Floating Power Plants
Waller Marine has played an important role in the reintroduction of the Floating Power Plant (FPP) since the late 1980’s when the Company was asked to inspect the power barge “Impedance”; a barge constructed with steam generating technology that was first used in the Philippines by the US Army in 1940.
Advantages of the Power Barge
Since that time, Waller has been involved in development, design, construction and opera-tions of numerous power barge projects using all available generating technologies, different fuels and cooling systems
Simple Cycle FPP
220 MW Combined Cycle FPP Installed at site
• Constructed in shipyards under controlled
conditions
• Relatively fast Construction dependent upon
equipment availability
• Can utilize any electrical generating
technologies
•
Transportable power; large capacity can be moved to areas of need quickly•
Fuels can be supplied by ocean transport and stored in adjacent barges•
Financially viable asset for installation in developing countriesHistorical Perspective
Floating Power Plants (FPPs), or Power Barges as they are more commonly called, have been around for many years. In fact one of the earlier units, constructed in 1940 by the US Army Corp of Engineers, a 30 MW steam generation facility and put into service in the Philippines, is still in operation at a site in Ecuador.
Since then, the idea has lain dormant; in fact it was not until the early 1990s when acute power shortages were being experienced in several countries in South America and SE Asia that the concept was revisited. This spurred the construction of several power barges designed with medium and slow speed diesel engines burning heavy fuel oil, with installations in Guatemala, Honduras, the Dominican Republic and the Philippines.
Heavy fuels were selected as the fuel of choice mainly due to cost and availability, with consideration being given to simply meeting World Bank emissions standards being made at the time. Single barge designs ranged from 30 MW up to 100 MW.
In the early 2000s, the capacity of the floating power plant was pushed to a much higher level with the design and construction of a 220 MW combined cycle power barge that was installed in India. This barge used aero-derivative gas turbine technology with heat recovery, inlet air chilling and a steam turbine generator produc-ing a highly efficient plant that initially used naphtha as a fuel.
Floating power barge designs are now charting new territory with projects on the boards with capacities up to 550 MW using technologies that include combined cycle with industrial and aero-derivative gas turbines and Integrated Gasification combined cycle (IGCC) schemes. Greater consideration is also being given to emis-sions and different fuels, particularly as the cost of oil increases to higher levels. LNG, CNG and coal fueled projects are now being considered for installation on FPPs.
Shortly thereafter, designers looked to gas turbine generation for mounting on floating structures and a series of power barges were built using industrial turbines with capability to operate on diesel fuel or natural gas. These units found their initial employment in the Philippines, Bangladesh and Kenya, with maximum single barge output of 105 MW. They have since been moved for service in the Dominican Republic and Ecuador.
Design Considerations
The barge, constrained in its moorings, can thus move vertically with the tides, river levels or storm surges, without any rotational motion. The overall design and construction process are reviewed and surveyed by third party organizations, the international Classification Societies, such as Lloyds Register, the American Bureau of Shipping and others, that not only ensure engineering compliance with Class Rules, but also com-pliance with international protocols concerning pollution and emissions. The completed vessel receives a Clas-sification as a “Power Barge”.
Internals of a 220 MW FPP
100 MW FPP Designed for Orimulsion Fuels
The design of an FPP marries the engineer-ing protocols of the Marine and Power Gen-eration Industries. It operates like a ship at sea only requiring fuel for it’s generating machinery.
The FPP is not designed to sit in waters that are aggravated by waves however, that make it move like a vessel at sea, but rather they are designed for service in protected inland waters such as rivers, lagoons, or ports.
However with modern structural marine engineering and construction capabilities coupled with and under-standing of power generation concepts, the two industry technologies can be fully integrated to perform their intended functions while afloat.
The power barge is the integration of the technical elements of two industries, marine and power gen-eration. While diesel engines have been installed on ships for electrical generation and propulsion since the diesel engine was invented, this is not generally the case for the gas turbine, particularly the indus-trial gas turbine, for which special consideration is needed for hull and foundation loading, stress and vibration.
Conceptual 80 MW CC FPP with Pratt & Whitny FT8 Twin Pak Gas Turbines
Open Ocean Generation
While floating power plants are generally designed for installation in protected waters, solutions to offshore problems have given rise to the idea of open ocean installations. Design of such units is quite different for these facilities since consideration has to be given to vessel motions, deep sea mooring systems, subsea fuel supplies and survival in storm conditions. The generation of high voltage DC electricity and it’s subsea trans-mission is also considered for offshore FPP installations.
Fuels
One of the biggest advantages of the power barge is it’s constructability; the whole power plant can be con-structed under ideal conditions at a shipyard in a location far from the eventual operational site. Much of the system testing is achieved prior to the barge leaving the shipyard. This feature is particularly important for installation of barges in locations where Greenfield construction may be difficult and expensive.
However, by virtue of its very description, the power barge is usually positioned in a coastal location where it can be supplied from various sources by ocean transport, thus providing greater opportunity for lower cost and cleaner burning fuel supply.
The economics of fuels for any power plant, on land or floating, in any part of the world is a matter of availability and cost.
Options are often limited in many coun-tries and thus one has to use available fuels irrespective of cost.
Two 60 HFO FPPs with Fuel Barge - Philippines
Constructability
220 MW Combined Cycle FPP under construction Keel of a 220 MW CC FPP
This permits the import of indigenous fuels such as coal, LNG, orimulsion or condensate, if at lower cost; even crude oil where available as a local energy source may be used prior to re-fining. Suitable floating storage facilities for any fuel can be provided as needed.
Project Implementation
Floating power projects require sound planning and engineering just like any power generation project. Location, site conditions, environmental issues, mooring systems, transmission voltage, cooling sys-tems, permitting, fuel supply and storage, etc are all considered in formulating the design basis and even-tual project implementation.
Two 35 MW Gas Turbine FPPs Operating in Manila on Diesel Fuel
Two 30 MW Frame 6 FPPs Being Readied
The dimensions of the barge are based upon the capacity and type of generating technology to be used but are also based upon the capability to transport and deliver the barge to its operational site. Engineering and construction of FPPs passes through the classification societies review and approval process and their con-struction is continuously inspected by class surveyors.
Transportation
One of the more significant differences of a floating power plant to a land based plant is it’s transportability; being capable of moving the unit from one location to another. This is achieved with the use of submersible heavy lift ships, designed to move very large structures around the world weighing upwards of 60,000 tons.
Ocean Transport of Five FPPs Plus a Fuel Barge
A power barge can be moved from one location to another in a matter of weeks and connected to the grid to alleviate local shortages.
FPP operations are carried out very much the same as land based facilities, with the plant being dispatched in accordance with grid demand. Irrespective of the generating technology installed, the FFP is fitted with an onboard control room complete with data acquisition and all machinery and equipment controls. Switchgear, motor controllers, main breakers and station and step up transformers are all installed on the barge.
Barge Operations
Control Room on an HFO FPP Switchgear on an HFO FPP
Waller Marine, Inc. has designed FPPs using every available generating technology for a worldwide clientele. The Company has also manage the procurement and construction process and taken on complete EPC pro-jects including delivery to site.
