Demand for distributed energy solutions is high in areas of the world that suffer from power shortages. Rapid, mobile and flexible solutions are the answer, and have proved their worth in areas such as California and Brazil this summer.

The demand for more power – and more power in a hurry – continues in several areas around the world, including California, other sections of the western USA, and Brazil. The trend towards on-site or distributed power is gaining momentum as industrial and commercial users seek reliable and cost-effective sources of energy that can be available within a few weeks, rather than months or years.

Figure 1. By using distributed generation technology, companies in Brazil can reduce their use of grid-generated power while maintaining their commercial activities
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One new solution that has been rolled out (literally) for this energy environment is GE’s ‘Power in a Box’ portable package. With an electrical output of 1 MW, Power in a Box is an integrated, self-contained system usually mounted on a trailer for easy transportation.

“This unit can go from order to delivery, installation and operation in less than 40 days, and can be ready to produce power the day it arrives on a customer site,” said Dan Kabel, general manager of GE Distributed Power, a business unit of GE Power Systems. Since the product was launched earlier this year, several units already have been shipped for projects in the USA and Brazil.

Based on a clean-burning, natural gas engine, Power in a Box comes grid-ready, but can be switched to stand-alone operation in the event of utility power outages or cutbacks. All of the necessary system components including the natural gas engine, alternator, cooling fans, electrical units and auxiliaries are integrated into one standard ISO container that is 40 feet (12 m) long, 8.5 feet (2.6 m) high and 8 feet (2.4 m) long, and weighs approximately 50 000 pounds (22 680 kg). These factors are critical to the mobility and ease of transportation required for this portable unit.

Figure 2. The use of natural gas greatly reduces the engine’s emissions especially when compared to diesel engines, which produce ten to 20 times more pollutants per unit of output
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Power in a Box is the newest addition to GE Distributed Power’s technology portfolio. GE Distributed Power focuses on providing on-site power generation solutions ranging from 7 kW up to 3 MW, for use in residential, commercial and industrial applications. The business is GE Power Systems’ go-to-market enterprise for gas engine gensets, large diesel engine gensets and residential fuel cells, and also leads its emerging technology efforts in areas such as microturbines and larger fuel cells.

Built for speed

“Power in a Box is designed as a robust, reliable solution when on-site power is needed immediately at a business, industrial plant or commercial complex,” said Kabel. “The fully integrated package allows the customer to install the power equipment quickly and easily, without the need to erect a building or devise complex engine systems.”

Gas and electricity connections for Power in a Box are designed to ensure the shortest possible installation and setup times. A closed loop cooling system inside the container eliminates the need for any additional connections. All that is required at the customer site is access to a supply of pipeline-quality natural gas.

“The setup process at the site involves just three steps: levelling of the truck trailer; connection of the gas supply; and connection to the local power grid. Normally, this can be accomplished in less than an hour,” noted Dexter Baptiste, commercial operations manager of GE Distributed Power.

Flexible modules

Typically, Power in a Box would be used as a genset, supplying electricity to the customer and dumping the waste heat in the radiator cooler. With its high electrical and thermal operating efficiencies, the unit also is well suited for combined heat and power (CHP) applications, where the waste heat is used at the customer site. Interfaces for connection to the customer’s hot water system are provided.

Other potential uses of Power in a Box could include landfill and offshore installations. The gas engine can be readily adapted to burn landfill gas, and the containerized concept makes it easier to remove Power in a Box from the old site when landfill gas production slows, and move the unit to a new site. Its compact design also can be adapted for offshore gas and oil production facilities, where space is extremely limited.

Power in a Box is a convertible unit for either 50 or 60 Hz applications. Engine speed can be selected accordingly, to either 1800 r/min or 1500 r/min. The nominal electrical power output is not affected by these two engine speeds. To make this feature possible, special engine tuning has been applied, using a new turbocharging system supported by a boost control system.

Inside the box

The heart of Power in a Box is a spark-ignited, four-stroke, turbocharged, aftercooled gas engine with a high performance ignition system and an electronically controlled air/gas mixture system. The engine is equipped with an advanced lean-burn combustion system.

The use of natural gas, among the cleanest of fossil fuels, greatly reduces the engine’s emissions especially when compared to diesel engines which produce ten to 20 times more pollutants per output produced. A selective catalytic reduction (SCR) system can be added to the Power in a Box package, further reducing emissions by 90 per cent where near zero emissions levels are required.

Figure 3. Power in a Box is designed to be a robust, reliable solution when on-site power is needed immediately at a business, industrial plant or commercial complex
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An engine generator control panel transfers the supply of control power from the starter and control batteries. A Dialogue Network motor management system includes a visualization PC, a central engine and a module control.

The package also includes a self-excited, self-regulated, three-phase generator. It consists of the main generator, built as a rotating field machine; the exciter, built as a rotating armature machine; and a three-phase voltage regulator, powered by a permanent magnet pilot exciter.

An exhaust gas silencer is designed for a residual sound pressure level of 74 dB(A) at a distance of 23 feet (7 m) with one module in operation. The silencer unit is installed inside the container with the noise-treated exhaust discharged vertically into the atmosphere.

“The innovative air intake and outlet system provides both room ventilation and reduces noise pollution,” says Kabel. This system supplies the required combustion air for the gas engine, and also supplies and exhausts the cooling air needed to purge the radiated engine and generator heat. Air is induced through the horizontal air inlet and discharged through the container’s roof.

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At the rear of the container is the cooling system which takes the heat produced by the engine and reduces it via a twin-circuit radiator. The cooling air is drawn directly from the outside ambient air, which enters the cooling system horizontally from both sides of the container and is discharged vertically through fans.

Design challenges

The GE team that designed Power in a Box was confronted with customer requirements for a power package that could easily be transported while requiring minimum storage area and limited setup time.

“These requirements led directly to the main challenge of system design – full integration of all elements of a 1 MW genset into the limited volume of a standard 40-foot (12 m) ISO container,” explained Duncan Watt, engineering manager of GE Distributed Power. Several components were redesigned to fit within the container.

“The team had to design engine cooling and ventilation systems for both 50 and 60 Hz operation, within the same package. This dual requirement was achieved through the use of special software and the development of change-over mechanisms,” Watt said.

Other design features cited by Watt:

  • The Power in a Box module features a direct-connected engine at 1800 r/min, allowing the unit to be converted to 60 Hz power generation without the use of a speed matching gearbox.
  • To meet environmental regulations, all spilled fluid can be contained within the Power in a Box package.
  • Because the high power density of Power in a Box, ventilation of the container is critical. The design team performed a detailed analytical study of airflow and temperatures, using computational fluid dynamics processes.
  • Advanced engine turbochargers were required to allow the power module to operate at higher altitudes and temperatures with no reduction of power output.

First installations

Initial interest in Power in a Box has been particularly strong in areas where the demand for immediate increases in power capacity is the greatest.

“Several Power in a Box packages were installed on sites up and down the US Pacific Coast this summer,” said Kabel. “These systems, along with a variety of stationary, natural gas-powered, 1 MW and 2 MW reciprocating engine systems supplied by GE, added a total of 131 MW of power for the region within a six month period.”

In addition, three Power in a Box systems were recently installed in energy-hungry Brazil. One package went to General Electric do Brasil, a light bulb manufacturer based in Rio de Janeiro, while two units were shipped to GE Varig, an airplane maintenance company at Rio de Janeiro International Airport.

Using this new technology, these two businesses will be able to reduce their use of grid-generated power by up to 40 per cent, meeting the Brazilian government’s request for companies to lower their power demand to help alleviate the country’s energy situation.

“In order to meet the government’s request and keep delivering engines to our customers without disrupting our production, we had to invest in a reliable power system,” said Sergio Barbosa of GE Varig. “GE Distributed Power responded very quickly and was able to fulfill our needs with Power in a Box. We are now able to produce our own power and we are successfully achieving the government’s targets.”

“Our Power in a Box units provided a timely and cost-effective solution, enabling these companies to continue operating at normal production levels,” explained Esteban Obiglio, Brazil and Southern Cone Business Manager for GE Distributed Power.

Obiglio noted that a number of gas companies, independent power producers (IPPs), cogeneration companies and other power producers and energy users across Brazil are looking at distributed generation options such as Power in a Box. “There is widespread interest in the technology throughout the region,” he said.

A world without power

While California is seeing some temporary relief from its long-running power shortage problems, the impacts of the crisis were, in some ways, felt all over the world. While regulators and utilities in California tried to get to the root of the problem, countries embarking on power industry deregulation examined California’s market to make sure they did not make the same mistakes.

California’s power shortages were caused by a variety of factors: at the heart of the problem was an economic boom and a corresponding rise in power consumption, not just in California but in the western USA as a whole. This was exacerbated by a lack of capacity construction during the 1990s, and the fact that California had for many years been able to rely on power imports from neighbouring states to make up for any shortages.

The result was forced rationing in the form of rolling blackouts across many areas of the state and a power industry plunged into financial difficulties due to a poorly-designed, deregulated power market.

Brazil’s problems this year were down to altogether different causes. Around 92 per cent of the country’s installed capacity is in the form of hydropower plants, and two years of low rainfall has left reservoirs at historically low levels. This, combined with strong economic growth, led to enforced power rationing. All consumers were obliged to reduce their electricity consumption by 20 per cent.

The shortages in Brazil will undoubtedly affect the country’s economy and the financial health of many of its utilities. They also highlighted some problems in market structure which had discouraged investment in the power sector. The government is now trying to address these issues; meanwhile many industrial companies are adding their own capacity to overcome shortages.