Biogas Generator (CHP)

Overview

A biogas generator turns the methane from a digester, landfill or wastewater plant into both electricity and useful heat. Rather than flaring the gas, it burns it in a reciprocating engine driving an alternator, and then captures the heat the engine would otherwise waste, from its cooling jacket and its hot exhaust, into a hot-water loop. Running both products together is what makes the set efficient: a third of the fuel's energy becomes electricity, and most of the rest is recovered as heat, so very little is thrown away.

How it works

Cleaned fuel feeds the Gas Engine, a spark-ignition unit whose pistons drive a crankshaft in a cast block. Biogas is not pipeline gas, it is wet, low in energy and laced with corrosive hydrogen sulphide, so it first passes through the Gas Treatment Skid skid, where a filter strips the sulphide and a blower lifts the gas to engine pressure. Inside the engine, the Fuel-Gas Train meters the gas and blends it with air in a venturi mixer, the Turbocharger boosts the charge, and the Ignition System fires a spark plug in each cylinder.

The crankshaft turns the Synchronous Alternator, a brushless synchronous machine whose voltage regulator holds a steady output as the load swings. That power cannot simply be dumped onto the grid: the Control & Synchronising Panel governs engine speed, watches the grid voltage and phase, and only closes its synchronising breaker once the alternator is matched, all while its protection relays stand ready to trip on a fault.

Heat is the second product. The Cooling & Heat Recovery carries coolant through the engine and through recovery exchangers that pull heat from the jacket water and the exhaust into a building or process loop, with a radiator to shed whatever heat the site cannot use. The whole gen-set sits inside an Acoustic Enclosure that silences it and keeps the weather out.