Over the years, board members and executives at Bloom Energy, the VC-funded fuel-cell startup, have spoken of an imminent IPO, imminent profitability and imminently returning phone calls from members of the press.

It looks like that IPO piece might be coming closer to reality.

According to a report in The Wall Street Journal, Bloom has submitted a confidential registration for its IPO with the Securities and Exchange Commission. The report cited "people familiar with the matter." This action by Bloom falls under the Jumpstart Our Business Startups Act, which allows confidential filings for companies with less than $1 billion in revenue.

So, the only news here is that Bloom had less than $1 billion in revenue last year. GTM has already reported that the structure of some 2015 notes suggested that Bloom would have to start the IPO process about this time in order to meet its debt obligations.

The energy company has raised more than $1.2 billion since 2001, has a roster of premier paying customers, and a knack for absorbing state subsidies intended for clean, renewable power. Bloom's investors include the New Zealand Superannuation Fund, KPCB, NEA, Goldman Sachs, DAG, GSV Capital, Apex Venture Partners, Mobius Venture Capital, Madrone Capital and SunBridge Partners.

Board members include: John Doerr of KP, AOL founder Steve Case, and former U.S. Secretary of State Colin Powell. 

The 15-year-old startup claims to have installed more than 200 megawatts of its Bloom boxes in the U.S.

The fuel cell market is growing

Almost 10 percent of Fortune 500 companies use fuel cells for stationary or motive power.

The fuel cell industry grew to $2.2 billion in 2014, up from $1.3 billion in 2013, according to a DOE report, which counts more than 50,000 fuel cells shipping in 2014, for a total of 180 megawatts. More than 81 megawatts of large stationary fuel cells were deployed or ordered in 2014, with Bloom accounting for more than 32 megawatts that year.

Market forecasts are all over the map, however. The research firm MarketsandMarkets sees a $5.2 billion industry by 2019, with a compound annual growth rate of 14.7 percent from 2014 to 2019. According to a 2014 report from Navigant Research, the global revenue for stationary fuel cells will grow from $1.4 billion in 2013 to $40 billion in 2022, while WinterGreen Research sees the stationary fuel-cell market poised to increase to $14.3 billion in 2020.

In the face of these wild guesses, a 2013 study by Lux Research found that in spite of the billions spent on R&D by government and industry, “The dream of a hydrogen economy envisioned for decades by politicians, economists, and environmentalists is no nearer, with hydrogen fuel cells turning a modest $3 billion market of about 5.9 gigawatts in 2030.”  

This is the year

Bloom builds fuel cells of the solid-oxide variety with natural gas as the fuel. There is no heat resource in the Bloom Box as in other CHP fuel cells. The 200-kilowatt units are intended for commercial and industrial applications, and the firm boasts an all-star list of customers, including Adobe, FedEx, Staples, Google, Coca-Cola and Wal-Mart. Bloom has an electricity sales business, Bloom Electrons, which eliminates much of the risk for the customer, as well as a leasing and ownership structure.

On a recent tour of parts of the Bloom fuel cell stack production line, one could not help but be impressed by the sheer engineering heft applied to the mass production and automation of this gnarly manufacturing problem.

Will it be enough?

Bloom's most recent $2.9 billion VC valuation dwarfs the collective market cap of the public fuel cell firms. Can Bloom's Silicon Valley pedigree and ruling-class financiers change the course of the fuel cell industry and make money in this business? Or will the physics and financial reality of fuel cells claim another profitless victim?

For more on Bloom's history, read our reporting on the company's spectacularly negotiated deal with Delaware utility Delmarva Powerthe debatable "greenness" of its fuel cell, and its participation in California's Self-Generation Incentive Program. We've also profiled struggles across the industry as a whole.