Wind turbines powering a ferry in San Francisco?
This is clearly not an eco-scam, it is just eco-stupid!
Here we have two large vertical axis wind turbines (VAWT) mounted on the roof of a ferry that shoots about the San Francisco Bay, I spied it North of San Francisco from Angel Island today.
So why is it stupid? Well what are the wind turbines for? On yachts and canal-barges and the like it is common to have a small wind turbine on board to trickle charge the batteries when the boat is mored up so you can turn the lights on ow whatever occasionally without having to run the engine. This makes a lot of sense.
This is not what is going on here, this ferry is shooting about the Bay and the turbines were whizzing round charging the batteries. It is a “hybrid ferry” with both diesel engines and electric engines.
The problem with this is that it is a very inefficient way to convert the diesel fuel’s energy into electrical electricity, the drag caused by the VAWTs will always be much greater than any energy they collect while the boat is in motion.
However the boat is not always in motion, it is often sitting in the dock. How much energy do they typically generate when in dock? I suspect not very much - every time I have seen this ferry mored up the turbines are not spinning at all. And, of course, if ti is windy out in the bay then they could be generating more than they consume (in extra diesel).
Electric energy also comes from on board solar PV.
They charge the boat’s batteries from the grid overnight also, I expect that this is where most of their electrical energy comes from.
They estimate they have reduced their fuel consumption by approximately 38%, I doubt this has very much to do with the wind or solar, this energy is coming from the grid and so this ferry is probably more of a diesel/coal hybrid than not a diesel/wind/solar hybrid.
It looks like they are making an new ferry with incorporates a hydrogen fuel cell too (thankfully not the HHO kind!) which should be very interesting and, very much depending on where they get their hydrogen from, actually make an impact on the ferry’s overall emissions, not just its local emissions.
Here is a link to the boat:
http://www.alcatrazcruises.com/website/hybrid.aspx
miciGi:
Not necessarilly.. the drag from the ferry is mostly the the frontal surface area resistance plus the the surface friction along the vehicle of the resultant flow.The front wedge shape directs the orwarairflow up to the superstructure. where it would hump and then follow the surface contours of the upper deck cover causing drag In this instance the force is being generated by the wedge shape of the ship and is mostly flowing upwards.the turbulence at this point breaks up the coherence of the surface flow behind the rotors and reduces drag aft of the highpressure point. directing airflow up and away from the body. have to see it in a wind tunnel to know for sure but it looks ok.sail ships tack against the wind and there are succesful forward movement windprop driven boats. forces in action are not simply wind resistance versus power created.1 hp equates to around 5 amps so any appreciable hp from amps soon ads up to a saving in horsepower used and fuel.fuel cell sounds good. cheers.
10 November 2011, 11:38 pmJon:
Hi there,
11 November 2011, 1:47 amI was kinda agreeing with you about how maybe the turbines cause less drag in the ship by breaking up the air forced upwards by the ship of the bow of the ship. A big maybe. I hae no idea how 1 hp = 5 A though, that is a little like saying that 1 liter = 1 meter, it does not make a lot of sense.
CW Dierkes:
maybe they are efficient with strong crosswind components, but it remains to be researched properly what the real advantages could be.
3 January 2012, 6:14 pm