It's both less efficient and more expensive than burning natural gas in a turbine.
Its data sheet claims 52% efficiency [1], while current generation CCGTs are 60% efficient (e.g. [2]).
Its commercial price is $7,000-$8,000/kW(e) [3]. This is ten times the cost of CCGT power plants, at ~$700-800/kWe (e.g. [4,5]). (This does NOT mean the amortized cents/kWh cost is 10x higher -- most of the final cost is the gas fuel). Ref [5] is particularly relevant, it's financial estimates from California's state energy commission.
edited to add: According to the link [6] in the OP article, the commercial price of the Bloom Box already includes state rebates, and the real cost is twice as high ($14,000-$16,000/kWe). It also reports comparable costs for competing fuel cells ($11,200/kWe for ClearEdge, and $30,000/kWe for Panasonic's really tiny fuel cell).
"A 100-kilowatt Bloom server array costs around $700,000 to $800,000, or $7,500 a kilowatt, after incentives that cover around 50 percent of the costs."
I'm pretty skeptical about Bloom Energy, but it's not fair to compare the efficiency of a 375 MW gas turbine against a 100 kW fuel cell (assuming that customers care about local generation and aren't just looking for the cheapest power). Maybe you should compare against a microturbine.
It's all a very successfully executed PR stunt. Local generation only matters in places where electricity distribution is unreliable or nonexistent (such as shopping malls in India having diesel generators on site).
For starters, you have to pay for the distribution of the energy from a massive gas turbine, including maintenance salaries, capital investment in the energy network, marketing, insurance of all of the above, interest on capital expenditure to build the turbine, etc etc etc. A Bloom Box's energy is consumed immediately where it is generated.
Yeah I think this is more of a PR stunt than anything else. The technology has potential but at the current moment, but it isnt superior than what is out there. Biomass is green but there isnt enough of it available for cheap. So I think Bloom boxes will have to use natural gas (which isnt green) to scale.
