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I'm looking at a biomass feasibility proposal for a food product manufacturer that proposes to use approximately 3 tonnes of fuel per week to create hot water that is then fed into a boiler to produce steam.

The project is not that straight forwards as it proposes to use a non-standard fuel (briquettes made from egg cartons). The main barriers for progression that I have noted include:

1. Burning the material
2. The disposal of ash
3. The reliability of biomass burners when using this material

1. As far as I’m aware cardboard and paper products (including egg box briquettes) are not eligible for the same exemption from the Waste Incineration Directive (WID) as waste wood. This means to burn the fuel would require WID approval from either the Environment Agency or Local Authority depending on the volume of fuel being burnt.

2. Due to the nature of the material the ash produced falls under the waste disposal regulations. This is partly because the preferred route of disposal for card products is recycling and not energy recovery. It is also because within the material there are usually a wide range of contaminants including bleaches (ie chlorine), fillers, dies, pigments, finishes, adhesives, etc. This makes beneficial use of the ash difficult and in some cases the ash may be classified as hazardous (even more barriers!). There are a number of new waste exemptions to allow certain forms of waste, including ash from burning untreated wood and vegetable waste, that have been brought in by the Environment Agency but I can find no reference to paper / card products.

3. Although biomass is now an established sector the majority of burners use fuel such as wood chip or pellets. To my knowledge the reliability of a burner using cardboard briquettes is not heavily tested.
If the proposal went ahead the business could create 3 tonnes of fuel per week to be used as fuel.


Does anyone know of a manufacturer that specialises in non-standard biomass fuel burners?
Also does anyone have any clever ideas for the disposal of the ash?

I'm no engineer, but I suspect that standard biomass boilers would need considerable changes to burn a low density fuel like cardboard briquettes safely, efficiently and reliably. I'm also not sure how easy it would be make the briquettes sufficiently uniform in size, shape and composition.

I cannot see any boiler manufacturer wanting to build a one-off boiler with the considerable development and certification it would require for what sounds like an almost unique fuel source.

The briquettes would need a very low water content to burn efficiently enough to meet smoke emissions regulations. The project is obviously intended to extract heat from a low grade waste product at relatively low temperatures. The best boilers raise the combustion to nearly 1000C.
Even at these temperatures, the contaminants you list risk producing dioxins as a side product of inadequate combustion. These are deadly toxins.

I'm not sure you aren't getting out of your depth on this project...

http://www.dioxinfacts.org/sources_trends/the_way.html

Rather than going for briquettes which I would think would involve wetting the card, pressing it and then drying it again before burning, why not use an established technology like pellets. There are plenty of off the shelf machines that could be used to pelletise the card and plenty of proven pellet boilers of all sorts of sizes to burn the stuff.

Don't try to reinvent the wheel.

You would probably have to have a test batch of fuel chemically tested before burning so that the contaminants could be identified and the waste products predicted. If you were within safe levels of chlorine and other dangerous contaminants you could go ahead with the project.

Pellets are made from all sorts of biomass even including pampas grass so I wouldn't have thought card would be a problem.

I would have thought that the best way to use old egg cartons is to make new egg cartons from them.