[PeakOiler]

[web]http://abcnews.go.com/Technology/story?id=98531&page=1[/web]

Please read the article. Is the concept too far fetched?

Lets see, a virtually non-ending source of renewable energy in Alaska's Aleutian Islands, namely geothermal and wind, which could be a good place to start making lots of hydrogen. (How much could be produced?) If the primary source of electricity is from geothermal and wind, then who cares about the energy loss from the primary source if it's infinite (at least in time if not quantity) to make H2? If a natural gas pipeline can be built from Alaska's north shores to the lower 48, why can't a hydrogen pipeline be built from the Aleutians to the lower 48? I understand Japan builds all their new pipelines to carry both nat gas and H2.

Please feel free to shred this article's concept.

I'm really more interested in any responses to the article.

[Hegel]

How are you going to store and ship these amounts of hydrogen?

[PeakOiler]

How are you going to store and ship these amounts of hydrogen?

I would think that since hydrogen is simply an energy carrier, that it would be used immediately at the other end of the pipeline via fuel cell "substations" (similar to what Long Island, NY is doing with all their General Electric/Plug Power LIPA natural gas-fed fuel cells) which supplement the grid up there. Why store it? Isn't that one of hydrogen's biggest problems?

[donshan]

Since I managed several geothermal projects for 15 years I was interested in this article. Unfortunately the ABC reporter does not give me enough information to assess the potential energy available. Take this quote from the article:

So Wescott traveled out the Aleutians, drilling a few test wells along the way, and he found just what common sense would suggest should be there. The rocks beneath the surface were very, very hot.

"There are several obvious resources out there" which could be used to produce geothermal energy, Wescott says.

What he had found was an enormous potential source of energy, located in a remote area of the planet where only a handful of people live. Except for a few scattered native American villages, and an occasional U.S. military installation, the Aleutians are uninhabited. So here was the potential for a series of power plants in nobody's back yard, drawing electricity from natural resources that should produce energy for many, many centuries

Finding "very, very hot rocks" is NOT what you need for a commercial geothermal electric plant. What is needed is a huge amount of very hot water or steam with underground geology and hydrology to sustain highly pressurized water or steam flows of thousands of tons per hour for decades. The water or steam source needs to be at least 200C (392F) or higher. Water at 200C is under considerable pressure. When it reaches the surface it flashes to steam in a steam separator device. This steam is then sent to a conventional turbine at fairly low pressures of 15 to 100 psi. Sustained volume of steam or very hot, pressurized water is the key. Underground temperatures can be estimated from water chemical measurements of the amorphous silica content or Na/K ratios which can relate the the temperatures of rocks where the water source originated. Had the article even mentioned water geochemistry I would be more encouraged about the potential, since such measurements are always done. Some "binary cycle" geothermal plants have been tested for lower temperature sources. The binary cycle uses hot water to heat a liquid like freon or isobutane and boils that to drive a turbine. These plants are more complex and expensive.

For example the article cites the Geysers field north of San Francisco, which I have visited several times. This is an exceptional geothermal resource where dry steam well bores measure 240 C (464F) at over 200 psi. The important fact is reservoir properties that permit flow rates of over 50 tons per hour of steam year after year from each well and the reservoir supports hundreds of well bores . In 1976, 75 wells produced 500 Mw of electric power. This now has been expanded to about 2000 Mw. However just like oil reservoirs, as steam production expanded, the pressures dropped. Water re-injection was started, but even with this the Geysers field now has a declining power capability. "Peak Steam!!!"

Thus the Alaska potential needs to be defined not by "hot rocks" but by the hundreds of tons per hour of steam available to drive a electric producing steam turbine. Very few sites have this kind of huge volume production.

Further, there are environmental problems since hydrogen sulfide gas is often emitted in large quantities, and the waste waters are loaded with toxic minerals. These typically are now re-injected, but this means more expensive wells. Once steam is flashed off the boiling water, the waste water becomes supersaturated with minerals, plugging pipes, pumps and wells- a maintenance nightmare in some geothermal projects. In volcanic areas like Alaska it would be expected that the hot water would be acidic from dissolved H2S, and possibly HCL and SO2. This creates high corrosion of well casings, pipes and power plant items. Using corrosion resistant metals could make the plant uneconomical in capital expense.

Geothermal wells take the same type of drill rigs used in oil production and typically go a few thousand feet deep. In oil drilling economic success is barrels per day. In geothermal, unless you hit extremely permeable water reservoir structures that are rapidly replenished from a huge underground aquifer it is not economic to drill.

These are some of the data needed to assess Alaska sites. Also however, finding a site that can produce more than a few hundred MW of electrical power is rare. This is a useful size, but is not the thousands of MW of power needed for a significant hydrogen installation. Further to liquify hydrogen gas takes about 60% of the energy value just to liquify it.
So, while interesting I see a lot of obstacles.