Turning waste heat into electricity on board passenger ships – Industrial Heat Power
TEXT: BRUNO JONATHAN
While safety is still the paramount concern in the maritime transport industry, environmental protection has emerged as the other main focus. At a time when many governments and NGOs are willing to help funding innovations in shipping, all avenues are explored in an effort to improve efficiency in respect to lessening environmental impacts and improving operational economy. One such initiative, with tangible commercial potentials, is the recent development in heat-recover technology.
More specifically, in the passenger shipping sector, this innovation concerns the applicable technology of generating electricity from waste heat. Only a few years ago, it was difficult, if not impossible, to conceive the viability of such an approach on account of costs. Recent improvements in efficiency, designs and production process are showing encouraging results, making its implementation economically viable without relying on grants and subsidies.
HOT WATER ELECTRICITY
Recovering and reusing lost heat is not a new concept in shipping. There are two main sources of waste heat on board a vessel. The first one is the high temperature heat generated by exhaust gases (approximately 350°C). This heat is generally used to heat water in boilers and turn it into steam. On board smaller ships, such as ferries and cruise vessels, the steam produced is often used to heat fuel and oil for instance. On bigger vessels, such as VLCCs, the amount of heat recovered from exhaust gases can be enough to produce electricity through a steam turbine. Technically, steam turbines could also be installed on large ferries and cruise ships. The major problem associated with operating steam turbines and larger Organic Rankine Cycle (ORC) solutions (essentially reversed refrigeration systems) is that they cause drops in power output because of the variations in engine loads. These systems operate best on constant speed conditions. The second source is the heat from the water used to cool the engines. This heat is commonly used to boil seawater in the process of producing fresh water. Because of the relative low temperatures, around 70-90°C, there are only rare examples of this heat being used to generate electricity. “A few years ago,” a newbuilding project manager told us, “it was not economically viable to consider it for ferry newbuildings, the cost of a device for turning the engine’s heat into electricity was way over EUR 1 million, for a relatively low output of electricity produced.” Ashore, such practices are already widely adopted in industries that produce a lot of waste heat. Because of the relatively smaller size of the marine engines, harnessing energy from this heat source is not yet commonly seen on board passenger ships. An ORC system is generally installed on those vessels to take advantage of this heat source. The process involves putting a fluid under pressure using a pump (as illustrated on the adjacent schema); it is then heated by the 70-90°C engine jacket cooling water, which vaporizes the fluid into gas that powers the turbine to generate electricity via a generator connected to the switchboard. Conceptually this is an ideal innovative technology for passenger shipping, as it reduces energy waste, increases efficiency and lessens environmental impacts.
THE VIKING FORERUNNER
Viking Line’s last newbuild, VIKING GRACE, a floating laboratory for new technologies, is a good example of what could become an industry standard in the next few years. It is not about featuring a technology that can save one or two per cent of fuel a year. The aim is to develop technologies that, together, can achieve double-digit percentage savings. Built in 2013, VIKING GRACE was the first large-scale LNG-powered passenger ship. In 2015, partially funded by European Union subsidies, a heat-recovery system was installed on board the vessel by Climeon, a Swedish company. This 3mx2m device can produce 120kW of electricity. “We have been looking at different organic rankine cycles and the efficiencies of those equipment have been very low (approximately 50% lower),” said Kari Granberg, Manager NB Project & Technical Development at Viking Line, in a press release statement issued in August 2017. “With the Climeon Heat Power system we can save money and at the same time clearly decrease our carbon footprint. We have now decided to include the Climeon Heat Power system, as we develop new vessels (i.e. the ship being built at Xiamen Shipyard, China) and are evaluating the possibility of rebuilding our existing vessels so that the technology can be used throughout our existing fleet.” Climeon has been making steady progresses in developing its heat-recovery system and its product is gaining popularity. “Since the implementation on board the VIKING GRACE, which was our first maritime project, we have made great progress,” said Carl Berglund, Head of Maritime Sales at Climeon. “The capacity of each Heat Power module is now 150kW with an even smaller footprint of 2mx2m. For Viking Line’s next vessel, we will provide a solution with a nine-time higher power output compared to the pilot installation on VIKING GRACE. This is a great indication of how satisfied Viking Line is with the pilot installation. In addition to Viking Line, we have also received an order from Maersk for a pilot installation and from Richard Branson’s Virgin Voyages to deliver a 900kW system for each of their three cruise ships being built by Fincantieri.”
DEVELOPING BEST SOLUTION
Apart from Climeon, a few other companies, including Mitsubishi and Enogia, are also developing this technology. Enogia was founded in 2009 to design ‘low grade’ heat-recovery systems for shore side applications. Recently, the company entered the shipping industry by designing a system for a fishing vessel operating from Ancona, Italy. The project, known as Efficientship, was funded by the EU under the LIFE+ programme. In the summer 2017, this fishing boat became the first vessel to have a small (sub-100kW) ORC installed. The unit, recovering heat from the exhaust of a 400hp class engine, is undergoing sea trials. The results are expected in mid2018. In collaboration with three UKbased companies – AVID Technology, RED Engineering, and Royston Marine – Enogia is also engineering and building a 2mx2mx2m system, with an expected 200kW power output. AVID, a leading automotive technology company, is responsible for delivering the project, as well as the provision of a bespoke generator and electrical drive combination. The aim is to carry out a cost optimisation exercise in order to ensure that there is a commercial potential for this product without the need for government subsidy. “Bringing automotive expertise into the marine industry has the potential to make this a disruptive technology,” said Vahid Walker, Project Manager at AVID. It does appear that this as yet experimental technology is a product of cooperation with a government backing. “The first 200kW maritime system we are building is part of a GBP 3.6 million project, financed by the Energy Technologies Institute (ETI), a public-private partnership between global energy and engineering companies and the UK Government,” said Arthur Leroux, CEO of Enogia. “On our side we designed the cycle and the turbine, chose the components for the whole system, assembled them, and we will soon test and integrate it.” The project aims to deliver a cost-effective waste heat-recovery system for all kinds of ships. The initial system will be installed on board a yet unnamed merchant vessel. The device is designed in accordance with DNV GL rules. It will require very low maintenance by the crew besides cleaning the seawater exchanging. “We don’t know yet which ship will be equipped, but we expect it to be done by the end of the year,” said Leroux. “We’ve conducted feasibility studies for containerships, tankers, and ferries, etc. Concerning the ferries, we’ve studied the suitability of a 5,000-gross-ton dayferry, powered by two engines with a total output of 8MW. We’ve come to the conclusion that when running, the two engines would bring enough heat to our device to consistently produce 200kW of electricity.” There is unique challenge when implementing this technology on a ferry. “The only difficulty you have when talking about a ferry is the space availability in the engine room, which is often very compact,” said Sylvain Pascal, Engineer and Manager of the Maritime Department of Enogia. “In the case of a retrofitting, one would need to install the system piece by piece wherever room can be found. In the case of a cargo ship (containership, VLCC, etc.) or a passenger ship designed with available space for our device, it would be much easier because our standard 2mx2mx2m module could be installed very easily.” “Once the test phase is over, and adjustments made, we will supply this solution at a very competitive cost and footprint to power ratio. With the current oil price, it will take shipowners less than three years to [achieve a satisfactory] return on investment, making it the most competitive solution in this market,” concluded Arthur Leroux. Heat-recovery technology is thus an integral part of sustainable passenger shipping business of the future.