OTEC Beats OPEC?

The key to energy independence could be just off our shorelines.  No, not the oil buried under the sea floor, but the water itself. The water in the ocean at depths greater than a half-mile are significantly cooler than the water at the surface. It is a fundamental teaching of thermodynamics that a difference in temperature between two materials can be converted into other types of energy.

An example of this is the conventional power plant using fossil fuels.  Fuel is burned to heat water, creating steam, and this heated fluid can then be used to turn a generator as it expands and cools, changing the thermal energy of the steam into first mechanical energy to turn the generator, then the mechanical energy of the generator is turned into electrical energy.

In the case of Ocean Thermal Energy Conversion (OTEC), the warm water at the surface of the sea is used to boil ammonia, which has a very low boiling point.  The ammonia vapor is then used to drive a turbine which spins a generator to create electrical energy.  

Once the energy has been extracted from the ammonia in this way, it must be cooled down in order to turn it back into a liquid, so that the cycle can be repeated.  To do this, the cold water from the ocean depths is brought to the surface through large vertical pipes.  This cold water re-condenses the ammonia, making it ready to begin the process again.

The design of a prototype plant to test all this is being explored by Lockheed Martin, the aerospace company.  A plant to generate power in this way would be a huge undertaking.  The pipes that descend into the ocean might be as much as 30 feet in diameter, and over 3000 feet long.  The first test site is expected to be off the shores of Hawaii, where they hope to build a plant with a capacity of 10 to 20 MW.

Inflatable Tower - Gateway to Space?

A new and totally different concept for reaching the lower levels of outer space has been proposed by researchers Brendan Quine, Raj Seth and George Zhu at York University in Toronto, Canada. Their concept is a much cheaper (and much lower altitude) version of the "Space Elevator" concept that has previously been proposed (see previous article below).  Unlike the Space Elevator, which reaches up to or above a geosynchronous orbital altitude (35,786 km, or 22,236 mi above mean sea level), this new concept would reach only about 15 - 20 miles altitude, or about 1% of that height.  Technically, this represents the "threshold" of space, where the sky would be black, and you could clearly see the curvature of the earth - you would be able to see about 600 km (373 mi) to the horizon.

The tower concept is based on a modular construction using elements like the ones in the photograph.  The hollow tubes would be made of a Kevlar®-polyethethylene composite, and inflated by helium or other low-density gasses.  The model shown in the photo is 7 meters tall (23 ft), and consists of six modules stacked end-to-end.  The tubes are made of poly ethylene, and are 8 cm (3.14 in) in diameter.  To reach an altitude of 15 km (9.3 mi), the device would require 100 modules, each one being 150 meters (492 ft) tall and 230 meters (755 ft) in diameter.  The total structure would weigh about 800,000 tons, equivalent to 2 supertankers.  The designers state that the structure could be built with materials available today, and point out that with the proposed design, the failure of a few of the elements would not result in the collapse of the entire structure.

Stairway to Heaven? How About Just Taking the Elevator?

One of the most daring concepts for reaching orbital space around the Earth is the Space Elevator.  This transport to space is based on the seemingly simple idea of a "rock on a string" - visualize tying a weight to a string and swinging it over your head.  The difference here is that the "string" would be anchored at the equator of the earth, and would be over 35,000 km (22,750 mi), and could not be made using any materials that are currently available.  The most likely candidate for such a tether is some sort of composite made of carbon nanotubes.   These microscopic fibers, while currently being made in multi-gram quantities, would be needed in vastly larger quantities to fabricate a cable long enough to wrap around the earth.

Still, there is a lot of serious preliminary work being done on this concept, in various configurations.  The big driving force is the possibility of a huge reduction in the cost of placing material into orbit.  Currently, using conventional chemical rockets, it costs around $15,000 - $20,000 to lift one pound into a geosynchronous orbit.  With a functioning Space Elevator, the cost might be reduced into the $200 range.  The big reason for this huge cost reduction is that for a conventional rocket, most of the fuel used at the beginning of a trip is expended just lifting the fuel needed at the end of the trip.  The Space Elevator would avoid this inefficiency by using energy beamed up from the ground by lasers.

Mars Rover "Spirit" Engages in Navel Gazing

The Mars Rover "Spirit" which has become bogged down in fine soil on Mars since early May was instructed to use a microscope imaging system to look underneath its belly to try to determine exactly how and why it has become stuck.  With only five of its original six drive wheels working, it is in a relatively serious predicament. It is thought that one other wheel may now be jammed by a rock, and the vehicle is tilted at an angle of about 14° because of the terrain on which it sits. NASA Engineers plan to continue taking pictures with the camera, and will try to simulate the situation here on Earth to figure out the best way to attempt to free the Rover.

Monster Engine Drives Huge Container Ship

This is one serious engine!  It is literally the size of a five-story building.  It was built for a Container Ship: the Emma Maersk, one of the new super-ships that have been coming out of shipyards recently.  The construction of the ship was not without incident - they had a significant fire during construction.  The details of the engine's design and construction are nothing short of incredible.  Weighing in at 2300 tons, the engine output is rated at 108,920 hp at 102 RPM, producing 5,608,312 foot-pounds of torque.  It is remarkable what can be built these days.  When you look at the full-size picture, notice how many wheel axles are on the flatbed trailer!