Annex 2 footnote – Guidance on Calculation and Verification of Effects of Category (C) Innovative Technologies
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Statutory Documents - IMO Publications and Documents - Circulars - Marine Environment Protection Committee - MEPC.1/Circular.896 – 2021 Guidance on Treatment of Innovative Energy Efficiency Technologies for Calculation and Verification of the Attained EEDI and EEXI – (14 December 2021) - Annex – 2021 Guidance on Treatment of Innovative Energy Efficiency Technologies for Calculation and Verification of the Attained EEDI and EEXI - Annex 21 – Guidance on Calculation and Verification of Effects of Category (C) Innovative Technologies

Annex 2 footnote – Guidance on Calculation and Verification of Effects of Category (C) Innovative Technologies

 1 WASTE HEAT RECOVERY SYSTEM FOR GENERATION OF ELECTRICITY (CATEGORY (C-1))

1.1 Summary of innovative energy efficient technology

1.1.1 This chapter provides the guidance on the treatment of high temperature waste heat recovery systems (electric generation type) as innovative energy efficiency technologies related to the reduction of the auxiliary power (concerning PAEeff(i)). Mechanical recovered waste energy directly coupled to shafts need not be measured in this category, since the effect of the technology is directly reflected in the Vref.

1.1.2 Waste heat energy technologies increase the efficiency utilization of the energy generated from fuel combustion in the engine through recovery of the thermal energy of exhaust gas, cooling water, etc. thereby generating electricity.

1.1.3 There are the following two methods of generating electricity by the waste heat energy technologies (electric generation type):

  • .1 (A) method to recover thermal energy by a heat exchanger and to drive the thermal engine which drives an electric generator; and

  • .2 (B) method to drive directly an electric generator using power turbine, etc. Furthermore, there is a waste heat recovery system which combines both of the above methods.

Figure 1 – Schematic illustration of Exhaust Heat Recovery

1.2 Method of calculation

1.2.1 Power reduction due to waste heating recovery system

1.2.1.1 The reduction of power by the waste heat recovery system is calculated by the following equation. For this system, feff is 1.00 in EEDI formula.

  • 𝑃𝐴𝐸𝑒𝑓𝑓 = 𝑃′𝐴𝐸𝑒𝑓𝑓 – 𝑃𝐴𝐸𝑒𝑓𝑓_𝑙𝑜𝑠𝑠 (1)

In the above equation, P'AEeff is power produced by the waste heat recovery system. PAEeff_Loss is the necessary power to drive the waste heat recovery system.

1.2.1.2 PAEeff is the reduction of the ship's total auxiliary power (kW) by the waste heat recovery system under the ship performance condition applied for EEDI calculation. The power generated by the system under this condition and fed into the main switch board is to be taken into account, regardless of its application on board the vessel (except for power consumed by machinery as described in paragraph 1.2.1.4 of this chapter).

1.2.1.3 P'AEeff is defined by the following equation.

  • ( 2)

    where:

    We : Calculated production of electricity by the waste heat recovery system

    ηg : Weighted average generator efficiency

1.2.1.4 PAEeff is determined by the following factors:

  • .1 temperature and mass flow of exhaust gas of the engines, etc.;

  • .2 constitution of the waste heat recovery system; and

  • .3 efficiency and performances of the components of the waste heat recovery system.

1.2.1.5 PAEeff_Loss is the power (kW) for the pump, etc. necessary to drive the waste heat recovery system.

1.3 Method of verification

1.3.1 General

1.3.1.1 Verification of EEDI with innovative energy efficient technologies should be conducted according to the EEDI Survey Guidelines. Additional items concerning innovative energy efficient technologies not contained in EEDI Survey Guidelines are described below.

1.3.2 Preliminary verification at the design stage

1.3.2.1 In addition to paragraph 4.2.2 of EEDI Survey Guidelines, the EEDI Technical File which is to be developed by the shipowner or shipbuilder should include:

  • .1 diagrams, such as a plant diagram, a process flow diagram, or a piping and instrumentation diagram outlining the waste heat recovery system, and its related information such as specifications of the system components;

  • .2 deduction of the saved energy from the auxiliary engine power by the waste heat recovery system; and

  • .3 calculation result of EEDI.

1.3.2.2 In addition to paragraph 4.2.7 of the EEDI Survey Guidelines, additional information that the verifier may request the shipbuilder to provide directly to it includes:

  • .1 exhaust gas data for the main engine at 75% MCR (and/or the auxiliary engine at the measurement condition of SFC) at different ambient air inlet temperatures, e.g. 5°C, 25°C and 35°C; which consist of:

    • .1 exhaust gas mass flow for turbo charger (kg/h);

    • .2 exhaust gas temperatures after turbo charger (C°);

    • .3 exhaust gas bypass mass flow available for power turbine, if any (kg/h);

    • .4 exhaust gas temperature for bypass flow (C°); and

    • .5 exhaust gas pressure for bypass flow (bar).

  • .2 in the case of system using heat exchanger, expected output steam flows and steam temperatures for the exchanger, based on the exhaust gas data from the main engine;

  • .3 estimation process of the heat energy recovered by the waste heat recovery system; and

  • .4 further details of the calculation method of PAEeff defined in paragraph 1.2.1 of this chapter.

1.3.3 Final verification of the attained EEDI at sea trial

1.3.3.1 Deduction of the saved energy from the auxiliary engine power by the waste heat recovery system should be verified by the results of shop tests of the waste heat recovery system's principal components and, where possible, at sea trials.

1.3.3.2 In the case of systems for which shop tests are difficult to be conducted, e.g. in case of the exhaust gas economizer, the performance of the waste heat recovery system should be verified by measuring the amount of the generated steam, its temperature, etc. at the sea trial. In that case, the measured vapour amount, temperature, etc. should be corrected to the value under the exhaust gas condition when they were designed, and at the measurement conditions of SFC of the main/auxiliary engine(s). The exhaust gas condition should be corrected based on the atmospheric temperature in the engine-room (Measurement condition of SFC of main/auxiliary engine(s); i.e. 25°C), etc.

 2 PHOTOVOLTAIC POWER GENERATION SYSTEM (CATEGORY (C-2))

2.1 Summary of innovative energy efficient technology

2.1.1 Photovoltaic (PV) power generation system set on a ship will provide part of the electric power either for propelling the ship or for use inboard. PV power generation system consists of PV modules and other electric equipment. Figure 1 shows a schematic diagram of PV power generation system. The PV module consists of combining solar cells and there are some types of solar cell such as "Crystalline silicon terrestrial photovoltaic" and "Thin-film terrestrial photovoltaic", etc.

Figure 1 – Schematic diagram of photovoltaic power generation system

2.2 Method of calculation

2.2.1 Electric power due to photovoltaic power generation system

2.2.1.1 The auxiliary power reduction due to the PV power generation system can be calculated as follows:

  • feff · PAEeff = {frad × (1 + Ltemp / 100) } × { Pmax × (1 – Lothers / 100) × N /ηGEN } (1)

where feff · PAEeff is the total net electric power (kW) generated by the PV power generation system.

2.2.1.2 Effective coefficient feff is the ratio of average PV power generation in main global shipping routes to the nominal PV power generation specified by the manufacturer. Effective coefficient can be calculated by the following formula using the solar irradiance and air temperature of main global shipping routes:

  • feff = frad × (1 + Ltemp / 100) (2)

2.2.1.3 frad is the ratio of the average solar irradiance on main global shipping route to the nominal solar irradiance specified by the manufacturer. Nominal maximum generating power Pmax is measured under the Standard Test Condition (STC) of IEC standard.footnote STC specified by manufacturer is that: Air Mass (AM) 1.5, the module's temperature is 25°C, and the solar irradiance is 1000 W/m2. The average solar irradiance on main global shipping route is 200 W/m2. Therefore, frad is calculated by the following formula:

  • frad = 200 W/m2 ÷ 1000 W/m2 = 0.2 (3)

2.2.1.4 Ltemp is the correction factor, which is usually in minus, and derived from the temperature of PV modules, and the value is expressed in per cent. The average temperature of the modules is deemed 40°C, based on the average air temperature on main global shipping routes. Therefore, Ltemp is derived from the temperature coefficient ftemp (percent/K) specified by the manufacturer (see IEC standardfootnote) as follows:

  • Ltemp = ftemp × (40°C – 25°C) (4)

2.2.1.5 PAEeff is the generated PV power divided by the weighted average efficiency of the generator(s) under the condition specified by the manufacturer and expressed as follows:

  • PAEeff = Pmax × (1 – Lothers /100) × N /ηGEN, (5)

where ηGEN is the weighted average efficiency of the generator(s).

2.2.1.6 Pmax is the nominal maximum generated PV power generation of a module expressed in kilowatt, specified based on IEC Standards.footnote

2.2.1.7 Lothers is the summation of other losses expressed by percent and includes the losses in a power conditioner, at contact, by electrical resistance, etc. Based on experiences, it is estimated that Lothers is 10% (the loss in the power conditioner: 5% and the sum of other losses: 5%). However, for the loss in the power conditioner, it is practical to apply the value specified based on IEC Standards.footnote

2.2.1.8 N is the numbers of modules used in a PV power generation system.

2.3 Method of verification

2.3.1 General

2.3.1.1 Verification of EEDI with innovative energy efficient technologies is conducted according to EEDI Survey Guidelines. This section provides additional requirements related to innovative technologies.

2.3.2 Preliminary verification at the design stage

2.3.2.1 In addition to paragraph 4.2.2 of EEDI Survey guidelines, the EEDI Technical File which is to be developed by the shipowner or shipbuilder should include:

  • .1 outline of the PV power generation system;

  • .2 power generated by the PV power generation system; and

  • .3 calculated value of EEDI due to the PV power generation system.

2.3.2.2 In addition to paragraph 4.2.7 of the EEDI survey guidelines, additional information that the verifier may request the shipbuilder to provide directly to it includes:

  • .1 detailed calculation process of the auxiliary power reduction by the PV power generation system; and

  • .2 detailed calculation process of the total net electric power (feff · PAEeff) specified in section 2.2 in this guidance.

2.3.3 Final verification of the attained EEDI at sea trial

2.3.3.1 The total net electric power generated by PV power generation system should be confirmed based on the EEDI Technical File. In addition to the confirmation, it should be confirmed whether the configuration of the PV power generation systems on ship is as applied, prior to the final verification.

Parent topic: Annex – 2021 Guidance on Treatment of Innovative Energy Efficiency Technologies for Calculation and Verification of the Attained EEDI and EEXI
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