The Bottom Line on the New Energy Economy
Solar Thermal Electric

Solar You Can Count On 
Hybrid Solar/Natural Gas Plants Provide Power When Needed

Source: Skyfuel                                                       Source: BrightSource Energy

August 18, 2009
by Craig Severance

By far the largest source of safe, clean energy that will never run out  (i.e. renewable energy) available in the United States is the sunlight falling on the unused deserts of the Southwest.  This attractive source of energy produces no nuclear waste, no carbon dioxide or mercury emissions, and none is imported from foreign countries.

According to the U.S. Department of Energy enough sunlght falls in just the unused, nonsensitive areas of our SW deserts to generate over twice the total kWh's now consumed in the entire U.S..

SW Solar Now.   In June, Interior Secretary Ken Salazar opened up 24 of  the SW's sunniest areas on Bureau of Land Management lands in six  states to begin leasing for installation of up to 100,000 MW of solar power plants. (See here for article on the Interior Department announcement).  The first plants could be operating within 3 to 4 years in these ideal locations, which were chosen for maximum clear sunny days and minimal impact on the environment or other land uses.

Sun Doesn't Shine All the Time.  Although the SW sunshine resource is enormous and largely untapped, critics of solar energy routinely note the sun does not shine all the time.  The implication is that power is needed all the time, and since the sun is not always available, solar opponents say it would be foolish to invest in generating electricity from the sun. 

Grid Can Use Solar.  Utilizing solar electricity when the sun does shine is not really a major problem for the electric grid, until the percentage of power generated by solar reaches high percentages.  This is because roughly 50% of the electrical capacity on the grid consists of load-following power plants (chiefly natural gas and hydroelectric), which can quickly reduce power output when a renewable resource such as solar or wind is available, and increase output when needed.  The ability of the grid to absorb a high percentage of  power from renewables has been documented by the U.S. Department of Energy and was discussed in my article "The Wind does NOT Blow Only 1/3 of the Time" here.

The output from a solar power plant also fits very well with the times when  power is most needed.  Most utilities see increased demand for electricity during daylight hours, with peak demands occurring on hot sunny days when a solar power plant produces well.  By the same token, less power is needed at night.

It is generally agreed, however, that extending the percentage of  our electricity generated by renewable power sources above 20-30% will require means to better regulate the grid (see "Smart Grid" article here),  more efficiently supplement renewable power, or store it for later use. 

Solar Thermal Offers More Choices.  Solar photovoltaics (PV) require storage of their electrical energy output to extend their use into evening and cloudy hours.  Methods the electric grid can use to store electrical energy include batteries, flywheels, pumped hydro or compressed air energy storage.  

The "other" kind of solar power -- Solar Thermal power -- offers more choices to integrate with the grid to provide reliable power. 

Instead of directly converting the sun's rays into electricity, Solar Thermal plants use mirrored surfaces to concentrate sunlight to produce high temperatures.  This is why they are also called Concentrating Solar Power (CSP) Plants.

The high temperatures are used to boil water to produce superheated steam to generate electricity.   This different technology means there are now three different ways that Solar Thermal power plants can provide power when the sun is not shining:

1.   Integrate a back-up source of heat (e.g. natural gas) to produce steam.
2.   Produce excess solar heat during the day, and store that heat.
3.   Grid storage of electrical energy (as with PV or wind).

This expansion of choices means that a Solar Thermal plant can function as a reliable source of "24/7" power to the electrical grid.

Click here to read entire article.

BLM Opens Doors for SW Solar Grand Plan

Map of SW Solar Resources on BLM Lands. 
Source: BLM.

July 2, 2009
by Craig Severance

Just a year and a half after a breakthrough 
Solar Grand Plan study was published in the January 2008 Scientific American, the U.S. government has begun plans to implement major elements of such a Plan.

Measures announced Monday by the U.S. Department of the Interior identified initial solar project areas for the extremely sunny desert areas of the U.S. Southwest.  These Solar Energy Study Areas could site utility-scale solar projects totaling 100,000 MegaWatts (MW) capacity. By comparison, the extremely successful U.S. wind energy industry had total installed capacity by the end of
1st Qtr 2009 equaling 28,206 MW, and "new nuclear power" Generation III+ nuclear plants installed worldwide to date equals zero MW. 

Salazar Announces BLM Plans to "Fast-Track" Solar.  On Monday, U.S. Interior Secretary Ken Salazar, appearing in Las Vegas with Senate Majority leader Harry Reid (D-NV), announced Bureau of Land Management 
(BLM) plans to move quickly on solar projects in the desert Southwest.  Plans to "Fast-Track" solar include:
  • Identification of 24 "Solar Study Areas" in 6 Western States, on land administered by the BLM. (Click here for detailed state-by-state maps of the Solar Study Areas.)
  • In-depth evaluation of these 24 areas will begin immediately for their suitability for "large-scale solar energy production".
  • The 24 areas will be segregated from new mining claims and other actions initiated by third parties under public land laws.  Existing claims will be honored. This segregation will allow solar resource plans to be evaluated and authorized first before conflicting new resource claims would be considered.  The BLM noted that "most of the solar energy study areas are located in alluvial valleys are unlikely to contain significant mineral values".
  • 4 new BLM Renewable Energy Coordination Offices -- in Nevada, California, Arizona, and Wyoming (which has major wind resources) will be opened to expedite processing of renewable project applications  The NV office opened Monday.
  • The BLM has already received applications for 158 SW solar projects.   The new processes are expected to complete study area evaluations by the end of 2010, with construction of approved projects to begin thereafter.  
Optimum Areas Selected.  The announcement by Interior follows exactly two weeks after release on June 15th of the Western Governor's Association "Western Renewable Energy Zones - Phase 1 Report", a collaborative effort of the Western Governors, the U.S. Dept. of Energy, the Interior Department, and the Federal Energy Regulatory Commission.  BLM's "Solar Energy Study Areas" were clearly developed in concert with the Western Governor's Association project.

Click here to read full Article.



by Craig Severance

Solar power from the sunny Southwest could soon provide relliable and cost-effective electricity, using a new power plant designed to operate around the clock.  The proposal could answer naysayers who have argued that solar is impractical as a power source because the sun does not shine all the time. 

The new power plants would combine solar and natural gas in one power plant, sharing a common steam turbine.  Bob Fishman, CEO of solar company Ausra, said today that combining the two technologies in one facility can slash one third off the cost of solar power, reducing total generation costs to around 7 to 8 cents/kWh.   

Ausra's solar thermal concentrating power plants are already a leading technology in the effort to develop electricity from the sun.  They work by using a field of mirrored-surface reflectors that concentrate sunlight on tubes filled with water, producing steam to turn a turbine that generates electricity.

Unlike solar photovoltaic panels or wind generators that must use batteries if power needs to be stored, Ausra's steam plants can generate extra heat during daylight hours and store it as very hot fluids, often as molten salts.  These very hot fluids are then used during cloudy and nighttime hours to continue production of steam to run the generator, extending power plant operation several hours into the evening.

While Ausra's design provides power during peak usage hours when electricity is most needed, the design has not reached full 24/7 power production entirely from solar energy.  Fishman also noted that as stand-alone power plants solar power is now costing 12 to 13 cents per kWh.   While this is significantly less than solar photovoltaic panels, it is still more expensive than most fossil fuels.  

Because the solar steam power plant cannot operate full time, a utility will often run a load-following natural gas turbine to provide a backup power source.  Fishman's proposal would simply combine both the solar and the natural gas heat sources in the same facility, sharing a common steam turbine.   The savings from sharing a turbine, and having zero fuel cost solar power most of the time, bring total costs down to a very competitive level. 

Fishman made the comments at the Always On Going Green East conference held in Boston, MA, a conference where leading greentech companies present their business plans to a group that includes investors, bankers, journalists, and their peers.  Always On Going Green East's major sponsors included Always On, EcoWorld, Scientific American, Morgan Stanley, and KPMG. 

This Article was originally posted on March 11, 2009.
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