Biomass Combined Heat and Power (CHP) Systems


What is Biomass Combined Heat and Power (CHP) Systems?

In a biomass CHP system, the input fuel is biomass, typically wood chip or wood pellets.
Biomass CHP is particularly useful when the site is off the mains gas grid and where biomass fuel is readily available.

How does Biomass Combined Heat and Power (CHP) Systems work?

Small-scale biomass CHP boilers usually rely on pyrolysis (heating the fuel in the absence of air).

This produces syngas which is a mixture of hydrogen and carbon monoxide with a little carbon dioxide.

This gas is fed through a spark ignition engine, which in essence is the same as a gas-powered CHP unit.

The goal is to produce ‘clean’ gas as the carbon released from burning the biomass is roughly equal to what was absorbed during its growth.

Maintenance of small-scale biomass CHP is far greater than with mains gas powered CHP. Medium and large- scale biomass CHP systems tend to use steam to drive a turbine or Organic Rankine Cycle (ORC) that uses a
turbine driven by gas which boils at a lower temperature than water.

Both are mature technologies with excellent durability and reliability, which call for far less maintenance than is required for gasification CHP.

While most gas-powered CHP units can ‘modulate’ (respond to reduced electrical or heat load, usually to around 50% of peak output), biomass CHP boilers will run at maximum output consistently – they cannot run on part load. As a result, the ideal biomass CHP project is for the unit to provide a base load of electricity and heat, with the unit running for as close to 8,000 hours as possible.

How are Biomass Combined Heat and Power (CHP) Systems applied to a building?

Small scale (<100kW) and micro-scale (<15kW) biomass CHP are particularly suitable for applications in commercial buildings, such as hospitals, schools, industrial premises, office building blocks, and domestic

Optimum system design and implementation is crucial for cost-effective operation and it is established that the best economic performance come about with high load factors when the maximum amount of both electricity and heat sold on-site is maximised.

Biomass CHP systems need to have access to a reliable fuel supply, like a managed woodland or sawmill, as well as the ability for vehicles to deliver the fuel to the site. It is important that the fuel provided is of high quality with a very low moisture content to achieve the best results (wood chip typically has less than 15% moisture content).

Fuel costs are central since when considering the levelled cost of electricity and heat production, ongoing running costs far outweigh capital investment. Thus, it is imperative before considering investment in a biomass CHP system to ensure that the right fuel can be sourced locally.

Space is also a consideration, as the site will not only need space for the boiler, but also space to store the fuel.
The three-step process to net zero energy
OnGen offers a three-step process to public sector organisations. Steps can be done holistically or separately.

Step 1:

Reduce energy consumption:

With OnEfficiency, we can help you identify where and what you can do to reduce energy consumption and improve energy efficiency.

By becoming more energy efficient, carbon emissions for your organisation will begin to reduce, along with the cost of energy.
OnGen Expert

Step 2:

Consider onsite renewable energy and battery storage:

With the OnGen Expert, we can help you explore the feasibility of generating and storing your own energy via a range of onsite renewable energy generation sources, like solar PV and heat pumps.

Switching to generating renewable energy onsite reduces the demand for grid-supplied energy, lowering the cost of energy bills, gaining resilience to grid fluctuations and reducing carbon emissions.

Step 3:

Switch to zero-carbon energy suppliers:

With OnSupply, we can help you find the cheapest green energy tariffs for any grid-supplied gas and electricity demand.

Eliminate the remaining energy-related carbon emissions for your organisation.

Your organisation will be assigned a dedicated account manager, who will offer training support and guidance. Additionally, if your organisation is struggling for time, the Managed Service, where assessments are conducted by the OnGen team on your behalf, can be a great option.


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Case Study

“By assessing solar capability using the OnGen Expert software, we have been able to identify 4,000 tonnes of potential carbon savings in our city-centre building stock. OnGen has made it simple and easy for us to demonstrate potential energy costs savings of £2.9 million across the lifetime of potential onsite renewable installations. The OnGen Expert software has shown us the potential of onsite generation at a fraction of the cost of traditional assessments/consultants.”

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