The Price of Power Page 2

As part of my hybrid propulsion research I have been looking carefully at large-capacity litihum-ion batteries as a possible energy source on modern cruising sailboats. Lithium-ion batteries are common in cell phones and laptops, but they are rarely used in higher capacity applications. This may rapidly change, because the hybrid automotive and electric vehicle markets are in desperate need of
Author:
Updated:
Original:
nada_hybrid_drive_system

The ‘Throughput’ Cost

Let’s put all these numbers together, assuming a 100 amp-hour, 12-volt battery.

The lead-acid battery can be cycled through 30 percent of its capacity 1,000 times (this is being generous). At each cycle it delivers 30 amp-hours x 12 volts = 360 watt-hours (Wh). Over 1,000 cycles this is 360,000 Wh, so the lifetime energy throughput is 360 kWh. Looking at a range of battery prices, we find the amortized cost per kWh throughput is between $0.50 and $0.90. This is a “storage” cost over and above the generating cost and the efficiency loss during each cycle.

The TPPL battery gets cycled through 60 percent of its capacity for the same number of cycles (this is probably an underestimation) to deliver 720 kWh. Up front, it will cost up to 50 percent more than a quality conventional battery, but over its lifetime, it will be substantially cheaper (The amortized throughput cost will be less than $0.50 per kWh, based on current pricing) and at all times it will perform better. In particular, its high charge-acceptance rate allows much larger charging devices to be used, which in turn enables any fossil-fueled engine to be more fully loaded which drops the amortized engine cost.

The lithium-ion battery gets cycled through 80 percent of its capacity for 2,000 cycles to deliver 1,920 kWh. It can cost over five times as much as the lead-acid battery and still break even in terms of its lifetime kWh throughput cost. It perfoms much better throughout its life in terms of its charge-acceptance rate, energy-delivery rate, charge/discharge efficiency, and voltage stability. This dramatically reduces the cost of operating the battery and also substantially improves the performance of the DC system in which it is installed.

Arbitrary Assumptions

Clearly, I have made many arbitrary assumptions here. For any given application a fair amount of research would be needed to derive accurate numbers. Nevertheless, in spite of their higher price as compared to conventional lead-acid batteries, the TPPL batteries come out looking good, and the amazing conclusion is that in some circumstances even a $5,000 lithium-ion battery may make sense!

For those who don’t want to spend this kind of money on batteries, but must repeatedly charge them at anchor, aninvestment in solar panels and wind generators can be cost effective. Finally, a small portable generator on deck powering a powerful battery charger is a lot cheaper per kWh of energy produced than running the main engine or a permanently installed generator at anchor. But I usually recommend against this unless particular care is taken to marinize the electrical connection and eliminate the risk of carbon-monoxide poisoning from the exhaust.

Nigel Calder has written many technical articles and books, among them Nigel Calder’s Cruising Handbook, published by International Marine.

Related

GMR19_F53_0539

Boat Review: Beneteau First Yacht 53

Luxury performance-cruising isn’t entirely new. You can go fast and still be comfortable. You can even race if you make the right tradeoffs—or so says Groupe Beneteau, which recently launched its First Yacht 53, in the process also reinventing the company’s “First” brand. ...read more

BirdonBoard

Cruising: Birds of a Feather

One of the neatest things about sailing offshore is the other lifeforms we encounter. We smile when we see flying fish skimming over the surface of the sea. We cheer when dolphins leap and dance in our bow waves. We are duly reverent when mighty whales sound and spout, and ...read more

pirate-marlin-logo

Pirate’s Cove Billfish Tournament

This Spring has felt a bit like a slow day of fishing but it’s almost time to time to Bait…and Switch. The Pirate’s Cove Billfish Tournaments offer something for every member of your crew. Exceptional fishing, fun times with family, old friends and new. Our run is short, our ...read more

Tusk.00_00_16_21.Still001

Tusk by Spyderco

Spyderco's Tusk knife combines a blade and marlinspike to create a multitool perfect for marine use. Made with corrosion resistant materials like titanium and LC200N steel, a nitrogen alloyed steel, and Spyderco-exclusive locking mechanisms, this knife is one of the toughest ...read more

IY11.98_fTaccola©DJI_0200

Italia 11.98 Performance-cruiser

This past winter, SAIL principal editor, Adam Cort, check out the new Italia Yachts’ new 11.98 performance-cruiser at the boot Dusseldorf show in German, and says he can attest to the fact it’s a boat more than worthy of the attention of North American sailors. Available in ...read more

01-LEAD-2017_IDALEWIS_0219

Racing: Doublehanded

I was born in 1955, and although I was a tad young to actually follow the first Observer Single-Handed Transatlantic Race, I grew up in the age of the pioneers of solo offshore sailing—Francis Chichester, Robin Knox-Johnson, Alec Rose, all Knighted for their singlehanded ...read more

newport-400c-updated

Spectra Watermakers

The world's quietest and most energy-efficient watermakers. Our product line ranges from hand operated desalinators that can make 6 gallons a day to our largest system that produces 20,000 gallons of fresh, potable water per day. Spectra Watermakers has the complete package: ...read more

CAPE-COD---Under-sails

Boat Review: Cape Cod

The concept of “daysailer” has grown ever broader over the years. These days the label can be pasted on a boat as small and simple as a Sunfish, as fancy as a 40-footer with a nice big cockpit and plenty of brightwork, or any number of concoctions in between. This Cape Cod ...read more