July 15, 2008

Global Monitor (July 2008)

U.S. rivers next massive power source?

Major U.S. rivers could soon feed several underwater turbine arrays with their massive power potential if some of the more than 100 projects that a Houston-based alternative energy firm has filed with the Federal Energy Regulatory Commission (FERC) are approved.

Free Flow Power Corp. (FFP) has developed a hydrokinetic turbine generator system that extracts energy from moving water without requiring the construction of new dams or diversion. The company wants to submerge the system, which can be installed in an array of different configurations to suit site conditions, in the Mississippi, Missouri, Ohio, Niagara, and Detroit Rivers (Figure 4).

4. River current. Free Flow Power Corp., a hydrokinetic energy firm, has filed more than 100 projects with the Federal Energy Regulatory Commission to install its turbine generation system in major U.S. rivers. The turbines can be arranged in arrays to suit site conditions. Courtesy: Free Flow Power Corp.

FFP’s turbine uses a rim-mounted, permanent magnet, direct-drive generator with front and rear diffusers and a moving rotor to maximize efficiency. So far, the company’s prototype has undergone land testing and subjection to Alden Labs’ newest test flume, which mimics the flows found in river, tidal, and ocean current environments. Its two-meter version, which is expected to generate 10 kW in flows of 4.5 miles per hour is currently being deployed in a Massachusetts canal test.

Meanwhile, FFP is planning big: In the Mississippi River it plans to place about 150 such generators in a linked system on the riverbed and transmit the hydropower through an onshore converter. And it reportedly proposed installing 875 submerged turbines along a corridor in the Niagara River. Each of the U.S. projects planned would consist of between 900 and 5,000 turbines configured in a series of matrices, the company said on its web site.

Before it can begin mass-producing power, however, the company must garner regulatory approval for a majority of its projects, a process that could take up to five years. Although FERC recognizes that hydrokinetic technologies, if fully developed, could double the amount of hydropower production in the U.S.—bringing it from under 10% to 20% of the national electrical supply—regulatory hurdles continue to be complex.

Siemens delivers 500-MW gasifiers

Siemens Energy has delivered the first two of five massive coal gasifiers—each with a thermal capacity of 500 MW—to Shenua Ningxia Coal Industry Group Co.’s coal-to-polypropylene plant (SNCG) in China.

The gasifiers, which are 59 feet long with an inside diameter of about 10 feet, weigh 220 tons and are capable of gasifying up to 2,000 tons of coal daily. Gasification takes place in a cylindrical reaction chamber at temperatures above the coal-ash fusion temperature. Finely ground fuel that is introduced with a mixture of oxygen, and steam via a burner at the head of the reactor is converted within a few seconds into raw syngas consisting mainly of carbon monoxide, hydrogen, carbon dioxide, and water (Figure 5).

5. Coal gasifier. As recently delivered to a coal-to-polypropylene plant in China, Siemens Energy’s newest 500-MW gasifier is capable of gasifying 2,000 tons of coal daily. Finely ground fuel introduced via a burner at the head of the reactor is instantly converted into raw syngas. Solidified clinker granules can be removed via a material lock at the foot of the quenching chamber. Courtesy: Siemens

Though SNCG will use the five-gasifier plant to produce about 19 million cubic feet of syngas for conversion in downstream processes to polypropylene plastic, the technology can effectively be used for power generation in integrated gasification combined-cycle plants, Siemens said.

Siemens produced the gasifiers in about 18 months, beginning work soon after it acquired the technology for the gasification of fossil raw materials from the Swiss company Sustec Holding AG in 2006.

Algae: A green solution

To stay within shrinking federal and state carbon emission allowances, companies in the U.S. and around the world are scrambling to take up innovative solutions and clean up or cut down carbon dioxide emissions. Amid ongoing gasification tests and carbon sequestration experiments, Massachusetts-based GreenFuel Technologies Corp. has been quietly conducting studies with several companies at their coal-fired plants to develop high-yield algae farm technologies. Its mission: to profitably recycle industrial carbon dioxide and produce feed, food, and fuel ingredients.

A few years ago, the concept would have been dismissed as ineffective, even though for some time now, algae have been used in wastewater treatment facilities to sop up toxic chemicals and at farms to capture fertilizers in runoff. As autotrophic organisms, algae can produce their own food from inorganic substances such as carbon dioxide and inorganic nitrogen. They are the fastest growing plants in the world, and they do not need clean water or land. And from several studies, GreenFuel has found that, as well as recycling atmospheric carbon dioxide, the entire biomass produced from algae can be used and that oil retrieved from the organism could be used as a renewable biofuel.

A company that began operations in 2001, GreenFuel has so far conducted successful pilot installations to recycle carbon dioxide at several plants, including the Redhawk and Four Corners plants owned by Arizona Public Service (APS), NRG’s Dunkirk plant in New York and its Big Cajun plant in Louisiana, and a Sunflower Electric plant in Kansas.

APS and GreenFuel partnered in 2005 and recycled 80% of daytime carbon dioxide emissions from APS’ 1,040-MW gas-fired Redhawk Power Station using an algae bioreactor. The contraption was simple: Carbon dioxide emissions coming out of the stack were directed through specially designed pipes and into specialized containers holding hungry algae. In the presence of sunlight, the algae consumed the carbon dioxide (Figure 6). GreenFuel then converted the carbon-rich algal biomass into transportation-grade biodiesel and ethanol.

6. Hungry critters. An algae bioreactor system connected directly to the stack of APS’ 1,040-MW Redhawk Power Station successfully recycled greenhouse gases into renewable biofuels in 2006. Courtesy: APS

In 2007, APS announced that the team would attempt to replicate its success using emissions from APS’ coal-burning Four Corners Power Plant. Earlier that year, GreenFuel had teamed up with NRG to install the company’s Emissions-to-Biofuels process to capture NRG’s flue gas carbon dioxide. GreenFuel indicated on its web site that both projects were successful, although it did not give any details.

So will the use of algae bioreactors catch on as a commercial solution to the complex carbon dioxide emissions problem? “GreenFuel’s extensive economic analyses and cost estimates show that algae can be grown economically as a commercial product. Many estimates claiming that algae are not commercially viable use outdated economics for product values that are no longer valid, or assume use of initial generations of experimental technology that have since been upgraded,” the company says on its web site. “GreenFuel believes that ecological and energy issues are complicated and will require a variety of solutions—of which algae will be one.”