Biomass Combined Heat and Power (CHP)

Biomass Combined Heat and Power (CHP) systems simultaneously generate electricity and heat. This is achieved by using gases or heat from biomass boilers. The remaining heat is typically used in greenhouses or similar processes.

CHP systems are appealing due to their ability to qualify for subsidies. These subsidies apply to both the heat and electricity produced. This makes them a promising investment for areas with consistent heat demands.

Biomass CHP installations are often driven by the need for heat. These systems typically produce more heat than electrical power. The electricity generated can either be used onsite or exported to the grid.

Gasification in Biomass CHP

Gasification is a process in which biomass is converted into flammable gas. This gas powers an internal combustion engine to generate electricity. A 2:1 heat-to-electricity ratio is typical for such systems.

Clean gas production is crucial to avoid engine issues. For this reason, high-quality fuels like wood pellets are often required. Gasification is best suited for small-scale applications.

Despite its benefits, gasification has high maintenance costs. This, combined with the need for high-quality fuel, can limit its use. However, its small footprint and scalability make it an attractive option.

Steam Turbine Biomass CHP Systems

Steam turbine systems use standard combustion principles to produce steam. This steam drives a turbine to generate electricity. These systems can use a wide variety of biomass fuel types.

One advantage is their flexibility in fuel choice, including cheaper options like wet wood. Steam turbines are highly incentivized through government subsidies. They can produce both electricity and high-temperature heat.

However, the high operating costs of steam turbines may be a drawback. They also have a high initial investment. Yet, their efficiency and versatility make them a solid option for larger-scale projects.

ORC (Organic Rankine Cycle) Turbine Systems

ORC turbines operate using organic oils instead of steam. These oils work at lower temperatures and pressures, making them simpler to maintain. ORC systems can provide heat ideal for greenhouse heating.

The ORC system offers around 17% electrical efficiency, which is higher than steam turbines. Additionally, it performs well under partial loads. These systems can be scaled for smaller or larger applications.

Despite the advantages, ORC systems have a low electricity-to-heat ratio. They also come with a high initial cost and take up significant space. However, they are easy to operate and ideal for smaller-scale biomass projects.

Challenges in Using Biomass CHP

One challenge with biomass CHP is its flue gas composition. Unlike gas-fired CHP systems, biomass produces different flue gases that require specialized cleaning systems. The absence of an affordable cleaning system has hindered widespread adoption.

Efforts are being made in Canada and Europe to overcome this issue. Systems like the amine scrubber can separate CO2 from other gases. This innovation could make biomass CHP more attractive for growers in the future.

What is Combined Heat and Power (CHP)?

Combined Heat and Power (CHP) is a system that simultaneously generates electricity and usable heat from a single energy source. It increases energy efficiency by capturing heat that would otherwise be wasted during electricity generation. This process makes it more efficient compared to conventional power generation, which often wastes excess heat.

What is a Biomass CHP Plant?

A Biomass CHP plant uses organic materials, such as wood, agricultural residues, or other types of biomass, to produce both heat and electricity. The plant converts biomass into energy through processes like combustion or gasification. The heat produced is used for industrial or domestic purposes, while the electricity can power homes, industries, or be sold to the grid.

What is the Efficiency of Biomass CHP?

The efficiency of Biomass CHP plants varies, but typically, the overall efficiency ranges from 60% to 80%. Electrical efficiency alone tends to be lower, often between 15% and 30%, while the rest of the energy is utilized as heat. Combining heat and electricity generation boosts the system's overall efficiency compared to separate heat and power generation.

How is Biomass Used to Generate Heat and Electricity?

Biomass is used to generate heat and electricity by burning organic materials to produce steam or gas. In a biomass CHP plant, the biomass is burned or gasified, producing heat to generate steam, which powers a turbine to produce electricity. The leftover heat from the process can be used for heating buildings, greenhouses, or industrial processes.

How Much Energy Does 1 Ton of Biomass Produce?

The energy produced by 1 ton of biomass depends on its type and moisture content. On average, 1 ton of dry biomass can produce about 2 to 3 MWh (megawatt-hours) of electricity or heat. The energy output varies with the quality of the biomass and the technology used in the plant.

Is Biomass Energy Cheap?

Biomass energy can be cost-effective, but its cost depends on various factors, such as feedstock availability, technology used, and location. While the initial setup costs for biomass CHP plants can be high, government subsidies and the availability of local biomass can reduce operational costs. Over time, it can be cheaper compared to fossil fuels, especially in regions with abundant biomass resources.