Field of the invention

The invention relates to an energy management and monitoring method and arrangement in marine vessel.

Background of the invention

In a marine vessel the energy required to generate power to the propulsion unit or to other devices onboard must be stored into the marine vessel. In a seagoing vessel fuel like oil is used as a source of energy and a diesel engine is used as a main engine. In a large marine vessel there may be several diesel engines that rotate generators or main propellers of the vessel. The fuel is delivered to the marine vessel in the harbors or during the voyage by fuel tankers. Other primary source of energy, like liquid natural gas has also been used.

The power production and propulsion system has been adjusted, controlled and monitored continuously to achieve the optimal efficiency. The power control is fundamental part of the control system in order to gain the result of the system. Likewise the propulsion system is controlled to produce the required power using the available electric and/or primary energy. In practice the sufficiency of the energy has not been as critical as the efficiency of the devices and their control systems.

The power control of separate devices gives a good result to consume energy efficiently and economically. This is valid for individual propulsion units, pumping devices, lighting and heating equipments. Further different kind primary energy sources can be used parallel and simultaneously. There may be different kind of fuels available and there may be several diesel engines that are driven parallel or sequentially depending on the required power demand. All this kind of factors and the price of the fuel, the quality of the fuel and the availability of the fuel have affect to the overall energy efficiency of the marine vessel.

Published US patent application US2010/0023239 discloses a power demand management method, which determines the power demand on a power subsystem by optimizing a respective demand-dependent operating characteristic based on one or more operating conditions affecting the power subsystem. Summary of the invention

The target of the present invention is to create a new method for energy management that results in high energy efficiency and takes into account the parameters that are dependent on the primary source of energy or that have a context with overall energy efficiency in the marine vessel. This target is achieved by the features defined in the claim 1 and in the claim 15. Other preferred embodiments are defined in the dependent claims.

According to the invention the method for controlling energy consumption in a marine vessel, which has a plurality of energy consuming users and fuel consuming engines, wherein energy consuming users are divided to at least a first and second user groups each user group having their own energy demands and energy characteristics, the method comprises the steps planning a route for the marine vessel considering one or several items of a plurality: weather forecast, sea currents, sea depths by calculating at least external forces the marine vessel faces on the route, estimating energy consumption for each user group on the route, predicting energy consumption for each user group considering one or several of a second plurality: fuel type, fuel price, emission targets, efficiency of each consumer, and managing an energy balance between the user groups during the route.

The apparatus according to the invention controls energy consumption in a marine vessel, which has a plurality of energy consuming users and fuel consuming engines, wherein the energy consuming users are divided to at least a first and second user groups each user group having their own energy demands and energy characteristics. The apparatus comprises a voyage management tool (2) for planning a route for the marine vessel considering one or several items of a plurality: weather forecast, sea currents, sea depths by calculating at least external forces the marine vessel faces on the route and for estimating energy consumption for each user group on the route, an energy management tool (10) for predicting energy consumption for each user group considering one or several of a second plurality: fuel type, fuel price, emission targets, efficiency of each consumer, and control tool (30) for managing an energy balance between the user groups during the route.

The present invention is based to the idea that different energy consumers have different characteristics in respect of their controllability, in respect of their energy variation and in respect of their power demand and energy demand in different modes of operation of the vessel, for example. The different modes of operations, like drive in harbor, open sea drive or maneuvering drive, have different kind of demands. The present invention utilizes this observation when defining the overall energy consumption and when adjusting the energy balance or energy distribution between the consuming devices.

Basically, the energy consuming devices in the vessel can be divided in two categories. The first one can be called propulsion energy, whose duty is to move and guide the vessel from the port of departure to the port of destination. The second one can be called non- propulsion energy or base load that comprises several energy consuming devices, which are running onboard all the time onboard totally or at least partially independent of the movement of the vessel or the requirements of the propulsion, of the steering or of the maneuvering.

In principle the base load is continuous load and requires certain amount fuel to develop energy and to generate the power to fulfill its demand. However, the base load demand varies continuously, because the environmental circumstances affect to it and because the operation mode of the vessel has effect to the base load. In addition the base load includes energy consuming devices that can be driven in an energy saving mode for short or even longer time period. These loads can be switched off when auxiliary power is required for the propulsion or steering.

The present invention discloses a method for controlling energy consumption in a marine vessel, which has a plurality of energy consuming users and fuel consuming engines, comprises the steps for planning a route for the marine vessel considering one or several items of a plurality: weather forecast, sea currents, by calculating at least the external forces the marine vessel faces on the route, for estimating energy consumption on the route, for predicting energy consumption considering one or several of a second plurality: fuel type, fuel price, emission targets, efficiency of each consumer and for managing an energy balance and/or load shedding on the route.

According a preferred embodiment of the invention the first user group comprises propulsion or steering devices and the second user group comprises non-propulsion devices.

According another preferred embodiment of the invention at least the second user group is able to store energy. The non-propulsion loads may include cooling or ventilation systems that can be driven to the upper limit before the oncoming and predicted growth of energy demand. During the high energy demand the ventilation or other energy consuming devices shall switched off until the allowable limit ahs been reached. By this way it is possible to avoid start additional diesel. According another preferred embodiment of the invention the energy balance is updated continuously during the route. The changing circumstances are taken into account. The measuring data and the history data are utilized when updating the energy balance.

A preferred embodiment further comprises step for forecasting/optimizing startings of the engines. The required energy is produced so that unnecessary starts are avoided. This can be made by switching of unnecessary loads for short periods and storing energy, for example. Further, the energy demand in future is predicted and the second user group is controlled to store energy before power demand increases.

Another preferred embodiment further comprises optimizing operating hours of the engines. Still another preferred embodiment comprises a step for minimizing fuel costs when managing the energy balance.

Still another preferred embodiment comprises a step for displaying and monitoring the energy balance. The personnel can use the updated information when controlling the devices.

In still another preferred embodiment present values of the items are measured and compare to historical data of the corresponding values when predicting and estimating energy consumption.

According another preferred embodiment of the invention the route covers a voyage from the port of departure to the port of destination. This gives overall view of the energy balance and will be updated when changes appear. According another preferred embodiment of the invention the route covers a partial trip having essentially constant circumstances, like operation mode and environmental circumstances According another preferred embodiment of the invention the circumstances of prevailing and coming partial trips are considered.

The Base load or non-propulsion load is optimized so that the energy production onboard is as a whole is economical when combined with the propulsion load needs. Brief description of the figures

The invention will be described in detail with the help of an embodiment of the invention referring to the drawing wherein

- Figure 1 shows a block diagram of an embodiment of the invention,

- Figure 2 shows a graph of power demand of a vessel and - Figure 3 shows a flow chart of the method.

Detailed description of the invention

Figure 1 shows an embodiment of the invention as a block diagram. As it later will be described in more detail the diagram consists of blocks that represent either machine or control devices or data storing and data handling. The arrows from the blocks describe output of the block in question and the arrows to the blocks describe input of the block in question. The input arrow to a particular block transfers either input data outside the arrangement or output data from another block. The output from a particular block transfers either output data outside the arrangement or input data to another block. In the Voyage management tool 2 the basic energy consumption estimate is calculated. Alternatively, the basic energy consumption estimate is calculated in another operational condition optimizing tool. The tool 2 is preferably an external tool, where the voyage route planning is done. The weather and route information 4 are input to the voyage management tool 2. This weather and route information 4 includes e.g. weather forecasts, sea currents and other data that can be prognosticated by a fair probability. The ports data 6 is another input to the voyage management tool 2 and gives available information about the ports of the start point A, of the target point B and of any intermediate port between A and B. The ports data 6 also includes information related to ports in question. The voyage management tool 2 creates a route planning considering the input data and calculates the external forces the marine vessel will face during the complete voyage from point A to point B and on the basis of it the voyage management tool calculates an estimate for energy consumption for the complete voyage from A to B and this output 12 is forwarded as one input to the Energy optimization tool 10. The calculation result of the voyage management tool 2 is forwarded to memory 8 and stored therein.

The estimate for energy consumption 12 from the voyage management tool 2 is utilized in the Energy optimization tool 10 with several other inputs in order to make a prediction of the energy consumption. The input data to the Energy optimization tool 10 includes in this embodiment of the invention Operational mode 14 of the marine vessel, Operating hours 16, Fuel costs 18, Emissions 20 and Efficiency curve 22. The Energy optimization tool 10 may have other inputs depending on the modification of the energy management procedure. Operational mode 14 consists of the data and instructions that define the particulars according which the marine vessel is operating like open sea mode, port mode. The Operating hours 16 define the duration of the different operational mode and their sequences. The Fuel costs 18 gives the fuel types to be used and their availability and the fuel prices. Further the Energy optimization tool 10 has input from the Engine 24, which input consist of the Efficiency curve 22 of the power plant optimization as described later in more detail and the Emissions 20, whereby the emissions of the Engine is input to the Energy optimization tool 10 in order to compare the emissions with the emission target set by the rules or the authorities and limit the amount of the emissions below the target values.

The Power Management System (PMS) 26 of the marine vessel controls the total power production and delivery of the vessel. The PMS 26 may be integrated to the Energy optimization tool 10 as shown in the Figure 1 or it may be realized as a separate unit that communicates with the Energy optimization tool 10. The PMS operation is extended to cover function outputs from to control unit 30, such as power shedding of consumers, function outputs from Power generation/electrical system unit 32, such as propulsion power prediction calculation and customer interface inputs, such as manual starting acceptance of new engine, in order to allow PMS utilize the whole range of input data and calculated predictions of operation in decision making of engine starting and stopping. Control unit 30 is connected to Energy optimization tool 10, to the Engine 24 and to the Power generation/electrical system unit 32. The control unit 30 controls the actual load shedding profiles and load shedding of the system. The control unit 30 also will, based on process references, in an efficient way control the auxiliary consumers connected to the system.

Power generation/electrical system unit 32 generates the required electrical power for the need of the vessel and creates the propulsion power for the propellers. Information from this unit 32 will be transferred to the energy optimization module to get all the basic data from load point to available power in order to find the right energy balance on the system. E.g. the number of generators is decided to produce the required power most efficiently. The Power generation/electrical system unit 32 supplies the energy to the propulsion unit and to the all the electric power consuming devices that are symbolized as Auxiliaries/propulsion unit 34. Some of the devices may are preferably variable speed controlled drives (VSD) which feature is utilized in the energy control as well. The Fuel/fuel quality unit 36 has information of the available fuels and their characteristics in order to find the most efficient way of operation. The unit 36 enables the engine to operate in an efficient way and taking account of the emission targets. The fuel consumption is monitored and displayed by the unit 36.

The arrangement according to the invention also allows user to define consumption reduction buffers, which may be utilized by the Energy management prediction calculation. The propulsion efficiency model and propulsion features and phenomenon that do effect on the system level efficiency are integrated and modeled in the procedure. Based on the prediction, the energy balance management and possible load shedding are reported to the user during the whole voyage. Data generated in the total system are collected into a Data collection unit in a centralized mode to be able to give remote diagnostic and support.

Figure 2 shows an example of the energy efficiency curve to be used in the arrangement according to the invention. A speed/power curve report is generated based on the actual external forces the vessel operates in. This speed/power curve 40 is presented in in the diagram of Figure 2 where power per unit is shown as a function of the vessel of the speed. The actual speed/power value will change several times during a voyage, for example when the vessel change course or come in to shallow waters or the sea-current changes. In the diagram spots are identifying the efficiency point where the vessel has been. Based on the information of the efficiency spot at each moment, the crew of the vessel sees how efficient the operation is on-line. Based on the information, the crew may also take actions to get the vessel operating in a more efficient mode. The closer the vessel is to the line 40, the more efficient is the operation. Generally actions pursuing hydrodynamic optimization move the efficiency spot horizontally in the direction of line 42 and actions pursuing power plant optimization move the efficiency spot vertically in the direction of line 44.

The method according to the invention is described as a flow chart in Figure 3. Accordingly, in block 50 a route for the marine vessel is planned considering one or several items of a plurality: weather forecast, sea currents, and sea depths by calculating at least external forces the marine vessel faces on the route. The energy consumption on the route is estimated in block 52, and the energy consumption is predicted in block 54 considering one or several of a second plurality: fuel type, fuel price, emission targets. In block 56 an energy balance on the route is managed.