When you're playing in and around the cutting edge, expect to get nicked now and again.

But then, the odd setback on the front lines of cleantech innovation should come as no surprise to anyone working in or watching the sector.

Heck, your own friendly Avenger is so forward-leaning, I need special shoes.

Hard knocks are indeed being dealt out these days at schools attended by Verdant Power and LDK Solar.

Dead in the water

For every two steps forward in the marine power sector, there appears to be some unanticipated yet inevitable step back.

Take U.S. tidal energy company Verdant Power. After working hard at a number of marine power prototype devices over nine years, the company was pretty sure it was onto something with its latest design.

This spring, it deployed five test versions of its new large, slow rotating, 16-foot bladed device in New York's East River. A sixth monopile housed instrumentation to monitor fish in the vicinity (see Cleantech.com's Verdant deploys tidal array in New York.)

For a time, the array was producing power. Unfortunately, sources have suggested to Cleantech.com that Verdant's protoypes have all since failed, their blades ripped off by the surging tides.

The company did not return an inquiry this week for confirmation.

Join the Avenger in hoping that Verdant's fifth design is the charm, and doesn't burn down, fall over and sink into the swamp.

LDK roller coaster

Shares of China's high-flying LDK Solar are a shadow of their former selves, losing some 40 percent of their value this week.

Former controller Charley Situ, who was fired "for cause" last month after not showing up for work for a week, was quoted in a report on Wednesday that the company had "poor financial controls and a 250-ton inventory discrepancy," which, if correct, would be a discrepancy equating to an overstatement of about 33 percent.

LDK subsequently formed an internal committee to investigate the allegations, saying it "has found no material discrepancies as compared to LDK's financial statements."

That said, LDK shares fell to $61.55 Wednesday, sunk even lower Thursday and closed at $50.95 today. They'd been trading as high as $71.65 earlier in the week.

Algae whispers

Oh, how we love the biofuel-from-algae sector!

Perhaps inspired by our past musings on the topic (see the Cleantech Avenger's Bowling for GreenFuel, and More slimy goings on in algae), your caped confidante now seems privy to a whole lotta interesting developments.

Take, for instance, word that tiny Aquaflow Bionomic of New Zealand has been entertaining secret visitors from Boeing, intent on investigating the viability of aviation fuel from algae.

Virgin Fuels announced in April it was working with Boeing to demonstrate biofuel in a 747-400. The focus is apparently on testing algae-derived jet fuel, especially its freezing point, according to sources.

Air New Zealand is apparently prepared to make a plane available for testing.

Or take the suggestion, at a Silicon Valley energy conference yesterday, quietly made in the sidelines by Harrison Dillon, CEO of algae company Solazyme, that his firm is now producing algae oil in quantities sufficient to be transported in tanker trucks, not just in test tubes.

While most algae companies are apparently struggling to produce small quantities of algal oil, Solazyme says it's cracked the code.

"We wouldn't have our supply agreement with Imperium Renewables unless we were able to make oil in large quantities," said Dillon sotto voce (see Cleantech.com's Solazyme to supply algae oil to Imperium.)

That's not to say Solazyme's making it cheaply. Dillon said he's been concentrating on volume, trusting that costs would come down over time.

How expensive is it to make algae oil today? One guess puts it at about $1,000/gallon.

Specifically, Boston's beloved-but-beleaguered GreenFuel bought 4,000 pounds of algae last autumn, and then paid another company to convert the algae to ethanol and biodiesel, claims a high level source in the algae industry. Granted, it was an early phase R&D exercise, and relatively small scale, but if you assume a standard nutraceutical price of $100 dollars a kilo, that works out to be about $180,000 of algae.

It’s unlikely GreenFuel received more than 200 gallons of fuel from its 4,000 pounds of algae, so doing the division, that’s $900 a gallon. And that’s without factoring in whatever GreenFuel paid for the conversion, or its overhead.

GreenFuel bought its algae from an Israeli company. Which gave your favorite cleantech superhero pause to wonder why there are no Jewish superheroes given that Stan Lee was originally, in fact, Stanley Liber.

But I digress.

Keep your tips coming!