Reciprocating Engines working on the “Otto” or “Diesel” cycle have been used in power generation for many years. Small units can be purchased from local hardware stores for camping, boating etc. In the Utility Power Generation World Reciprocating engines are primarily used for black starting and backup. There use can also be determined by availability to cheap fuel. Reciprocating engines operate on the same fuels as a gas turbine but at higher efficiencies. Over the last year’s larger units to 20MW have been developed and installed returning efficiencies up to 49%. Diesel engines are generally more efficient than spark ignited types but also produce higher levels of NOx, SOx and particulates. Power plants based on Reciprocating engines are usually formed on a number of engine sets to allow for the maintenance requirements associated with piston engines. Reciprocating engines are excellent for rapid starting from small power sources which guarantees them a position on any system grid for black start and peeking operation.

The open cycle gas turbine and its technology has altered the provisioning of remote base load. They are ideally suited to provide remote area reliable power or Grid peeking operation. Having far fewer moving parts than the reciprocating engines the gas turbines typically return much lower maintenance costs. These units have operating in efficiencies from ~33% to >40% (Intercooled) which is combined with flexible fuelling options ranging from Fuel oil, Diesel and Gas. The engines work on the “Brayton” cycle and are very temperature and pressure dependent for output. Temperature stabilisation can be achieved by using inlet chilling coils. One drawback of some of these Gas Turbines is the high energy required to start.

Since the late 1980’s manufactures have worked to combine the “Brayton” cycle and “Rankin” cycle to provide combined cycle power plants. These consist of a standard gas turbine delivering ~33% efficiency however instead of ducting the exhaust to waste it is now passed to a Heat Recovery Generator (HRSG). The gas turbine exhaust is typically ~520°C mark allowing for significant energy recovery. This type of boiler consists of finned tubes to increase surface area and extracts the heat from the gas turbines exhaust in to water and steam. This steam is then passed to a steam turbine to create more energy with no additional steam input. Today's combined cycle plants can push 60% efficiency allowing for more energy per unit fuel and hence lower emissions. With today’s availability of gas, the CCGT plant has become the new base load choice. By utilising smaller gas turbines flexible plants.

While the burning of fossil fuels such as coal is deterred, there is an abundance of this fuel source leading to “Clean Coal” development. Early designed incorporated bed combustion moving through pulverising of the fuel to a fine powder. Feed water heating and steam extraction has also raised cycle efficiencies to the ~36% area. With new materials the cycle has again been modified by removing the latent heat required to false water to steam resulting in supercritical operation. Today’s ultra-critical pressure boilers are achieving >42% efficiency through the Rankin cycle.

With the plush to “Clean Coal”, One of the emerging developments is the Sub and Super Critical Circulating Fluidised Bed boiler (CFB). This coal boiler has the following advantages over its PC counterparts:

(a) A wide range of fuels can be used down to low grade municipal waste and biomass.

(b) Lower pollution is achieved as the combustion temperatures in the boiler are below 900 °C which reduces the generation of NOx gases. SOx gases are removed intra furnace by limestone injection.

(c) High combustion efficiency is attained by excellent combustion mechanism of circulating fluidization mode.

(d) Space Saving and highly maintainable due to the removal of separate desulphurisation and fuel milling plant. Accordingly, high maintenance items of equipment reducing the overall O&M cost.

With the ever-increasing emphasis on green energy and conservation of the earth’s environment. Generation utilities are looking to cleaner ways to produce reliable and flexible energy. The most common form of renewable generation currently commercialised is the wind turbine. These are now produced in variants up to 2.2MW per unit and can be seen in many countries. 2nd to wind turbines and at a march larger level are the hydro electrical power plants utilising either storage or run of river process. The largest in the world is the 3 gorges project of China. Another growing area of renewable generation is solar be this through photovoltaic (PV) or energy transfer. It is now common place to find houses in the world with kW of PV solar panels on the roof however each of these premises is still grid connected to cover periods of low sun or night time. Solar has also been used in existing CCGT cycles to provide additional heat credits and improve efficiency although these systems are not yet commercially viable in most countries. With the improvement in battery technology combinations of all the renewables can be engineered to provide 24/7 power. Gensrv is currently working hard with Solar Hybrid where we use battery grid controllers to maintain a 3-phase system and balance generation and load from battery, PV panels, reciprocating generation and wind turbines. These systems are ideal for micro grid implementation.

The team at Gensrv is always seeking new opportunity to achieve more with what is given. Our moto is that we must add value to all services we provide. Since the cost of fuel is the highest significant contributor to operation costing (OPEX). Fuel optimisation and energy waste are key areas to be addressed when looking at plant performance improvement. In some cases, the basics such as mill maintenance and condition along with PF fineness can have significant cost impacts on base fossil plants. Indicators such as stack and ash analysis assist in the determination of poor combustion and therefore fuel / cost loss. For reciprocating plants conditions such as poor atomisation of fuel through bad injectors may be a contributing factor or in gas turbines compressor cleanliness and filter condition. In all cases Gensrv will assess and monitor your asset to determine areas for improvement to give reduced costs or improvements in availability. Paramount to the process is the effective use of the maintenance dollar. GenSrv is competent with most modern Enterprise Resource Planning (ERP) packages such as SAP, Mincon MINS, MEX and can utilise these IP and history tools to streamline maintenance effort and cost. The group has Thermal and electrical modelling tools which allow the determination of optimum conditions and therefore determination of loss. Why not add these impacts to your Human Machine Interface (HMI) so that staff see the real impact of operating off design.

In some cases, the method of operation by the grid system and the application of spinning reserve has a detrimental impact to heat rate and therefore cost. It is therefore imperative the spinning reserve is best managed to utilise the most cost effective assets to provide such service. In short know your Short Run Marginal Cost (SRMC).

With years of experience Gensrv can take a green field asset and develop all the plans, procedures and policies required for its operation over the proposed lifecycle and supply, customise and propagate the plants ERP system. We are also able to supply skilled staff to manage assets of different designs and are always keen to negotiate performance based O&M contracts with our clients. Gensrv uses methodologies such as condition based assessment to ensure our maintenance costs are reduced year to year excluding known CAPEX expenditure. With regard to brownfield assets and following due diligence the existing methodologies can be reviewed and any improvements identified and ratified then implemented. In all cases the key drivers are O&M cost in relation to delivering the facility generation warranties to clients and their upstream commitments.

Data is generated and utilised so many times during an assets development right through to decommissioning. Why is it that this data has to be collected again and again during an assets lifecycle? Gensrv believe all data needs to be captured and made really available to all whom need it during all phases of the project. We further believe this data should only ever need to be entered once. Based on hierarchical system tagging such as the power plant specific KKS system all our data and documentation is connected to and trapped with the equipment’s tag in asset management databases. These databases start life during conception and feasibility, date entry only once.

Key to any group is the staff within that group. All Gensrv staff are used to working with local teams and where required transferring knowledge and know how. Underpinning this is the ability to hold training and education courses for asset owners on all aspects of operation and maintenance as well as asset management and business process. With courses based on engineering / business foundations we are able to tailor each subject to a client’s specific hardware or system.

For our Operation and Maintenance contract Gensrv employs a system of “Competency Management” as experience has dictated that multiple short courses with written and oral exam serve much better to impart knowledge than one of block sessions. The Gensrv “Power Competency” suite of training modules is tailored to advance most staff in the areas of power facility business and engineering / operations management.