Tuesday, 25 January 2011

The various flavours of torrefied biomass fuel

In the Petroleum Industry, hydrocarbon fuels come in various "flavours", and various grades in each flavour.

lets see . . . There's Gasoline, both regular and high octane; Diesel; Kerosene; Jet Fuel; Bunker C; heating Oil, and assorted blends (Bio-Diesel, Gasohol, etc.)

Each fuel has specific chemical and physical properties for the job at hand. Torrefied biomass is no different.

As we progress along the fuel validation path, we have come to learn that there will be several different "Grades" of torrefied Fuel. Some will be suitable for small biomass boilers; others for large Utility burners, and still others for Industrial processes (like Cement Manufacturing).

The problem is, that there is no "one size fits all" solution. If you take wood chips designed for a pulverised fuel injection burner, and try to feed them into 500 kW chip boiler, the results are, at best disappointing - at worst - catastrophic. By the same token, a fuel that works perfectly well in a Cement kiln, would clog up a Utility boiler faster than you can say alkaloid deposition.

There's only one TINY problem associated with defining the various Grades of fuel. That is, we can no longer rest on our laurels as experts in thermodynamic and chemical processing; we now need to completely understand combustion. (And here - I thought that once we cracked the torrefaction process we would be finished. How wrong we were.)

Developing a fuel that is all things to all men is roughly akin to genetically engineering an animal that is part Pig (for bacon and ham); part chicken (for eggs and meat); part Cow (for milk and steaks); and part fish (for Omega 3, and other good stuff). Somehow, it just doesn't seem possible. I think it might be easier to grow a fruit tree that has apples, pears, peaches, plumbs, oranges and avocados on it. (And actually - through the magic of grafting, my father was able to successfully grow one that had 3 varieties of each of the first 2 - but that's another story.)

But I digress . . . Back to the business at hand . . . . . .

In our never ending quest to add clarity and relevance to the market, below is an outline of what we see as the primary Grades of Torrefied Biomass Fuel.

  1. Smokeless Chips. (SC) This grade, is designed to replace standard wood chips in small to medium scale biomass boilers. It has been processed to a point of having most of the PAH's removed, (these, if you care, are Polycyclic Aromatic Hydrocarbons, and not very nice at all) but hasn't been processed to the point of being physically altered enough to become friable and fragile. Now the benefit to this, is really measured in improved Air Quality. Many jurisdictions aren't in love with the emissions from the ever increasing number of chip boilers being installed. Just as, in the UK, the transition from coal to "smokeless coal" in residential and commercial buildings was mandated many years ago - there will be a transition from chips to Smokeless chips in the years to come. We'll all breathe a little easier because of it.
  2. Pulverised Fuel Injection (PFI) By far and away, this will be the predominant fuel manufactured from Biomass. Within this grade, will be three varieties: "VW" (Derived from Virgin Wood); "AR" (derived from Agricultural Residues); and "RM" (derived from Recycled Material) Each fuel will carry its own credentials, in terms of environmental impact; embodied energy and sustainability. Again, utilisation will be at the whim of the local authorities, who will control utilisation and acceptability, based on their own unique views.
  3. Industrial Process (IP). This fuel would be specifically designed for the Cement, Steel and Glass manufacturing industries. Those boys use a LOT of energy (after all - to make these things - you need to melt rocks!) and want their fuel to have an energy content capable of heating a furnace to about one third of the surface temperature of the sun. Now don't get me wrong - I use as much glass and steel and concrete as the next guy, but BOY, that's a hot flame!
So, there you have it. Just when I think we've gotten to our destination, we learn that it is merely just another station stop on the way. Sometimes I get the feeling that we're 90% finished - with 90% to go.

If anyone would like to discuss the detailed "science things" behind this, feel free to contact me.

Jumping out of the frying pan, into the fire . . . . .


1 comment:

  1. Dear Richard,

    You make an interesting point there. And i guess as more and more different feedstocks are being torrefied the more difficult the characterization will get.

    I think it's important that any characterization should tackle it from the user perspective. As you rightly try to do.

    This is different i think from how the fossil fuels were characterized as many types of fuel were initial by-products of the cracking process and the process was formed by finding a suitable end use to a by-product (waste product).

    You mention that the torrefied characterization process will look at the different needs:
    - domestic boilers
    - co-firing
    - Industry power plants (cement)
    This results that the feedstock requirements do not differentiate along one technical axis (for example: carbon chain length) but across multiple.

    You mention emissions in the smokeless chips, feedstock type in PFI and energy content in the industrial process.

    These to my opinion are perquisites for the different uses and not so much a categorization of the fuel itself.

    Maybe it would be good to combine the end-use differentiation with the different technical characteristics that it requires for all three parameters you mention.

    Kind regards,