High Temperature Combustion Technology


One of the most important steps in applying CSS Renewables High Temperature Combustion is a thorough understanding of the physical and chemical properties of the feed material. The properties of biomass feedstocks can vary significantly, meaning it is highly beneficial to clearly define the particular material for your application. CSS Renewables’s High Temperature Combustion technology is highly flexible and able to process a wide variety of feedstock material, so a clear material characterisation allows the process to be tailored to your feedstock.


Feedstock material is typically characterised by its chemical and physical properties, commonly comprising of those listed. Materials handling of the feedstock and the solid combustion products is directed by the physical properties of the material, including how to introduce the material to the combustion process. The chemical properties of the material directly influence the combustion process, including the thermal process requirements and the nature of the combustion products.

Physical Properties

Bulk and Dry Solid Densities

Particle Size Distribution

Form and Flowability

Amount of Free Moisture

Chemical Properties

Combustion Characteristics, including heating value

Composition: Proximate and Ultimate

The composition of the feedstock is usually reported as proximate and ultimate analyses.

Proximate Analysis

The proximate analysis provides the feedstock composition based on its pyrolysis characteristics, reported as mass fractions of moisture, volatile matter, fixed carbon and ash.  The analysis is determined as follows


Material is dried in an oven at 120 to 150c, driving off any moisture as steam.


Material is heated to temperatures on the order of 500 to 900c in an inert atmosphere such as nitrogen. Organic species volatilse and are removed from the sample.

Fixed Carbon

The remaining solid material is heated in excess air or oxygen, causing combustion of the remaining carbon material to carbon dioxide.


The remaining solid material, typically comprising silica and iinorganic oxides.

Ultimate Analysis

The ultimate analysis reports the biomass composition based on the individual elements it contains.  The ash fraction of the material can also be represented as an ultimate analysis.  The ultimate analysis will typically detail the composition of the major elemental components (carboon, hydrogen, oxygen, nitrogen) and usually minor components (silicon, chlorine, sulphur)

Business Case

In order to finance a project, it needs to have a viable business case. In order to build a successful business case a clear understanding of all of the revenue streams and operating costs and to understand how this relates to the capital cost of the project.


Depending on the type of plant you are building there are a number of potential revenue streams from an CSS Renewables plant.


Electrical Generation from the generators.

Gate Fees

A fee paid to take delivery of a waste product.


Some industrial consumers may be willing to pay for heat collected from the exhaust of the engines or kilns.


We can modify the system to provide electrical output to the latest Hydrogen production systems.

Government Incentives

In certain jurisdictions then extra payments can be received from the government for either the production of renewable energy or from the reduction of waste.

Operating Costs

There a several areas of potential cost in the operation of an plant designed, manufactured and delivered by CSS Renewables. Not all of them will always apply but each should be understood and assessed to properly develop the business model:


The biggest cost of running an CSS plant is the man-power to operate it. Operating hours and plant configuration can dictate the number of people required for this. You should typically look at annual operating hours of 8,000+.

Parasitic Load

The plant requires some of the electricity that it produces in order to run the plant. This needs to be subtracted from the gross power output. Think about conveyors, pumps, ID fans etc.


While CSS plants normally run off the principal fuel supply (RDF, SRF, Biomass etc) they do require a fuel for start-up after a period of maintenance or outage. This fuel is typically diesel, natural gas or LPG but alternative fuels can be used as well.

Maintenance & Spare Parts

All plants require spare parts and specialised service in order to keep operating.


Cost of transporting feed to the site if applicable or waste streams away from site. You will produce waste streams from the process. You should think about bottom ash (IBA) and pollution control system residues mainly.


All plants use certain quantities of consumables and these need to be assessed and valued.


It is normal that your operation has its own waste streams but you may also wish to buy feedstocks that assist favourable operating conditions.

Water Purchase / Disposal

Depending on the plant set-up you may find that you could be a net user or consumer of water. Excess water needs to be treated and disposed of while a water shortage will need to be sourced.

IBA & Pollution Control Residues Disposal

Depending on the plant set-up you may find that you could be a net user or consumer of water. Excess water needs to be treated and disposed of while a water shortage will need to be sourced.


In some cases, where there is no secondary market for the residues then it will need to be disposed of to landfill or specialist contractor.


There are many technology options available given a particular site, feedstock, jurisdiction and environment. CSS Renewables are the distributors for Hurst Boiler Inc for all combustion systems and R&R Beth for all post-combustion pollution control technologies. We believe we offer one of the most flexible options available and it suits many sites and locations.


Our team in the UK will work with you to recommend the best configuration for your plant given your plant profile and your budget.