The potential of batteries on board large ocean going vessels lies in hybridization
Last week we got charged with knowledge on the topic batteries on board ocean-going vessels seen from a two-stroke perspective. The interest in the topic was great, and a lot of people had signed up to join the webinar.
Dr. Susanne Lehner and M.Sc. Philip Holt from MAN gave a presentation, followed by a Q&A session.
The webinar covered where potential lies for battery application on large ocean-going vessels and investigate where there is not. The webinar also addressed some do’s and don’ts in connection to batteries and propulsion. The greatest benefits, according to their studies, are discovered to lie in the benefits of integrating batteries into the electric grid on board.
They presented a case study on the short sea ro-ro shipping, where they had analysed the crossing and power consumption. Some of their findings were presented. In terms of the SFOC curves, the characteristics of a two-stroke and four stroke engines are significantly different and two-stroke peak shaving is not recommended. It was also mentioned that at sea, it will always be more efficient to charge the battery with a two-stroke engine via PTO than by a four-stroke auxiliary engine. This may also be utilized for emission free port stays.
Weight- and volume wise it was concluded that a battery installation for this case, with the current technology level, was feasible. However, cost-wise battery-electric propulsion more than doubles compared to a traditional two-stroke solution. This was also considering the lowest cost scenario and speed reduction. For other purposes than pure propulsion they mentioned that a battery can, through a power take in on the main engine aid the acceleration of the shafting through the barred speed range.
In their presentation, they presented some of the results from the HYCAS study on hybrid power generation. This was a study carried out together with Corvus Energy and DNV GL to explore new cost -effective application of hybrid power generation on larger ocean-going cargo ships. Different scenarios were looked at, one for 2020 and one for 2030.
For the 2020 scenario a genset was replaced with a battery of 500 kWh for dynamic loads, spinning reserve and peak shaving. The battery would require less space and weight, compared to the genset. The result show that the the payback time would be less than two or three years and savings depended on the number of plugged reefers, and that .
For the 2030 scenario four gensets were replaced by a 11 MWh battery and another genset. In this case the battery application was for peak shaving, as well as zero emission mode for port entry/exit. Economically, the benefit and savings highly depend on the fuel prices and battery cost. However, if the fuel cost would be $1000/t and battery cost of $400/kWh the NPV would be positive.
Conclusion from the presentation: The potential of batteries on board large ocean going vessels, with the current available technology, lies in hybridization.
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