Posted on 07 August 2019

Optimizing of Power Sources for Use with Fuel Cell Technology

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With energy demands ever increasing, fossil fuels being depleted and concerns about climate change continuing to rise, the ways in which modern society is being powered are now under close scrutiny. International legislation is being passed to curb carbon emissions and greater emphasis is being put on the utilisation of renewable energy resources. Driven by such circumstances, the global market for hydrogen fuel cells is expected to witness a compound annual growth rate of more than 15% between now and 2017 (according to RNCOS).

By Rob Hill, Director of Sales & Marketing, Powerstax

These ambitious projections will only become a reality, however, if proliferation of fuel cell technology starts to gain more momentum in a broader cross section of everyday applications and the supporting hardware utilised has the ability to make fuel cell powered systems as cost-effective, energy efficient and easy to implement as possible.

Shipping is one of the areas where the use of fuel cells could have a major impact, as this currently represents nearly 10% of the UK’s total carbon emissions. So far relatively little traction has been made here, but developments down in the West Country might help to change all that. Keen to move to cleaner energy, Bristol City Council has recently funded a £225,000 project that provides the city’s inhabitants with the UK’s first ever fuel cell powered ferry service. The project is part of the council’s Green Capital initiative.

The 36 foot long, steel hulled ferry Hydrogenesis, which has a two man crew, traverses Bristol Harbour. It can carry up to twelve passengers and has a maximum speed of 10 knots. While diesel powered craft have a heavy impact on the environment through air and water pollution, the electro-chemical process employed this vessel produces no harmful by products. As fuel cell implementations have no moving parts, their working lifespans are much longer than diesel engines. In addition, they offer far less noisy operation. Bristol-based Auriga Energy was given the task of designing and developing the fuel cell system that would power the Hydrogenesis. Established in 2007, the company specialises in creating of highly efficient carbon free energy solutions by employing the latest innovations in fuel cell technology. It relies on the talents a small, highly experienced team of engineers who previously plied their trade in the avionics and defence industries (working for the likes of Marconi, BAE Systems and Thales). This team takes fuel cell stacks then develops highly sophisticated, application specific systems (consisting of both hardware and software) around them that will deliver maximum operational performance.

“It was decided that ferries would be a good starting point,” says Jas Singh, Managing Director of Auriga Energy. “This could show Auriga’s technology in action and prove that fuel cell operation can be commercial viable as well as deriving ecological benefits.” “Though the initial implementation outlay is quite high, once this is dealt with operational costs being highly competitive” he continues “If you look at the whole of life costs, then moving to fuel cells becomes more favourable, even before you take into account their green credentials.” Bristol, through the work of Brunel, can boast a long and eventful history when it comes to maritime innovation. It is perhaps apt then that where the Hydrogenesis is moored lies almost in the shadow of Brunel’s ocean liner the SS Great Britain.

Jas Singh of Auriga Energy, next to Brunel’s SS Great Britain

“Every element of the power system needs to be working at the highest possible levels of operational efficiency,” Singh explains. “This means that the amount of hydrogen that the ferry uses each day can be kept to a minimum to lower the running costs, thereby making the project even more economical.” The system, which is deployed in the ferry’s stern, consists of four fuel cells delivering up to 12kW to power the ferry. The fuel cells are supplied with hydrogen from a 350Bar tank. Two DC-DC modules are needed; the first is at 24V and looks after the control system; the second is at 12V and sees to the supplemental electricity needs (such as the boats lighting system, etc.).

The DC-DC converter modules have a key role to play in the success of this application and so the specifying process needed to be given a great deal of consideration. These modules have to take care of regulating the voltage output.

It was essential that they possessed a very wide voltage range, in order to cope with the variation of the fuel cell output. In addition, high levels of efficiency and compact dimensions were both very important factors.

“I had previously used Powerstax modules in our fuel cell powered fork lift development and the performance levels they achieved were highly favourable. As a result when it came to specifying power modules for the ferry project, it products seemed like the best choice,” states Singh. “In addition the technical support that the Powerstax team were able to offer and their ability to make adjustments to the product proved will be invaluable in the future.”

Based on its industry-proven brick technology and strong power engineering expertise, Powerstax has introduced a series of high performance DC-DC converter modules that are targeted specifically at serving the rapidly growing fuel cell market. These high density modules in this series can provide engineering teams looking to implement fuel cell based power systems with a highly optimised off-theshelf solution, rather than having to look into expensive custom designs. They accept 40V to 120V input direct from many popular fuel cells models and deliver a stabilised output of up to 500W. Power efficiency levels reach 91%. The modules in Powerstax FC series are offered in an industry standard full brick (11.68cm x 6.10cm x 1.27cm) format, with power densities of up to 5.53W/cm3.- so that system performance can be maximised while taking up minimal space.

The Hydrogenesis - the UK’s first fuel cell powered ferry

To increase flexibility, the FC series is available with output voltages of 12VDC, 24VDC, 28VDC and 48VDC. Over-voltage, under-voltage and short-circuit protection mechanisms have been integrated into each module. In addition, a proprietary monitoring feature safeguards against system failure conditions arising. Active load sharing means that the output from an array of multiple modules can be maximised. The FC series has an operational temperature range of -20°C to +100°C, with a MTBF value of 1.1 million hours assuring continued system reliability.

Schematic of the power system used in the Hydrogenesis

The highly reliability power systems offered by Powerstax are very well suited to performance-demanding applications. The company has off-the-shelf solutions like the FC series, as well as full custom, intelligent power solutions tailored for individual customer needs.

The implementation of an environmentally-friendly ferry via a highly integrated hydrogen fuel cell-based power solution will be the catalyst that helps to eventually make Bristol Harbour a low emission zone. Auriga is now in discussions concerning further nautical applications - on the Norfolk Broads and in Venice. The company is also talking to a major UK-based ferry operator about the possibility a larger project being undertaken in the future.


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