Roger, you're far more trusting in the fossil fuel industry than I, and frankly I don't understand it. The most lucrative industry in the world has accomplished far more at advancing the art of fraud over the last 140 years than anything related to providing power, and nearly all of it has been detrimental to the environment.

"Would you have us believe that the operators of the Delta plant would contract for delivery of X million BTUs of hydrogen gas daily, pay the contracted supplier for it, and then not use it?"

Of course not, that would cost the operators money. They might, however, contract for delivery of .5X million BTUs of hydrogen, and send out a press release claiming that due to advances in efficiency, .5X million BTUs of hydrogen are providing as much electricity as as X million BTUs would have last year.

They might purchase hydrogen from a supplier who claims to be providing "green" hydrogen, shipped at great expense in LNG container ships from the North Sea, who is instead using hydrogen derived from steam reforming methane at an infinitesimal fraction of the cost, with an emissions footprint orders of magnitude higher.

Many ways to skin the cat (and I'm realizing I'm in the wrong business).

"On the other hand, I was shocked to read that 1400 people work there [Diablo Canyon]: 1200 PG&E employees and 200 employees of subcontractors according to Wikipedia."

Subcontractors are hired for refueling and large maintenance procedures, and are employed for one out of every nine months, max.

"Wow! That would explain why its operating costs are so high."

~500 jobs at Diablo are security-related. At least one involves management of the onsite automatic weapons firing range (they take security very seriously). But largely because nuclear fuel costs next to nothing, overall operating costs for U.S. nuclear are one-third lower than coal, and 26% lower than gas + solar/wind. According to FERC Form 1, Diablo Canyon generates electricity at a marginal cost to PG&E of $.017/kWh - other than hydro, there's nothing cheaper.

The plant isn't being closed because it's uneconomical, but because it's too economical: it doesn't burn enough fuel.

If shutting down Diablo Canyon is crazy, the reason it was approved by the California Public Utilities Commission is even crazier. PG&E has no plans to replace it with anything but new gas plants - plants that will earn the utility (or whatever it becomes) a markup on every cf of gas it bills to ratepayers. That's right - the more gas PG&E burns, the more money it makes. Because utilities aren't permitted to charge a profit on selling electricity in California, PG&E is primarily a fossil fuel company - and here, we come full-circle:

"The most lucrative industry in the world has accomplished far more at advancing the art of fraud over the last 140 years than anything related to providing power, and nearly all of it has been detrimental to the environment."

Stephen, I don't think the ASME paper you reference suggests that a 30% mix of hydrogen and natural gas would reduce turbine efficiency by 10-33% -- or even reduce it at all. In fact the paper seems to be saying that the higher the ratio of hydrogen to carbon in the fuel being burned, the better.

It's really talking about the difference between kerosene vs alcohol vs natural gas for one specific "flex fuel" combustion turbine. However, to the extent that one can generalize from their findings, one would have to conclude that adding hydrogen to the fuel mix would improve efficiency.

The 10-33% figure, I believe, is an assertion that Bob made about the power output from the turbine from burning a mix of hydrogen and natural gas instead of straight natural gas. He's probably right, if one is talking about power output from a fixed volumetric fuel flow rate. Adding hydrogen will definitely lower the energy content per standard cubic meter of fuel. But it will raise the energy content per kilogram of fuel..

Neither of which facts has anything to do with efficiency of the turbine. Efficiency is power output relative to enthalpy (heat content) of the fuel burned. Not relative to mass or volume. I can't see that adding hydrogen would alter turbine efficiency signigicantly, one way or the other. 

Adding electrolytic hydrogen will lower CO2 emitted per megawatt-hour of electrical output. That's after all the selling point for the whole proposal. But we're not talking about mixing hydrogen into the natural gas as a tweak to an existing gas-fired power plant. The proposal would build an entirely new gas-fired power plant to replace the coal-fired plant at Delta. That will have to include building a gas pipeline to supply the new plant with natural gas.

When it begins operation, the new plant will be running on straight natural gas. The promise to replace a portion of the natural gas with hyrogen -- presumably as clean hydrogen becomes available -- is arguably just a gesture to deflect opposition from RE proponents. Whether it comes to pass, once the plant gets built and the natural gas suppliers have both feed planted inside the door, remains to be seen.