through the HU. Accordingly optimal CO2 absorption will most likely be obtained by feeding additional CO2-rich gas incrementally to gas streams partway through the HU chain in order to maintain CO2 levels at optimal concentrations throughout the process, in turn maximizing plant CO2 uptake (and so crop growth/yield). Mixed crops may also require differing CO2 levels. ADU is thus likely to be a distributed element, rather than single unit as shown.

Component D: Hydroponic unit (HU)

To consider research required for the HU, it is first necessary to review the HU concept.

As mentioned above, HCCAS lends itself to an ISO-container format pluggable module design. It equally lends itself to a bespoke build, configured around available space/height/footprint on a larger carbon emitter site.

A pluggable ISO-container-dimensioned module design allows for a globally-standardized format, permitting cheap mass-production with users supported by a universal maintenance/spares infrastructure. ISO container dimensions also permit easy shipping and handling using universally-available handling equipment; the format also allows for very dense storage and installation.

All services (water, nutrient feed, power) would be pre-installed on the module, allowing multiple units to be plugged together (including vertically – see below for harvesting considerations) permitting an installation of any size to be quickly deployed and commissioned.

Whether however deployment at a location is bespoke build, or uses ISO-container format units, the design must address the same parameters; planting, gas flows, nutrient and water provision, lighting, and crop harvesting. These drive the key research areas.

First is crop selection. Some crops will be more available and will grow better than others in different locations, and there is likely also to be an element of what the local market will want (not all of which may be compatible with HCCAS). Offsetting this is the need to absorb CO2; a less efficiently-absorbing crop can still be used, but at the cost of needing more HU capacity to yield the same CO2 absorption. Accordingly, considerable work will be required to identify the optimal crops (food/biomass/mixed) for a location.

Current research such as this or this article from on common conventional species indicate that elevated CO2 does increase growth, so combined with this LED option we can expect considerably greater productivity from HCCAS than from "normal environment" farming. However, it is likely that other species may be more suitable for a biofuel application; plants similar to some prehistoric species which flourished when CO2 levels were much higher may be a better bet.

It should be noted that RC7 is NOT on the critical path. ALL plants absorb CO2 and HCCAS can be initially implemented to grow most crop(s) desired (subject to space/weight constraints), these being later substituted by more optimal ones as research identifies these.

Second is gas flow. Higher gas flow will have greater turbulence which may improve CO2 take-up; however not every plant is amenable to windy conditions. Designing/controlling the gas path and flowrate to optimise CO2 take-up, especially in a changing and highly-irregular path such as growing plants will create, will be a challenge. The design will probably also need to take into account incremental addition of fresh CO2-laden gas, see RC6.

The third is delivery of water, nutrients and light. These are already well established in hydroponics, and aren’t at this stage discussed further here. See however RC8 below.

The fourth, lighting, is the proposed LED lighting supplemented by ambient light where possible.

The last is crop harvesting. Key issues will be mass, access (including height considerations in multi-level HCCAS), crop robustness (to minimise losses in harvesting process), and working environment (elevated CO2 levels make for an unsuitable working environment for humans). However, the irregular nature of crops together with handling issues probably does not lend itself to robotic harvest. Robotics are in any case unsuitable for many parts of the world; it must be remembered that many HCCAS installations will be well away from large cities and technological levels may not be up to working with a robotic solution.

Accordingly, taking into account these constraints a “cassette” system is envisaged, which addresses all these aspects effectively. The cassette is configured to slot-in to the ISO container format, but would work equally well in a bespoke build (a modified format could be used if preferred, although this would compromise the standardization benefits).

The cassette is pre-fitted with supporting structure, water/nutrient pipework, and LED lighting which plugs-in to a permanent “socket” array when the cassette is “fitted”.

The cassette will be pre-planted with crop seed/seedlings – outside the HU, in a human-friendly environment – then installed into the HU. When the crop was ready to be harvested the cassette would be removed from the HU, and the crop harvested; the cassette would then be re-planted and so on.

A cassette system such as this offers many advantages:

- it allows for any mix of human labour and automation to handle the cassettes, so is suitable for both high-tech and more primitive populations/locations

- it would permit a high-density hydroponics installation to be configured similarly to a multi-level high-racking warehouse, with cassettes being loaded/unloaded using standard or little-modified warehouse equipment

- by pre-planting cassettes, non-productive time harvesting and changing-over is greatly reduced so CO2 uptake maximised

 -a standardised cassette system offers the same standardisation benefits as does the ISO-container format HU module, as discussed above

- as above, the problem of humans working in a high-CO2 environment is removed


In parallel with cassette design must be


This appears to address all the currently-apparent considerations of feasibility. Assuming the HCCAS concept itself to be viable, there appears to be a fairly clear roadmap of development and rollout which should be attainable in the timescales below.

Who will take these actions?

Initially I'm looking for a sponsor or academic-industrial partnership to pick up proof of concept.

Once the potential is demonstrated I would envisage development of a funding vehicle (see previous section) for development, this vehicle then growing and being supplemented to move development forward.

Once development is done and HCCAS is real I'd hope that industry, NGOs and governments would pick up globally and run with the idea on a global scale. The economics and social acceptability should be WAY better than current "down-a-hole-in-the-ground" CCS and I think momentum will simply take over.

That's the plan...

Where will these actions be taken?

Can be in any location. Ideally I'd like to see a global project with contributing experts from everywhere. The key word in "global warming" is global - it's everyone's problem and our leaders need to act together.

It's essential we recognize that local factors can affect implementation. It's highly unlikely we can agree on one single model in detail that will work everywhere - ideal crops for example are unlikely to be the same in Russia as in Brazil - but the concept should be very portable and can hopefully be delivered in a standardized format to allow the economic and practical benefits of standardization to be leveraged.

Nonetheless, detailed implementation at local level will inevitably differ and the project must not get bogged down - like so many have before - in endless discussion of a "one size fits all" model. That will fail, and will consume valuable time we may not have.

How much will emissions be reduced or sequestered vs. business as usual levels?

Depends on the installation, which will depend on funding, land,  local environment etc.

I would think reduction in emitted CO2 of 30-50% possible. Better reduction may require combining hydroponics and algae (which adds complexity so may be unachievable in lower-tech areas).

A study by The University of Applied Sciences in Dresden using Hedera helix 'Woerner' states, "nearly 2.4 kg of carbon dioxide is bound and 1.7 kg of oxygen released per m2 of hedge area per year." And "One m2 of the element area ...requires 1012 kg of water per year... of which only 0.76% remains in the plant." - the rest is transpired so easily recoverable. The capability of plants to capture CO2 is proven; this improves by 30-40% in higher CO2 concentrations. Much better performance should be attainable with the right crop.

Infrastructure required WILL be large, handling 100s or 1000s of tonnes of plants per day. However, this is a cash crop so pays-back, and frees-up equivalent farmland as well as cutting CO2.

What are other key benefits?

  1. Reduced CO2 emissions
  2. Increased O2 - fresher healthier air
  3. H2O savings - heat recovery condenses vapor for re-use AND prevents H2O going to atmosphere
  4. Highly efficient agriculture system largely immune to effects of climate change
  5. Savings in farmland not needed to grow the same product
  6. Savings in transportation costs and emissions that would result from shipping substituted biomass
  7. Reduced residual CO2 so lower CCS costs if CCS still required
  8. Extended life of CCS facilities as they'll fill more slowly
  9. Employment opportunities in a clean, green environment
  10. Cheaper more plentiful food, particularly in less fertile areas where a hydroponic solution may massively improve livelihoods.
  11. Potential resource conflict reduction in areas where food is short.
  12. It's big & visible & VERY green. If as I expect it can also reduce food costs it will also be popular. So should encourage popular belief in the benefits of environmental projects which will pave the way for other projects.

What are the proposal’s costs?

I don't have the information I need to cost up effectively, sadly. However, I'd reckon ball-park costs for a custom installation for a large-scale emitter may be similar to installing CCS (and considerably less if we take into account the long-term operating costs of CCS).

While detailed costs of HCCAS are unavailable, I believe there is sufficient information to reasonably compare HCCAS with conventional CCS.

As far as I can establish CCS has high build cost, continued high ongoing costs, and offers zero payback. It needs expensive transport of CO2 from emitter to CCS facility, and ultimately yields a long-term risk to our children should containment fail.

Initial build cost of HCCAS depends on how much CO2 we wish to capture; the concept is fully-scalable with a fairly small fixed-cost element (collector, scrubber, heat recovery, ADU) allowing facility to start small and grow.

Operating cost of HCCAS should be minimal; obviously more green produce grown produces higher payback, and input costs (see above) should be low so higher output should quickly recoup build costs.

The proposed HCCAS modular approach transforms the economics for smaller emitters, eliminating the need for costly bespoke infrastructure and allowing HCCAS to be deployed much faster and more cheaply than CCS, particularly in more remote locations, while also bringing vastly greater local benefit.

As well as CO2 reduction, delivery globally of a highly efficient agriculture system largely immune to changing climate and deployable anywhere must in itself be of considerable value.

One more point to make is that to feed growing populations we'll need more production. To achieve that will almost certainly require hydroponic solutions. If you're going to build hydroponics anyway, why not do so where CO2 is much more concentrated - i.e. carbon emitter flues - than it is in the general atmosphere, which should dramatically increase output?

Time line

This is established tech that's simply being brought together, so we should be looking at incremental development only.


6-12 months to prove feasibility.

3-4 years to develop.

7-10 years to pilot and debug.

5 years to build a significant installation. HOWEVER, since the tech is all the same there's no reason multiple plants can't be HCCASd simultaneously; there's no need to switch off the plant during the build, and diverted flue gas volume can be gradually increased as build progresses. HCCAS could be operational within a few months of breaking ground, accepting more and more CO2 as the build extends.

The modular systems would be developed in parallel so should be deployable I would think on a 10-15 year schedule. Deployment rate is really down to how fast we want to build the modules.

Looking longer-term fossil fuel sources will deplete; however the technology will work perfectly well in a biomass-fuelled environment so can continue in service for the foreseeable future.

Related proposals

My own in the Industry sector contest, no others that I'm aware of.


Based on an internet search and (web-based) patent search, the concept appears to be novel. The points made and benefits are I think largely self-explanatory.

I'd like to thank the University of Dresden for providing core numbers on the efficiency of carbon fixing by plant growth; here is the link to their study.