Hybrid vessels combine two methods of propulsion, a conventional combustion engine and a rechargeable battery. This reduces fuel consumption and increases operational efficiency, among other benefits. But there’s also a surprising reason why smart forward-thinking shipowners are investing in hybrid vessels – and it might not be the reason you think.
Hybrid vessels can save you money in many different ways now – and they hold a surprising promise to save you even more money in the future. Let’s start with three of the ways in which hybrid ships can start saving you money immediately.
Hybrid vessels save fuel – and therefore money – in a number of different ways. The main ones are:
A) They can operate in fully electric mode, sailing quietly and smokelessly into and out of port. The energy in the ship’s batteries can either come from shoreside charging or from excess power available onboard when the engine is running at optimal load.
B) The battery on a hybrid ship can smooth out the peaks and troughs in power demand, allowing the engine to run at optimal load. This is known as peak shaving. A ship’s engine is at its most effective when it runs at optimal load, increasing fuel efficiency and maximising engine maintenance intervals – two more ways in which hybrid vessels save money.
C) Instead of running multiple engines at suboptimal load, a battery can take the redundancy role of spinning reserve, ready to kick in when needed. This is particularly important for vessels with dynamic positioning needs such as offshore service vessels. The battery has the added benefit of a faster ramp up time and better manoeuvrability.
Without a hybrid system, engine power plants need to be dimensioned for peak load, which can lead to suboptimal loads for the majority of operations. Because a battery can provide an instantaneous boost when needed, the available power can exceed the installed engine power for short periods.
For peak shaving, hybrid systems allow the engine to always run at the optimal point on the specific fuel oil consumption (SFOC) curve, meaning the engine doesn’t have to ‘load hunt’. Removing these dynamic load variations decreases operational costs by reducing maintenance and fuel costs.
Overall, a hybrid ship can provide fuel savings of 15–25% compared to an equivalent diesel-powered vessel. Find out more in seven fascinating hybrid ship trends that everyone needs to know about.
Hybrid ships make it easier to meet increasingly strict emissions requirements, which reduces the risk of penalties such as those of the EU Emissions Trading System (ETS). They do this by reducing the amount of fuel burnt.
All ships over 5,000 gross tonnage that enter EU ports need to comply with EU ETS. To cover your vessel’s emissions you need to buy European Emission Allowances (EUAs), each of which covers one tonne of CO2 emissions per year. If you emit less CO2 than you have EAUs, you can theoretically sell your excess allowance for a profit – or hold onto it for next year. Find out more about how it all works in How to prepare for the EU Emissions Trading System and save money.
Put simply, less carbon-based fuel burnt means less carbon emitted and fewer (increasingly costly) emission allowances needed. But it’s not just about less fuel being burnt – because hybrid ships allow the engine to operate at optimum load, emissions are reduced even further.
With the price of batteries steadily coming down while their performance continues to go up, hybrid is becoming an ever-more attractive option. With batteries on board, hybrid vessel owners can save money by choosing smaller, less costly and less fuel-thirsty engines. The vessel’s energy management system (EMS) takes care of boost and peak shaving.
Hybrid vessels can be designed for peak load operation without compromising the optimisation of the majority of your operations. For example, LNG carriers are designed for a speed of 19.5 knots, but several studies have shown that their average sailing speed today is around 15 knots. This means they are not operating optimally – and therefore they are generating more emissions. Compared to an LNG carrier with a low-pressure 2-stroke solution, a modern hybrid electric system can deliver a:
- 10% reduction in fuel consumption
- 15% reduction in greenhouse gas emissions
- 20%+ reduction in methane slip.
Wärtsilä’s innovative hybrid electric design for LNG carriers has five compact gensets instead of the typical two large 2-stroke engines coupled with twin fixed pitch propellers and four auxiliary engines.
Because this design saves space, the cargo capacity of a standard 174kCBM vessel will increase by 9,000 m3 below deck. The new design also reduces equipment weight by over 40%. This means that even with more cargo, the overall vessel displacement, draft and hull performance will be the same.
More cargo space on board means:
- Higher trading revenues
- Lower unit freight costs
- Reduced emissions per ton
The surprise future promise of hybrid vessels is that alternative fuels will give you even bigger savings!
New fuels such as ammonia and methanol will be essential for the decarbonisation of shipping, but it’s not currently clear which is the right fuel to invest in. Hybrid adds flexibility to your installation – and its benefits will be magnified when alternative fuels come into the mix.
Alternative fuels will cost more than carbon-based options, so a hybrid system that saves you €1 now may save you €5 in future. Whichever fuel you use, you’ll be optimising the amount you burn and reducing your costs.
Handpicked related content: Read more about future fuels in our handy A–Z.
By investing in a hybrid system you’ll save money today in the three ways discussed above – and be secure in the knowledge that your savings could be even greater in future with alternative fuels.
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