Manufacturers of hybrid-electric gensets are stressing the emissions-reducing capabilities of their equipment, coupled with its ability to improve fuel consumption
In a high-powered partnership, Kohler and US defence contractor Leonardo DRS are combining resources to develop hybrid-electric gensets under an initiative dubbed Total Onboard Power Solutions (TOPS) that promises to speed up battery-powered propulsion. Simultaneously, Fischer Panda is also jumping on the green bandwagon with a new range of variable-speed, direct-current generators designed for electric propulsion.
As far as Kohler and Leonardo are concerned, everything is on the table – AC and DC variable-speed systems, emergency generators, diesel-electric hybrid and zero-emission propulsion modalities, whatever is needed. Targeting commercial vessels and mega-yachts, they see themselves as integrators that pull together any relevant technology.
“The TOPS team will work with ship developers to identify individual power needs for each project and propose a conceptual design for the specified requirements, using readily available products from their combined portfolio,” explains Clive Wilgress-Pipe, director of business development and strategic programmes at Leonardo DRS in a press release.
Meanwhile, Fischer Panda may be a step or two ahead with its new VS Series. The breakthrough in these gensets is that they enable the speed of the generator to be regulated according to how much power is required. The engine’s rpm can be adjusted to meet the power demand of the propeller. The system also cuts noise and fuel consumption, Fischer Panda claims. The biggest of the range boasts a power output of 100 kw, enough to enable silent electric cruising under batteries alone or hybrid cruising under batteries and generator, the latter functioning as a range extender.
The great advantage of variable-speed generators, says sales and marketing director Chris Fower, is that they adjust to the fluctuating use of power, unlike conventional engines which are mechanically connected to the propellers so that the rpm of the engine and propeller are fixed. “[Fixed systems] reduce engine life, increase noise and [result in] inefficient fuel consumption,” he says.
A new oversight system, FP Control, monitors the generators as well as the connected drive system and batteries. Nothing if not comprehensive, FP Control pumps out information on how much power is being drawn, how much is going back into the battery, and how efficiently the electric drive system is functioning.
At the smaller end of the market, the Volvo D2 engine-driven Polar Power’s 8340VP-40 four-cylinder DC generator delivers 13-20 kw, enough for big cruising yachts and small commercial vessels relying on hybrid-electric propulsion. According to Polar Power, for auxiliary power the DC generator can be used with a central battery bank and an inverter so that DC and AC power can be provided day and night. “[The generator] is engineered for large cruising yachts and commercial vessels with heavy electrical loads,” the company claims. “Properly configured, the generator outperforms a convention 40 kw AC generator in every aspect.”
The 8340VP was designed around electric propulsion. “The concept is to place one or two DC generators in the most optimum location within the vessel to provide power for the electric propulsion motors and DC to AC inverters, and to charge the batteries, all at the same time,” Polar Power explains. And although it won’t work on cruise ships, one of the benefits of a central battery bank is that the vessel can get under way immediately under electric propulsion without having to warm up the diesel.
The Volvo engine plays a big role in Polar Power’s generator. A Penta D2 that has been developed from the tried and trusted Perkins 404D-15, it is a four-cylinder unit that typically runs more smoothly than engines with three or fewer cylinders. Cooling is by fresh water, reducing the risk of internal corrosion.
Meantime Kohler has been refining its latest range of Scania-powered 350 kw-500 kw gensets in other ways than for electric-hybrid use. They feature a clever technology called double-bearing alternators that, the company says, makes the systems more reliable during hard duty or heavy weather. “The double-bearing design reduces stress on the engine flywheel housing [which] results from the G-forces when the vessel passes through rough seas,” a release explains. It is all part of reducing the loads and extending the genset’s life. A bespoke software system includes an option for managing the load, extending the time between maintenance.
Meantime the leading genset manufacturer, Cummins, continues to dominate what might be called the Big Bertha market. The largest distributor globally of marine generators, the US manufacturer’s latest turbo-charged diesel generator, the K19-CP, produces a whopping 335-460 w from an inline, six-cylinder engine. It also comes in heat exchanger or keel-cooled configurations. According to Cummins’ technical literature, the single-bearing, close-coupled permanent magnet generator provides constant excitation under all conditions.
But this is not Cummins’ biggest marine generator. Suitable for cargo ships and other big vessels, the 12-cylinder K38-CP is another turbo-charged, diesel-fuelled heavyweight that tips the scales at 18,000 pounds (8,165 kg) and puts out 764-920 kw. Unsurprisingly, Cummins describes this generator as “engineered for the tough demands of the marine environment with superior durability and higher uptime requirements.”
Bigger and more powerful again, Cummins K50-CP delivers an awe-inspiring 1050-1240 kw of energy, quite enough to power a giant of the oceans. Its technical features include a six-wire, three-phase alternator with plenty of reconnectable outputs, availability in heat-exchanger or keel-cooled configurations, as would be expected. This model weighs at 21,000 pounds (9,525 kg).
Unusual among genset makers, Cummins designs and manufactures all the major components including engine, alternator and all-important control systems. According to Cummins, this makes for “complete system harmony”.
It is not all about brute force though. Cummins’ latest generators are being steadily refined to make them more user-friendly onboard. The current versions are easier to install because they have fewer complex mechanical connections. In a peace-of-mind solution, they also come with multi-station alarm and monitoring panels that run through a local digital network.
Cummins’ latest generators reflect what the company calls its Planet 2050 strategy that calls among other goals for greenhouse gas emissions from newly sold products to be slashed by a quarter as early as 2030. As the executive director for worldwide environmental strategy and compliance, Brian Mormino, explains: “Our vision for 2050 is a world where Cummins power the world’s really important work with carbon-neutral products and operations.”
Progress also continues apace in the lower-powered segment of the market. Florida-based MasPower’s Yanmar-powered low-rpm, 13-22.5 kw model is an all-American product that comes with a range of useful options such as a four-gauge remote instrument panel, auto-start functionality, plug-in wiring harnesses, and a siphon break. A smooth-running generator, the system operates at 120 or 240 volts.
Like all of the current crop of marine generators on the market, MasPower’s units do more with less.