Coal seam gas (CSG) is gas that is trapped within the cores of unmined coal seams. The advent of recent drilling technologies has meant that it is possible to economically extract the gas without necessarily mining the coal deposit itself.
The CSG process
Once seismic data of the CSG reserves has been assessed and the resource is proven, drilling can commence to extract the gas. Drilling coal seams involves a series of vertical and horizontal wells through the coal seams with a view to fracturing the seams, dewatering and releasing the methane-rich gas. Generating power from the “˜coal gas’ in this manner is far less environmentally harmful than mining and burning the coal for power generation.
With most CSG projects it is desirable and economical to reticulate the coal gas to a natural gas pipeline; however it can take time to get the necessary approvals and certified reserves for such developments. Instead, some CSG producers have recognised the value in monetising their resource early and have utilised efficient modularised power stations to convert the gas to electricity.
Clarke Energy’s proven power station model has been designed to allow coal gas producers to begin generating power early. The successful model features a modular design, which facilitates the earliest possible generation given that work can start immediately upon award, saving critical design time at the front end. The model also allows steady augmentation to coincide with the development of the gas reserves and drilling program. This means that coal gas producers can begin generating with as little as 500 kilowatts and then grow this output to tens of megawatts as the gas wells come online.
The successful development of Clarke’s in-house pre-engineering solution has been demonstrated over the company’s portfolio of completed projects over the last five years. Dubbed the “˜cookie cutter’, the solution has been delivered for many clients for power stations in the range of 10-45 megawatts (MW).
Over the last four years, Clarke has completed turnkey power stations with a total output of more than 166 MW.
In November last year, Clarke completed construction of a 45 MW power station at Moranbah for Energy Developments Limited. This station is fuelled by waste coal mine gas from Anglo Coal’s mining operations, which would otherwise be wasted through flaring.
More recently, Clarke was contracted by Eastern Star Gas with the expansion of the company’s Wilga Park CSG operation at Narrabri. Installation of the first of
12 x 3 MW GE Jenbacher generator units is currently underway. This power station has been designed to accommodate a total of 36 MW of new generation, with the 3 MW units are being progressively installed as gas becomes available.
Other projects that Clarke has been involved in include:
* 21 MW Oakey Creek Power Station and 10 MW Glennies Creek Power Station for Envirogen
* 33 MW Daandine Power Station for Arrow Energy
* 21 MW power station at Moranbah for Dyno Nobel (now Incitec Pivot Group)