Energy consumption

In calculating energy needs, the drive motors are excluded here, since these are treated in the section entitled “Drive”. This is based on the strategy of first calculating available energy and then deducting on-board energy requirements, so as to be able to use the remainder, with the addition of stored energy, for the motors.
    Mastervolt, an international supplier of electrical and electronic accessories for yachts, has made available on the web “Mcalc”, an interactive database for estimating electricity requirements for yachts of varying sizes. The largest class of yachts presented there, 49 - 66 feet, is the category most closely approximating the “Eco-Trimaran”. Here a spreadsheet is found which includes all conceivable applications consuming electricity, 79 in total, from engine room sockets and the coffee machine on down to air conditioning. Yet
the motors are not included here, since they are usually powered by diesel fuel. The power rating and average running time (based on experience) is given for each electrical device. The company  mentioned
caters to an international market, while the spreadsheet “Mcalc” is written in English. We may thus assume that it is based on energy consumption habits prevalent in the and the, where energy is used less sparingly than in Germany. In addition, the company’s business interests make it likely that a more generous estimate of energy needs is provided by “Mcalc”. It may, on the other hand, be assumed that the crew of the “Eco-Trimaran” will be inclined to­ward an environmentally conscious use of energy. Thus we remain on the safe side in using “Mcalc” to estimate energy needs.
    We have omitted or rated conservatively in “Mcalc” the larger battery charging devices. Only a smaller, 530 W charger has been included; such a device would be able to be used on the “Eco-Trimaran” to charge
a lead-acid battery for the emergency power supply (in the event that the fuel cells fail). The assumption for the energy consumed by air conditioning and refrigeration has been reduced to one-half, since the cold collected from compressing the hydro­gen gas when filling the storage tank could additionally be used for these purposes. The
heat obtained from decompression 1 when the hydrogen tank is emptied is to be used for heating. Once the storage tanks are full, the hydrogen that continues to be produced can be used directly for heating. The estimate of energy requirements for the bow thruster has also been reduced by one half, since, due its special design involving three movable floats, the “Eco- Trimaran” is expected to require significantly less energy when turning. Energy estimates for equipment serving to stabilise the position of the vessel’s hull in rough seas as well as for equipment to heat diesel fuel have been eliminated entirely. On the other hand, the energy needed to power the bilge pumps has been increased, as three of these are required (i.e. for the three floats). Values given for lighting have been maintained. In this respect, sig­nifi­cant energy savings may be expected in the future as LED technology is further developed, yet presently “energy-saving light
1 Unlike most other gases, hydrogen cools when compressed and becomes warmer with reduced pressure.
bulbs” are still just as efficient. However, the energy needed for lighting amounts to a mere 2.34 kWh per day. No distinction has been made between the northern and southern area of operation in this regard, since the amount of energy saved in the north from air conditioning is conversely required there for heating. Under the conditions described here, an average energy consumption rate of 33.8 kWh per day has been calculated for operating times with a crew, while no distinction is made between travel and mooring periods. The comparable figure for periods without a crew is 0.099 kWh a day, as in this case only bilge pumps, position lights as well as the electronic circuitry for controlling energy production, conversion and storage would need to be powered.

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