Clearfleau's bio waste treatment heat and energy solutions

Combined heat and power generation

Anaerobic digestion is a valuable source of on-site renewable energy.  The biogas produced by anaerobic digestion can be used to generate electricity or fed to on-site boilers. In addition,  treated biogas can be fed directly into the gas grid. 

At present, on most anaerobic digestion plants, renewable electricity is generated from combined heat and power (CHP) engines, along with surplus heat.

Electricity generated can either be used on site (to replace bought-in power), or sold to the national power grid at a premium over purchased electricity costs.  By generating renewable energy, on-site anaerobic digestion will reduce treatment costs and replace fossil fuel derived energy and reduce the carbon footprint of the site. 

The renewable electricity Feed in Tariff (FIT) was extended with two additional FIT bands in late 2011, to provide higher rates for smaller scale AD plants. The new bands are set at 14p per kW for plants producing less than 250kW and 13p for 250 to 500 kW, and 9.5p per kW (for plants that generate more than 500kW), plus about 3p per kW for electricity that is exported to the grid. There is likely to be some regression for FIT payments for plants that are completed after April 2015. 

To encourage the use of renewable heat, the Renewable Heat Incentive (RHI) was introduced in November 2011. This provides a payment of 6.8p per kW of surplus heat for anaerobic digestion plants producing up to 200kW of thermal energy that is derived from a CHP unit or for biogas injected into the gas grid.

On-site liquid AD has a significant advantage over aerobic effluent treatment. In addition to reducing the site’s energy and treatment costs, it has the potential to generate significant revenue from these incentives.  

Summary of Incentives (new bands with higher rates for smaller AD plants)

• FIT - Feed in Tariff - for smaller AD projects - payable monthly index linked - 20 year duration
• RHI - Renewable Heat Incentive – 6.8p < 200kW thermal
• LEC - Levy exemption certificates - require Ofgem registration - negotiated with generators 
• Site Power – reflects the cost saved when the renewable power is used. The actual figure will depend upon the cost of power pertaining on the site. 

Clearfleau is working with EnerG a leading provider of CHP generators. The CHP unit is tailored to expected biogas flow. To offer greater flexibility, Clearfleau can advise its clients on the lease or hire of the CHP units. 

The energy generated on a specific site will depend on the biogas potential of the feedstocks. This can be assessed on our model and verified with a laboratory trial or by using the mobile anaerobic digestion trials unit (Small Scale Production Plant - SSPP).

Clearfleau’s Anaerobic Plants are tailored to the specific waste stream and can be installed on a confined site. Based on the biogas potential, the appropriate CHP unit is selected to meet output and finance requirements. 

For more information and to arrange a site visit, please call 0844 477 6292 or email info@Clearfleau.com