Kaohsiung Solar Boats: Real boats! Just not solar...

4/4/2012

Coming soon: Cost comparison of lithium batteries vs diesel engines

A New Incarnation of the Love Boat

The "Solar" Electric-powered Love Boat skimming through the Love River

The Kaohsiung Love River has long been a popular tourist attraction. It offers bike paths, beautiful views of the city, and boat rides down the river. The new fleet of 5 solar-powered Love Boats arrived in October 2011 to accompany the existing fleet of 15 aging diesel-powered LoveBoats. At first glance, the new boats' appearance embodies everything that they represent: an immaculate, white body with embedded solar panels in the roof and a simple design that leaves no indication of propulsion turbines or unnecessary gadgets. Each boat's propeller is powered by 2 sets of 12 lithium ion batteries with a capacity of 650 kWh of energy, all contributing to a ride that is utterly silent except for the sound of the boat running through the water.

False Advertising

Many thanks to all the boat captains down on the river,
especially 鄭寶川，損振城，and 曾復強。感謝你們！

The crew was incredibly helpful and happy to speak to me about the ins and outs and technical aspects of the boats themselves. Their candid answers quickly led me to realize that there is a grossly misleading aspect to the advertised name “Solar-powered Boat”. Although there ARE solar panels and they DO feed electricity into the boat’s batteries, they supply a disappointing and nearly irrelevant 4% of the boat’s power. According to the crew, this effectively means that the solar panels power the pretty lights on the side and the propulsion system is almost entirely fed from the land-based power sources charging the batteries.


Solar Failure Break Down
This very disappointing showing by the 18 polycrystalline solar panels rated at 175 watts each is actually not surprising when you do the math. On an average day of full use, draining the 650 kWh batteries to 30% capacity (the recommended level) requires about 455 kWh. The solar panels only supply 20.4 kWh of power in a full day of summer sunlight in sunny Kaohsiung in perfect conditions, or about 4.5% of the total power needed, supporting the crew's estimate of 4% in real conditions.

Food for thought: This 18 panel solar array used on the boats, costing somewhere around $8000 USD, provides nearly enough energy to power the average American household's use of 1000 kWh per month[i]. Seems cheap!

The panels certainly look green. Unfortunately, that's about all they do.

So What Would It Take?
To put it in perspective, powering a boat of this size (and not a speedboat by any stretch of the imagination; more like a large, floating golf cart) strictly by 100% solar power would require at least 325 solar panels. This would cover an area of about 420 square meters, or about twice the size of the average American home. This has actually been done before with the entirely solar PlanetSolar boat, which came with the astronomical price tag of $26 million USD[ii] for a 40-person boat, about the same size as the 36-person Love River boat which cost a measly $250,000 USD each. Despite the exploratory and interesting nature of such a boat, the prohibitive cost of such an experiment makes it exactly that; just a trial with little current practical application.

An underside view of the panels from
within the boat

Although the solar panels are clearly still not a good competitor for diesel when it comes to vehicles, lithium batteries are. The old generation of diesel Love Boats and the new generation of so-called "solar" lithium-powered Love Boats are an excellent basis for comparison of lithium and diesel.

Lithium vs. Diesel

      The lithium ion batteries' shabby  
home underneath the deck

Pulling energy from the grid brings up an entirely new and very interesting comparison: the economic efficiency and polluting potential of electric and diesel vehicles. Electric is purported to be perfectly clean and extremely cheap, which it basically is… at the exhaust pipe and at the gas pump. But what about the pollution created at local power plants to produce the energy needed to charge the batteries? How does the cost of diesel compare to those electricity bills? How expensive are EV’s compared to traditional vehicles? Let's take a look.

One of the Love Boats settled for the night,

happily guzzling from the grid

The batteries may not be pretty, but
they're definitely cooler than the
diesel engine!

Carbon Footprint Comparison

A common point of contention is the assumed cleanliness of the electric vehicle. Although EVs were a luxury toy at best in the past, they are now a transportation alternative coming ever closer to the mainstream as new releases like the Nissan Leaf arrive on the market. The solar-powered Love Boats’ 96% battery-drawn energy places it squarely in electric vehicle territory. This means that it is taking energy from the local power grid, aka a mix of power plants including coal, natural gas, and wind among others[iii][iv][v].

The US’s energy source distribution

produces 612g of CO² per kWh 

Taiwan’s energy source distribution

produces 498g of CO² per kWh

The worldwide energy distribution

produces 622g of CO² per kWh

Is the Grid Cleaner Than Diesel?
Compared to diesel, which produces an average of 821g of CO² per kWh[vi], it is significantly cleaner to feed your vehicles off the grid everywhere, but especially in Taiwan. This disparity can mainly be attributed to the increased use of nuclear and hydroelectric power. Although these energy sources are generally categorized as “clean” energy, it is worth remembering that they create other problems such as the disaster in Fukushima for nuclear and local wildlife pattern disruption and water supply tainting for hydro[vii], calling into question their viability as sustainable technology.

In the case of the Love River Boats, the diesel power produced is again much dirtier. Each trip on the river takes 3-4%* of the battery-powered boats’ 650 kWh battery charge*, or about 22 kWh, while a trip in the diesel boat uses about 3 liters of fuel*. One liter of diesel produces about about 10 kWh of energy[viii], so one trip requires about 30 kWh. This translates into the battery-driven boat producing 11,347g of CO² to the diesel driven boat’s 24,630g of CO² per trip, making charging off the grid more than twice as clean as diesel. Also consider that the battery-powered boats are larger, and a similarly sized diesel boat would produce even more CO².

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[i] - http://205.254.135.24/electricity/sales_revenue_price/xls/table5_a.xls
[ii] - http://www.polaroid-eyewearstore.com/news/29/CNN%3A-Solar-boat-promotes-path-to-cleaner-fuel.html
[iii] http://www.power-technology.com/projects/hsinta/

[iv] http://www.eia.gov/energy_in_brief/major_energy_sources_and_users.cfm

[v] http://en.wikipedia.org/wiki/World_energy_consumption#Primary_energy

[vi] http://www.stewartmarion.com/carbon-footprint/html/carbon-footprint-kilowatt-hour.html#carbon-dioxide-from-one-kilowatt-hour
[vii] 

[viii] http://ies.jrc.ec.europa.eu/uploads/media/TTW_Report_010307.pdf