A new cleantech taxonomy

Classic definitions of cleantech, and the industries under its umbrella, have gotten long in the tooth. The sector has changed, and taxonomies haven't kept up.

Why is a clean technology taxonomy important? As a list of nested categories, it shows where a clean technology “fits”. It helps vendors understand their competitive sets. It defines and helps investors understand the breadth of the sector and its sub-categories, and helps research and data organizations report consistently.

So if it's so important, why haven’t leading cleantech taxonomies kept pace with the sector's evolution? Because it's hard. Especially for cleantech data companies like Dow Jones, Bloomberg New Energy Finance, GTM Research, PwC/NVCA MoneyTree, or Cleantech Group. Any edit could mean having to re-tag years of data in difficult-to-change back end systems. And, truth be told, there are usually more profitable things for a data company to do than pay people to sit around and think about what cleantech is, what it’s not and how the industries it spans should be organized.

Ah, but it's a different story for a fledgling new cleantech research and advisory shop. At our firm, the taxonomy of cleantech is something many of us have been itching to dig into for years. We've seen the limitations in today's taxonomies. And so, the last few months, I and the high profile consulting, analyst and writer colleagues I've been lucky to work with in the cleantech research and consulting team at Kachan & Co. have been quietly working on our own take, which I now get to share with you for your feedback.

Cleantech definition taxonomy (c) 2010 Kachan & Co.

As a new firm, it was an important exercise for us:

  • It gave us a brand new framework for tagging and scheduling current and future research and analysis
  • We were able to rethink what many organizations have been holding up as 11 hallowed categories of cleantech (we think there are only 8 that deserve to be high-level categories. See our detailed classification, below.)
  • We were able to use our collective dozens of years in this sector to make some logical changes that we’d all been wanting to make, e.g. categorizing smart grid as a subset initiative within the larger phenomenon of energy efficiency. Or collecting green building-related materials under a category we call clean industry, recognizing that these materials are used more widely than just in structures for green building.
  • We adopted terms the market has settled on, and did away with outdated terminology
  • We chose not to categorize projects financed. Therefore wind, solar, even aquaculture farms don’t appear here as categories. We intentionally framed this as a taxonomy of technology and business model innovation.
  • It required discipline to remember the exercise was a classification for technologies, i.e. when hardware/software or other systems are involved. It was not a categorization of larger climate change initiatives, for instance… just where tech that’s supposed to get commercialized is involved, and where entrepreneurs and investors hope to make a return.
  • It forced the internal discussion of whether nuclear is a clean technology. While some argue nuclear has no place in cleantech, we opted to include it, as we’ve recently been made aware of nuclear-related innovations being pursued to derive power from non-weaponizable fuels, and other new R&D aimed at cracking that other historical nut of nuclear power: waste. But those are other stories.
  • It forced a focus on cleantech-related innovation. For instance, just because recycling is a category doesn’t mean that everything in the recycling industry is cleantech. Likewise semiconductors. Or hydro. But these areas are ripe for clean technology innovation, and there are new cleantech breakthroughs happening in each there today. Hence their inclusion.

Cleantech definition taxonomy (c) 2010 Kachan & Co.

click here to download the Kachan & Co. taxonomy in PowerPoint slides

After years of writing thousands of clean technology articles and reports, our team proposes this categorization as a cleantech category taxonomy. But consider this a ‘crowdsourced’ first draft. We’re interested in industry feedback before calling this done. Weigh in, and we’ll incorporate your best thinking in a final version we’ll publish on our website here a few weeks from this writing. We’ll then start using the final as a framework for other forthcoming cleantech information products, and invite you to use it, too.

(Credit: dozens of others’ frameworks were reviewed in this process, but special acknolwedgement to taxonomies from Cleantech Group, China Greentech Initiative, StrategyEye, Greentech Media, Skipso and Wikipedia, all of which informed our final structure below.)

In outline form, Kachan & Co's taxonomy of what fits where in cleantech:

  • Renewable energy generation
    • Wind
      • Turbines
      • Components, incl. gearboxes, blades, towers
    • Solar
      • Crystalline silicon
      • Thin film
      • Thermal
      • CSP
        • Thermal
        • PV
      • Organic
      • Nanotech
      • PPA providers
      • Systems
    • Renewable fuels
      • Grain Ethanol
      • Cellulosic Ethanol
      • Biodiesel
      • Biogas
      • Algal-based
      • Biobutanol
      • Hydrogen [when produced from non-fossil sources]
    • Marine
      • Tidal
      • Wave
      • Run-of-river and other new hydro innovations
      • Ocean thermal
    • Biomass
      • Wood
      • Grasses (e.g. miscanthus, switchgrass)
      • Algae, non-fuel
    • Geothermal
      • Hardware & systems
    • Waste-to-energy
      • Waste heat recovery
      • Anaerobic digestion
      • Landfill methane
      • Gasification
      • Plasma torching
    • Nuclear
      • New designs
      • Non-uranium fuels
      • Waste disposal
    • Emerging
      • Osmotic power
      • Kinetic power
      • Others
    • Measurement & analysis
      • Software systems
      • Sensor and other hardware
  • Energy storage
    • Batteries
      • Wet cells (e.g. flow, lead-acid, nickel-cadmium, sodium -sulfur)
      • Dry cells (e.g. zinc-carbon, lithium iron phosphate)
      • Reserve batteries
      • Charging & management
    • Fuel cells
      • PEM
      • DMFC
      • SOFC
      • MCFC
      • Zinc air
    • Thermal storage
      • Molten salt
      • Ice
      • Chilled water
      • Eutectic
    • Flywheels
    • Compressed air
    • Super/ultra capacitors
    • Hydrogen storage
  • Energy efficiency
    • Smart grid
      • Transmission
        • Sensors & quality measurement
        • Distribution automation
        • High voltage DC
        • Superconductors
      • Demand management/response
      • Management
        • Advanced metering infrastructure (AMI) & smart meters
        • Monitoring & metering
        • Networking equipment
        • Quality & testing
        • Self repairing technologies
        • Power conservation
        • Power protection
        • Software & data analysis
    • Green building
      • Design
        • Green roofs
      • Building automation
        • Software & data analysis
        • Monitoring, sensors and controllers
        • Metering
        • Networking & communication
      • Lighting
        • Ballasts & controllers
        • Solid state lighting
        • CFLs
      • Systems
        • HVAC
        • Refrigeration
        • Water heating
      • Consulting/facilities management
        • ESCOs
    • Cogeneration
      • Combined heat and power (CHPDH)
    • Electronics & appliances
      • Efficient power supplies
      • Data center virtualization
      • Smart appliances
    • Semiconductors
  • Transportation
    • Vehicles
      • Improved internal combustion
      • Hybrid ICE/electric
      • All electric
      • Rail transport innovation
      • Water transport innovation
      • Components
    • Logistics
      • Fleet management
      • Traffic & route management
      • Lighting & signals
      • Car, bike, equipment sharing systems
      • Parking management systems
    • Fueling/charging infrastructure
      • Vehicle-to-grid (V2G)
      • Plug in hybrids
      • Induction
    • CNG
      • Engine conversion
      • Storage improvement
  • Air & environment
    • Carbon sequestration
      • Carbon capture & storage
        • Geological
        • Ocean
        • Mineral
        • Bio capture, incl. algae
        • Co2 re-use
      • Geoengineering
      • Biochar
      • Forestry/agriculture
    • Carbon trading/offsets
      • Software systems
    • Emissions control
      • Sorbents & scrubbers
      • Biofiltration
      • Cartridge/electronic
      • Catalytic converters
    • Bioremediation
    • Recycling & waste
      • Materials reclamation
      • New sorting technologies
      • Waste treatment
      • Waste management & other services
    • Monitoring & compliance
      • Toxin detection
      • Software systems
      • Sensors & other measurement/testing hardware
  • Clean industry
    • Advanced packaging
      • Packing
      • Containers
    • Design innovation
      • Biomimicry
      •  Software
    • Materials innovation
      • Nano
        • Gels
        • Powders
        • Coatings
        • Membranes
      • Bio
        • Biopolymers
        • Biodegradables
        • Catalysts
        • Timber reclamation
      • Glass
        • Chemical
        • Electronic
        • PV
      • Chemical
        • Composites
        • Foils
        • Coatings
      • Structural building material
        • Cement
        • Drywall
        • Windows
      • Ceramics
      • Adhesives
    • Equipment efficiency
      • Efficient motors
      • Heat pumps & exchangers
      • Controls
    • Production
      • Construction/fabrication
      • Resource utilization
      • Process efficiency
      • Toxin/waste minimization
    • Monitoring & compliance
      • Software systems
      • Automation
      • Sensors & other measurement/testing hardware
  • Water
    • Generation
      • Desalination
      • Air-to-water
    • Treatment
      • Filtration
      • Purification
      • Contaminate detection
      • Waste treatment
    • Transmission
      • Mains repair/improvement
    • Efficiency
      • Recycling
      • Smart irrigation
      • Aeroponics/hydroponics
      • Water saving appliances
    • Monitoring & compliance
      • Software systems
      • Sensors & other measurement/testing hardware
  • Agriculture
    • Crop treatment
      • Natural fertilizers
      • Natural pesticides/fungicides
    • Land management
      • Erosion control
      • Sustainable forestry
      • Precision agriculture
      • Soil products/composting
    • Aquaculture
      • Health & yield
      • Waste management
      • Containment

Thoughts on how to improve? Please leave a comment on the comment thread below.

A former managing director of the Cleantech Group, Dallas Kachan is now managing partner of Kachan & Co., a cleantech research and advisory firm that does business worldwide from San Francisco, Toronto and Vancouver. Its staff have been covering, publishing about and helping propel clean technology since 2006. Kachan & Co. offers cleantech research reports, consulting and other services that help accelerate its clients’ success in clean technology. Details at www.kachan.com.

** New comments now turned off - thanks. A final version incorporating your feedback has been posted. **


This is the most comprehensive, well thought-out work I've seen yet to define cleantech. Congrats. Kudos for putting smart grid where it belongs: under efficiency.

That said, I'd consider making green building its own, standalone separate category--is all green building motivated by efficiency? And perhaps combine water and agriculture; they're both such modest categories when it comes to cleantech investment and innovation (albeit hugely important to us as a species) that maybe they should be collapsed into one.

But again, well done. Not an easy task. Shows a real grasp of the sector. Subject of a few late night arguments internally over pizza and beer?

You need to add a class of fuels that are drop in replacements. Companies like Amyris, LS9 and Virent, to name but a few are using non Cellulosic and non algae feedstocks to create green jet fuel, diesel and gasoline.

This is by far the fastest growing segment of fuels(algae perhaps included) as the Dept of Defense and major airlines all are creating demand.

This really should be combined with algae derived in your category, but renamed "drop-in fuels".

Dallas Kachan's picture

You and Sandor (above) also made similar points. Our oversight. Will correct and include. Thx!

Under the heading of Renewable Generation > Renewable Fuels you include three specific product types that all use similar technology platforms (grain ethanol, cellulosic ethanol, and biobutanol), plus one micro-crop that is used in multiple dissimilar technology platforms to produce multiple dissimilar products ("algal-based"). You do not include non-algae micro-organisms that can also be used in ways similar to some algae-based pathways. If the taxonomy is supposed to be a "classification for technologies," then you might want to build this piece of the hierarchy around elements like the following, recognizing that all of them are capable of using multiple specific feedstocks, and of delivering a variety of products for different markets:
- Macro-crop fermentation
> Grain starch
> Cellulosic
- Macro-crop gasification
- Micro-crop batch processing
> Algae
> Microbes
- Micro-crop continuous processing
> Algae
> Microbes

Hope that's useful ...

Excellent thought leadership, Dallas. The categories reflect a lot of thought. Overlaps are a challenge. For example, electric cars are facilitiating a smart grid infrastructure which you appropriately put in Energy Efficiency. Specific Level II, Fast Chargers, etc, probably belong in Transportation / Infrastructure. These are some thoughts about enhancing the Transportation category:

Vehicles – good start. If this is a global index, you might consider 120 million e-bikes to LEV in China, 1 billion bicycles globally, and new mobility.

Intermodal Mobility – add transportation smart apps to light-rail to high-speed rail

Services – include current logistics; add System Integration (e.g. Bosch, Eaton, ISE), ITS, vehicles as services (e.g. Car Sharing)

Infrastructure – add Smart Charging, battery switching. Added ideas:

Low Carbon Fuels – include CNG, LNG, Biomethane, downstream biofuels production, onsite hydrogen creation, etc. Added ideas:

I would encourage you to also look at the Wilder NASDAQ OMX Global Energy Efficient Transport Index.

IT heavily impacts clean transportation. Perhaps, we need a Cleantech & IT convergence index.

I hope your work leads to some interesting Indexes.

Every success!

Dallas Kachan's picture

John, your extensive background in this field is reflected in your comments. Thanks for taking the time to make this even stronger. Will incorporate your feedback into the final version in a week or two.

Dallas - a good effort here. I agree with John that the transportation category could use some further refinement. Specifically you may find the hierarchy at this website link useful http://www.skymetercorp.com/index.php?Itemid=226 (Global Impact - Slashing CO2 Emissions).

It specifically suggests the following hierarchy to reduce transport emissions:
1. Reduce total driving (highest/fastest impact)
2. Drive existing vehicles more efficiently per km
3. Make new vehicles/fuels more efficient (lowest/slowest impact)

The transport section has a lot on 3. vehicles and fuels. It has a bit on 2. efficient use of vehicles under the term of "logistics", but this catchall term ignores, for instance, the "Green Driving" techniques of firms like GreenRoad. Lastly, there is very little on 1. reducing total driving ... although some of the items under logistics like parking pricing (you call it parking management systems), or car/bike sharing could fit in here.

On a similar note, I remember power utilities more than two decades ago talking about conservation efforts and the concept of "Negawatts". Some of this was accomplished just by changing behavior. That sort of falls under your concept of "Smart Grid - Management", but the stress in this categorization on management of a large scale system rather than the power of pricing signals to change the behavior of individuals.

This is a great comprehensive list. I wonder if another branch should be incorporated however, along the lines of:

* Regulatory and environmental compliance (within each of the sub-topics)
* "Green" patent (& all intellectual property) management
* Scholarly, media, commercial and governmental reporting (of products, developments, research findings, grant applications)
* Lobbying for favorable tax codes and standards
* National and international standards development for fuel qualities, standardized measurements, etc.

In short, we'll still need a lot of those Communication Majors and GSA people working in the Cleantech field.

Dallas Kachan's picture

All these suggestions above feel like necessary and important parts of the various cleantech infrastructure/value chains. They're less obvious as categories for classifying clean technology innovation, however, which was the focus of this exercise. Nevertheless, this is important input. We agree with your conclusion: there's a need for skill sets above and beyond engineering in cleantech.

As the founder of Green Career Central and the author of Green Careers For Dummies, I've spent quite a bit of time wrestling with how to help mid-career professionals, students, and career counselors/coaching make sense of the emerging green economy.

I can imagine how much effort, thought, rethinking, re-categorizing, and debate went into this cleantech taxonomy! Thank you!

In my efforts to create a map of the Green Economy (www.greencareercentral.com/map) I went through 12 drafts over 2 years before I landed on my current version. (Note I say "current." I constant look at how to update, evolve, and strengthen my map. I've always know nthere would be another version...nothing in the emerging economy stands still for long.)

With your new taxonomy for clean tech as a reference, I'll be taking a new look to see how I can designate cleantech industries within my own map. Thank you again for your important contribution for investors and career seekers!

I also struggled with how to categorize waste.

Although we generally think of waste collection as resource management issue - tied into waste collection, recycling, and landfill management - it's time to see waste as a by product and an input of manufacturing and industry.

I ended up moving waste into the cradle-to-cradle manufacturing/industry cycle. The only way we can become accountable for the waste we produce and its impact is to talk about how to design, manufacture, reduce, reuse, recycle, and dispose of waste in a new way.

Waste that can be repurposed must be seen as a potential income stream for the manufacturer or the waste management company so that it is valuable enough to keep out of landfill. Innovations may come from utilizing waste streams that are readily available and inexpensive to obtain.

So much of our waste (residential, consumer, manufacturing, industrial) can be tied back to how products are designed, manufactured, and distributed.

Although probably not a cleantech application, building demolition and construction waste, which accounts for about 30% of landfill waste, is another important source of waste to consider in the big picture. Most likely it fits into the building cycle.

Hope these insights are helpful in your efforts to finalize your cleantech taxonomy.

Congrats - this is a direct ripoff of the confusing and convoluted frameworks already in the market. You'd think with a clean slate that you would have produced something more intelligible.

Dallas Kachan's picture

-This can't help but be influenced by other taxonomies in the market, yes. We acknowledge some of them above. Some of them get things right in some areas, in our opinion. But none have kept pace as the market has expanded and re-shaped. None felt comprehensive. Hence this proposal.

- Our version takes the number of high level categories down to 8, fewer and less convoluted than most others' high level takes on greentech/cleantech.

- Did you download the attached PowerPoint slides for a multi-page version of our proposal? Perhaps our charts are less convoluted than the long, bulleted list on this web page?

- If this work is unsatisfactory in your opinion, suggestions for how to improve?

Greetings! I've been dealing with renewable energy taxonomy for nearly 20 years now (for both NREL and DOE's Office of Energy Efficiency and Renewable Energy), and overall I think you've done a fine job.

Some minor nitpicks:
1) I'd add a wind measuring and forecasting bullet to wind. There's some interesting innovations going on there that are critical to the industry.

2) Geothermal deserves some subcategories ... I'd say exploration (although that opens the door to a bunch of oil and gas techs, too), power conversion (again, also applicable to other industries, including waste heat recovery) and hot dry rock, which DOE called Enhanced Geothermal Systems. HDR in particular is getting attention from Google and DOE right now, and there are some Australian firms beating their heads against the wall trying to make it work, as well (I wish them the best of luck, they need it!).

3) Smart Grid/Transmission should include a section on thyristors and other such devices to control the grid. Maybe call it "high-voltage control devices" or something like that.

4) Smart Grid/Management should have a bullet on cybersecurity.

5) Under vehicles, I'd combine the hybrid and all-electric categories into one called "vehicle electrification," since many of the same technologies apply to both (it's mainly a matter of degree). I also see some opportunity for innovation in engines for plug-ins, but I suppose that would fit under your improved ICE category.

My main gripe, however, is with the solar section. I think you should clearly separate PV and thermal technologies, as they have little overlap. And "nanotech" is just an enabling tech (it could be a subcategory under most of the categories in this taxonomy!); it shouldn't have it's own bullet. "PPA providers" are also an example of a bigger category that I'd call financing. And there are some innovations in capturing sunlight for direct lighting (using fiber optics and such), so that should be it's own category. So I see the solar part as more like this:

Photovoltaic techs
* Crystalline silicon
* Thin-film
* Organic
* Concentrating
* Module techs: electrical contacts, encapsulation, etc.
* Inverters
Thermal techs
* Non-concentrating thermal
* Concentrating thermal, including CSP

I struggle with the PV categories, though, since there are some wacky ideas out there that just might work, like antennas designed to capture solar energy. So maybe the "organic" category should be "organic and other"?

I hope this helps!