Envirogen Coal Mine Gas Philosophy

Waste Coal Mine Gas Power Station Design Philosophy

Envirogen has chosen to use individual containerised 1 MW and 3 MW reciprocating gas engine generator sets
for its waste coal mine gas power stations, to allow maximum efficiency and flexibility. Using this proven technology
ensures that generation can be undertaken over a broad range of gas qualities at different mine sites while also enabling cost
effective maintenance programs and operational efficiencies.

Gas Engines
The current operational power stations use 1 MW and 3 MW, Austrian built, GE Jenbacher reciprocating engines.

The generators are individually enclosed in locally fabricated steel containers complete with noise baffling and fireproofing. The engine enclosures have been custom designed to suit specific site requirements including cooling and ventilation, to ensure that there is no derating at high ambient air temperatures. Each container is fitted with its own carbon dioxide deluge fire fighting system and noise abatement measures are also incorporated to meet stringent Environmental Planning Authority conditions.

Gas Handling Systems
Gas filters, blowers and pipework have been designed specifically for each power station based on gas specifications for that site. Gas filtration has been designed to ensure that particles as small as 5 microns are filtered out, with easy cleaning of the filter system that minimise down time. Blower type and sizing and gas pipework are designed to ensure a moderate level of redundancy whilst ensuring that capital cost and auxiliary electrical loads are minimised.

Electrical
High voltage transformers are inherently reliable and the power station design consequently has one generator unit step up transformer shared between two generating units. This is considered an effective balance between cost and risk of failure. These unit transformers step up the generator voltage from 415V to 11kV. An indoor 11kV busbar arrangement then links all generator sets to a common busbar. The export voltage of 33kV or 66kV is then achieved by way of a single step up station transformer.

Fully Computerised Control Rooms
A fully automated and computerised control room operates all power station plants automatically, 24 hours per day, 7 days per week. It includes automatic control of the gas engines, gas delivery pressures and quantities, blower control, System Control and Data Acquisition System (SCADA) for analyzing and reporting power station performance and alarms either locally or remotely. The stations are managed throughout normal business hours with staff on call and remotely linked to the stations SCADA system for any out of hour requirements.