Kipevu 2 - right first time6 May 2002
Successful independent power projects are primarily dependent upon being built on time, within budget, and achieving all performance targets. The recently inaugurated 74 MW Kipevu 2 diesel power project in Mombasa, Kenya, can truly claim success on all fronts. Graham Dilliway, PowerConsult International, Horsham, UK ([email protected])
On 14 March 2002, President Moi of Kenya formally inaugurated the 74 MW Kipevu 2 power station in Mombasa. During the seven-month period since the start of commercial operation, the plant has produced over 355 GWh at an availability of more than 94 per cent, exceptional for medium speed diesel plant.
Kipevu 2 entered commercial service on 3 September 2001, less than 13 months after first breaking ground. It increased the thermal generation capacity in Kenya by almost 25 per cent. During six weeks of exhaustive testing over 77.5 GWh were exported to industrial, commercial, and residential consumers.
The plant was built on time, within budget, and fully met performance expectations because every member of the project team, client, engineers, manufacturers, and contractors, all understood and produced what was expected of them.
The basic management strategy of being 'right first time' throughout the development and implementation of the project was achieved by:
• Precise definition of all project objectives: commercial, technical and financial, during contract negotiations.
• Zero project change, from the start of construction through to completion of commissioning.
• Zero accidents and environmental incidents.
• Selection of manufacturers and contractors with proven products and excellent safety records.
• Commitment by each management team to all project objectives and the means of achieving them.
• Contingency plans for any issues outside the direct control of the project team.
• Detailed project plans and schedules with clearly defined and achievable milestones.
Development of the Kipevu 2 project started in 1996, with an international competition to build, own and operate a 74 MW independent power project (IPP) in Mombasa.
Under IPP arrangements, the successful tenderer guarantees the availability, production and price of electrical power, all in exchange for a long term power purchase agreement (PPA) from the national utility, in this case the Kenya Power and Lighting Company Limited (KPLC).
The financial penalties on the independent power producer are severe for failing to achieve plant availability, power output, and fuel efficiency.
Tsavo Power Company Limited was the successful tenderer, with the power plant supplied by Wärtsilä Finland Oy, and operated by Wärtsilä Eastern Africa Ltd.
PowerConsult International of the UK was appointed owner's engineer, to ensure the plant would be designed, constructed, and operated in accordance with quality, performance, health and safety, and environmental management obligations imposed by the PPA, the Kenya Environment Secretariat, and the World Bank Group.
The commitment to being 'right first time' obliged PowerConsult International and Wärtsilä to fully define and agree all technical and commercial aspects of the project before placing any engineering, procurement or construction contracts. This work included the design of the electrical and operational interfaces between the Kipevu 2 plant, the adjacent power plants, and KPLC's 132 kV power transmission and control system.
PCI engineers and Wärtsilä Finland Oy developed a highly efficient and extremely reliable plant design in response to performance penalties in the PPA. Seven Wärtsilä 18W38 medium speed diesel engines form the heart of the plant, and dedicated auxiliary systems and duplicated components provide an operationally independent capability for each generating set.
Auxiliary systems can be replaced or repaired without shutting down an individual generating set or reducing the overall capacity of the plant. Only products with proven reliability were chosen.
Full technical definition of the project has avoided the need for any 'prime cost' or 'preliminary sums' in the contract price schedules to allow for later definition of requirements. No extensions of time or contract variation orders have been issued.
The plant construction is modular, using pre-fabricated wall and roof panels, with complete electrical and mechanical assemblies ready for immediate installation.
Structural steelwork was manufactured off site, so supporting concrete foundations had to be accurate to within millimetres. Very few local adjustments to the steelwork frames were necessary.
Deep concrete foundations carry the 175 tonne generating sets and withstand the dynamic forces that occur during any possible electrical and mechanical fault, including an electrical short-circuit or faulty synchronisation.
Over 3 200 tonnes of concrete and more than 250 km of steel reinforcing bar were used for the construction of the plant foundations, floor slabs, cable and drainage trenches, and site roads.
The exposed and heavily eroded western slope of the site overlooks the principal entrance to Mombasa port, several refreshment kiosks and informal dwellings. Approximately 4 500 square metres of stone and reinforced concrete revetment have been constructed to stabilise the whole area and prevent further erosion.
Rainwater is ducted through gullies and trenches into the nearby creek. On site oil sludge incineration and sewage treatment facilities ensure all discharges and emissions from the site comply with World Bank Group quality guidelines.
Each main generator has a single exhaust pipe of 1200 mm diameter, terminating 50 metres above ground level. Teams of local steelwork erectors assembled the many sections of pipework, silencers and heat recovery boilers and worked safely at great heights.
Specialist welders assembled two 6 500 tonne capacity main fuel oil tanks, various lubricating oil and water storage tanks and interconnecting pipelines. Each main fuel tank is made up of more than 200 separate plates, up to 14 mm thick.
Duplicate 80 MVA capacity, 11/132 kV step-up power transformers and a twin-bay 132 kV switchyard provide the interconnection between the power plant and the KPLC national transmission system. Telephone, fax and SCADA communications link the power plant with the KPLC national control centre in Nairobi and to the nearby Rabai substation.
Kipevu 2 was the first plant to be constructed and operated under Kenyan environmental legislation. World Bank Group environmental standards were also applied, including those for plant noise, drainage, and exhaust emissions. Predicted exhaust emissions for the plant, meeting World Bank standards, were: NOx, 2300 mg/Nm3; SOx, 140 mg/Nm3; particulates, 75 mg/Nm3. Air quality standards were set after establishing the likely flow of exhaust gas from Kipevu 2, adjacent power plants, and emissions from other industries in the Mombasa area. For the Mombasa area the maximum allowable ground level concentrations of SO2, NO2 and particulates were as follows:
An air quality monitoring station was located at Mazeras, some 15 km west of the site, to monitor compliance with the air quality standards. The station monitors ground levels of sulphur dioxide (SO2), nitrogen oxides (NOx), and particulate matter. The results to date are much better than the minimum requirements.
The commitment to effective environmental and health and safety management extends over the life of the power station. This includes regular monitoring of air quality and site emissions, and the annual reporting of safety and environmental management results to the Kenyan environmental authorities and the World Bank Group.
Health and safety
The health and safety plan applied to all contractors, and cascaded safety procedures and practices down to all managers, supervisors and operators. Its obligations were explained in detail prior to each contractor working on the site, and compliance was strictly enforced. Safety improvement or prohibited work notices were available to correct instances of non-compliance.
Detailed safety regulations applied throughout the site, including excavations, temporary formwork, electrical working, welding, grinding, lifting, and working at heights. The health and safety of employees has been a priority objective and no serious accident has occurred on site throughout the entire construction period.
Blueprint for future projects
Kipevu 2 power plant is the result of careful planning, meticulous design, and a blend of construction and operating expertise from Europe and Africa. It has established the blueprint for other similar projects.