The Trybrid design team faces a nasty problem that faces many of us in the drive to deploy the new energy, namely, conventional batteries just cannot hold enough power to store the continuous power stream flowing from the large photovoltaic solar cells. For example, if we were to use say 146 batteries as pictured, which is a lithium, 24 volt 40 amp, best of breed batteries from LifeBatt, weighing in at 16.8kgs each, a total of 2452kg, we could drain all 146 batteries at ‘full stick’ in just 20 minutes. At a retail price of US$1820, or a total of US $265,720, that’s a lot of money and weight to be all spent in 20 minutes!
To be fair, ‘full stick’ is a potentially heavy 415KW, and of course, that is high speed, and beyond the feasible power range of a battery system, even 146 good quality lithium batteries.
With maybe 20kw of solar (and possible wind) power, feeding batteries all day, whilst the boat is idle at anchor, the free solar power available is just going to waste after the batteries are full. Boats spend a lot of time sitting quietly in the full sun, and often also in windy locations, and the energy from the time spent at anchor is way bigger than any power generated whilst the boat is on the go.
So do we just keep adding more batteries, more weight, and more expense, or do we sit back and reconsider the use of these batteries? Should we be just using a battery back as a short term storage method for fluctuating incoming power?
The attractive feature of lithium batteries is, “unlike lead acid, LiFePO4 cells lose little to no energy in discharges of less than 5C.(The C rate of a cell is a comparison of the discharge/recharge current to the overall pack capacity).
So this feature suggests a lithium battery bank would serve the boat better as a temporary holding bank for incoming power, rather than as primary, back up energy store.
It’s this ‘deal stopping’ feature of batteries that is driving the TRYBRID design team to look elsewhere, to storage mediums like hydrogen to put effective use the huge daily stream of energy potentially going to waste from the solar cells. Is hydrogen feasible? The design work will soon work it through….
The implication of a transport platform that can both make and use its own fuel would make TRYBRID rather unusual. There are many transport means using renewable energy, but few if any have the capacity to make and store serious amounts of fuel onboard, in what would be a world first in closed loop energy design, namely, transport that makes and stores practical amount of its own fuel, just sitting in the sun. Buses, cars and trains don’t have the capacity to provide the size of photovoltaic power array to make serious amounts of energy….but TRYBRID by comparison, does it with ease. Interesting.