Introduction

A captive power plant is a plant that supplies power wholly or primarily to one industrial customer (or a limited number of industrial customers), rather than to a utility. In many countries the term “captive” is used interchangeably with “embedded” generation. However, this is not always the case. In Nigeria, for example, captive power plants are those where output is consumed by the owner of the power plant whereas an embedded generation plant is one where the owner sells the power generated to third party customers.

They are a form of distributed generation, generating power close to the source of use. Distributed generation facilitates  high fuel efficiency along with minimising losses associated with the transmission of electricity from centralised power plants.

JINAN gas and diesel engines make ideal captive power plants where there is a localised supply of fuel. This might be from a gas pipeline, but can also be transported via vehicle as compressed natural gas (CNG) or liquefied natural gas (LNG in the case of the gas generators). Green power Utility has sold over 100 gas and diesel engines here in Nigeria for captive uses.

Gas-fueled captive power plants are most fuel efficient when used in a combined heat and power (CHP) configuration. Here a facility can generate not only electricity, but also the heat generated while running the generator.

Benefits of Captive Power plants

Many industrial users, such as mines, steel mills, refineries, fertiliser plants, etc. have significant power requirements and in developing economies, the national utilities often do not have the capacity to supply power on a stable and reliable basis. Indeed, in countries facing power shortages, it is often the more intensive industrial users that are not supplied during periods of load-shedding.

Commercial reasons for developing a captive power plant generally centre on a need for a high level of control over the development, construction and operation of the power plant, where these needs cannot be met reliably from the grid, either because new generation capacity is needed anyway or because of doubts about the physical condition or management of the existing system. A captive power plant provides these customers with security of power supply, coupled with greater control of increases and decreases in generating capacity, to align with their production cycles.

Technical reasons for developing a captive power plant can also include the offtaker’s need for other products that can be provided by a cogeneration plant, and a remote site location where a grid connection is not feasible.

For example, cogeneration plants can provide heat to the offtaker in the form of steam, which is required by petrochemical refineries and paper mills. Plants can also be configured to provide other products, such as water desalination to a dedicated offtaker. Another example is a captive power project supplying a bottling plant, where the carbon dioxide produced by the power plant was purified to food grade and then used to produce sparkling drinks that were then bottled by the plant.