Takoradi Power Plant
Takoradi (T3) Power Plant in Ghana
Since 2009 Ghana has faced electricity and gas shortages that have impacted individual consumers, businesses, and the national GDP. The recently commissioned Takoradi T3 thermal combined-cycle power plant not only adds 132 MW to the national grid, but also provides environmental benefits and the flexibility to operate on multiple fuels.
Need for Power and Flexibility
Reliable power generation in developing countries continues to be tenuous yet essential for growth and development as demonstrated by Ghana. In addition to significant electrical load growth due to rapid commercial development, there were also electrical shortages tied to natural gas shortages, as in the case of the Asogli Sunoni plant. This plant relies solely on natural gas and was shut down in 2012 due to ruptured pipelines. Due to intermittent power outages and the resulting load shedding throughout the country, businesses in the manufacturing and mining sectors have been forced to close or buy extra fuel to run their processes. This forced some companies to cut production and increase prices, resulting in negative growth in the manufacturing sector and negatively impacting the Ghanaian GDP.
The Takoradi T3 power plant is a combined-cycle power plant at the Volta River Authority (VRA) power station at Aboadze, near Takoradi. It expands the Takoradi Thermal Power Station capacity by 132 MW or 24%. Takoradi T3, which was designed to operate on LCO or natural gas, is projected to help meet the load growth of the region and provide national grid backup for shortfalls, especially during seasonally low hydroelectric power. The Takoradi T3 project was completed in November 2012 and began producing power almost immediately. It even supplied Ghana with supplemental electricity when the Aboadze Thermal Plant-1 (T1) had a mechanical fault and was shut down for three days in December.
HPI, in partnership with the Canadian government’s Canadian Commercial Corporation (CCC) and its strategic partners, completed the Takoradi T3 power plant. Magellan Aerospace’s Orenda Industrial Power Division was the prime contract for design development and project execution. Orenda contracted HPI Technologies for engineering, procurement, and construction (EPC) of the power plant, along with the balance-of-plant design and plant-wide controls. HPI worked in consortium with S&W Energy Solutions, as EPC engineers and onsite project manager. Orenda leveraged the advantages of the marine-derivative gas turbines from Zorya-Mashproekt in the Ukraine. The Ghana Ministry of Energy, Volta River Authority, is the owner and operator of the plant.
Takoradi T3 was designed to not only increase electrical generation output, but also provide flexibility when shortages in electric power or gas occur. The T3 power plant is rated with a guaranteed net output rating of 127 MW on LCO and 132 MW on natural gas. The gas turbines will operate on LCO until a domestic supply of natural gas is available. The fuel flexibility of Orenda’s Mashproekt GT25000 gas turbines also includes No. 2 diesel, which is brought in by truck for startup and as a backup fuel.
This Takoradi T3 power plant is currently the only thermal plant in the country that has an air-inlet chiller to restore the generation capacity of its machines. The inlet air is cooled by power choking the higher ambient temperature to a steady 15°C, which is the benchmark for ISO performance calculations.
The majority of the control systems are open architecture, commercially off-the-shelf (COTS) PLC controls, which leverage Rockwell Automation’s Allen-Bradley line of controllers known as PlantPAx. This provides better diagnostic abilities and easier troubleshooting and maintenance. The plant’s electric motor starting unit is designed to start and bring the units to full output speed in less than 15 minutes.
Modular Plant Design
Takoradi T3 was a modular design, meaning that the major systems were prefabricated in the USA and Canada. This allowed easier and more rapid onsite assembly and commissioning, which reduced cost and construction lead time while mitigating risks inherent with capital construction projects undertaken in emerging nations. Prior to shipment from the factory, the gas turbines, generators, controls and auxiliaries were load-tested to verify performance and systems integrity. “The T3 plant benefitted from our modular design-build concept which accelerated final assembly and construction at the site. A traditional EPC would have taken at least 12 to 14 months longer,” says Hal Pontez, President of HPI.
Gas Turbine Gen-Set Packages
Orenda provided two 2-on-1 skid-mounted power blocks, each rated for 65 MW and powered by two 25.6 MW Orenda GT25000 gas turbines. Each combined cycle block has two gas turbines exhausting into individual heat recovery steam generators (HRSGs) to drive a 17.2 MW steam turbine generator set. The turbines drive Brush electric generators.
Orenda designed the generator sets on the Ukraine’s Zorya-Mashproekt GT25000 water-injected gas turbines for emissions reduction, but the original marine design also has the added benefit of anti-corrosion materials and coatings. This should improve the durability of the units as they will be exposed to salt air, high rainfall, and high humidity conditions.
Each of the four GT25000 gas turbines is ISO rated at 25,600 kW and 35.5% simple cycle efficiency without losses at 59° F, sea level site conditions, and burning natural gas fuel.
Reducing the Environmental Footprint
Besides the emissions reduction due to water-injection of the gas turbines, Takoradi T3 reduces its environmental footprint by operating on either LCO or natural gas. From an environmental impact point of view, either fuel is attractive—the crude can be burned directly without refinery emissions and the gas would otherwise be flared off or re-injected.
“Ghana expects to begin the production of natural gas this year,” said President John Mahama in February. He said that the gas would initially feed the Aboadze Thermal Plant for power generation and a proposed fertilizer processing plant, before scaling up to commercial production. Natural gas is a source of clean energy for the country and if natural gas production meets a third of the country’s needs it could save approximately $350MM each year. The savings could be used in other areas of the economy. It also means that Ghana could stop using liquid fuels in industry and power generation, reduce emission of greenhouse gases, and opt for value added processing of minerals.
T3X and Beyond
HPI and the Canadian government handed over the Takoradi T3 plant and the commercial operation to the Volta River Authority in March. “The plant’s ability to use light crude oil as well as natural gas means a reduced environmental impact since it will burn gas that would previously have been disposed of through flaring. This also provides the flexibility to still produce power if gas becomes difficult to obtain. Power plants like T3 represent a significant and important trend as developing countries seek a better electrical infrastructure with less environmental impact,” says Hal Pontez, President of HPI.
The Ghanaian government is committed to expanding its program for power production capacity and ensuring security of energy in the country. To this end, HPI and the Canadian government have already prepared the grounds for the construction of another thermal power plant, known as T3 Extension (T3X). When T3X is completed, an additional 132 MW of electricity will be added to the national grid. This could provide some guarantee of sustained electrical power supply and subsequent infrastructure, economic, and commercial improvements for all Ghanaians.