Recovering Energy From Biogas - A Comparison of Available Technology

Bioenergy – which includes the production and utilisation of biogas from anaerobic digesters to produce electricity and heat, is becoming an increasingly important technology. As a result, biogas is a valuable source of fuel and the measurement, handling, cleaning, and utilisation of biogas is now at a more advanced state than ever before. Large suites of technologies are now on the market, presenting water utilities with a large array of options from which to select an appropriate solution.Recovery of energy has been dominated by recovery of heat via hot water boilers and heat exchangers. However since the introduction of Renewable Obligation Certificates (ROCs) in the UK, this has introduced the opportunity to deliver greater revenue savings whilst delivering heat recovery and electricity generation from biogas (Combined Heat and Power) CHP. This has shifted the emphasis towards recovery for energy as electricity and utilisation of waste from the generation process.Anglian Water is a major UK water utility, and in late 2003 started an investigation into a programme of works to exploit the opportunities for renewable energy and Energy Efficiency. This programme of works to design, specify, procure and commission renewable energy generation from anaerobic digestion with CHP installations followed a detailed feasibility study of 8 sites within Anglian Water. CHP implementation forms a strategic part of the Anglian Water Energy programme.This paper details some of the methods, equipment, testing and analysis applied both in the feasibility of, and implementation of this CHP programme. In addition a number of development initiatives, which were carried out as part of the CHP programme, encompassing gas cleaning and the evaluation of alternative technologies to reciprocating engines are discussed.