January 15, 2008

Global Monitor (January 2008)

Google Earth adds air quality data

We’ve all done it—fired up Google Earth and zoomed in on our home or a famous landmark to see how sharp satellite photos have become. You still can’t read license plates, but the view from space is captivating, and “flying” from one target to another is a trip.

3. Air Google. Thanks to a partnership with the U.S. EPA, users of Google Earth can now call up near-real-time air quality data for any location in America. Source: Google Earth

Google recently integrated near-real-time scientific air quality information from the U.S. Environmental Protection Agency (EPA) directly into Google Earth. The program accesses the EPA’s AIRNow database hourly, enabling its new Air Quality Index to display current air quality conditions at any U.S. location. Figure 3 shows two readings for Phoenix called up a month ago.

For more information on AIRNow, and easy instructions for using it with Google Earth, go to www.epa.gov/region09/air/airnow.

Alstom supplies integrated solar/CC project in Morocco

In late October, Alstom was awarded a $234 million contract by Spain’s Abengoa Group, on behalf of Morocco’s Office National d’Électricité, to supply two GT13E2 gas turbine generators, one steam turbine generator, and three air-cooled turbogenerators to the Aïn Béni Mathar power project. The deal includes a 21-year service contract under which Alstom will maintain and help support the operation of the plant, 60 miles from Oujda.

The project seeks to become the world’s first integrated solar combined-cycle power plant. It will have a generating capacity of about 470 MW, 20 MW of which will come from energy collected by a 1.97 million ft² array of single-axis-tracking cylindrical parabolic mirrors in parallel rows. Abengoa Group received a $43 million grant from the World Bank to develop the solar part of the project.

On the solar side, each bank of mirrors is equipped with a linear parabolic reflector that aims reflected sunlight on a receiver at the focus of the bank’s parabola. The energy delivered to the receiver heats a working fluid that’s circulated through it. A series of heat exchangers extracts the energy and feeds it to two heat-recovery steam generators (HRSGs) into which the two gas turbines exhaust (Figure 4).

4. Technology fusion. A simplified block diagram of the 470-MW integrated solar combined-cycle plant that Alstom is building in Morocco. Source: Alstom

As the figure shows, the two gas turbine generators are part of a conventional 2 x 1 combined-cycle configuration. The two systems are tightly integrated: Water used in the solar side’s steam generator is taken from the HRSG’s economizers, and steam generated by the solar field is injected into the superheaters of the same HRSGs. Both flows of steam, generated by the solar field and by the HRSGs, are expanded together by the single steam turbine.