Renewable Energy

The Desert Can Produce Food and Fresh Water with Seawater Greenhouses

February 10, 2009 - 09:59:36 PM

The Process

The Seawater Greenhouse uses the sun, the sea and the atmosphere to produce fresh water and cool air. The process recreates the natural hydrological cycle within a controlled environment. The entire front wall of the building is a seawater evaporator. It consists of a honeycomb lattice and faces the prevailing wind. Fans assist and control air movement. Seawater trickles down over the lattice, cooling and humidifying the air passing through into the planting area.

Sunlight is filtered through a specially constructed roof, The roof traps infrared heat, while allowing visible light through to promote photosynthesis. This creates optimum growing conditions - cool and humid with high light intensity.

Cool air passes through the planting area and then combines with hot dry air from the roof cavity. The mixture passes through a second sea water evaporator creating hot saturated air which then flows through a condenser.

The condenser is cooled by incoming seawater. The temperature difference causes fresh water to condense out of the air stream. The volume of fresh water is determined by air temperature, relative humidity, solar radiation and the airflow rate. These conditions can be replicated in the thermodynamic model and, with appropriate meteorological information, the detailed design and performance of the Seawater Greenhouse can be optimised for every suitable location and environment.  READ MORE »


Hudson River Science Barge: Hyrdoponic Urban Farming

January 06, 2009 - 08:03:44 PM

Via the website of New York Sun Works - Sustainable Engineering

See the Video 

What is the Science Barge?

The Science Barge is a prototype, sustainable urban farm and environmental education center. It is the only fully functioning demonstration of renewable energy supporting sustainable food production in New York City. The Science Barge grows tomatoes, cucumbers, and lettuce with zero net carbon emissions, zero chemical pesticides, and zero runoff. It is powered by solar, wind, and biofuels, and irrigated by rainwater and purified river water.  READ MORE »


Low Velocity Hydro Power By VIVACE (Vortex Induced Vibrations Aquatic Clean Energy)

January 02, 2009 - 08:32:56 PM

Harnessing the current: An artist's rendition of how a commercial VIVACE system might look. Passive bars, positioned horizontally, are boxed together in a single unit that could be placed at the bottom of a river or in the path of an ocean current. Dozens of 500-kilowatt units could be grouped together in different configurations to create multimegawatt systems.
Credit: Vortex Hydro Energy 

The world's river and ocean currents carry an enormous amount of kinetic energy, but most of this water flows slower than four miles per hour. Existing turbine and water-mill technologies can't generate enough electricity at such speeds to make their deployment economically viable.

Researchers at the University of Michigan say that they have overcome this limitation by taking advantage of energy-packed vortices that are formed when water flows past a cylindrical object, even at low speeds. Salmon and trout are known to leverage the force created by these naturally occurring water swirls so that they can swim upstream. A new mechanical device designed to economically harvest that energy and convert it into electricity could turn waterpower into a much larger part of the world's renewable-energy mix.

"Anywhere we have currents, we can use it," says Michael Bernitsas, a professor in the department of marine engineering at the University of Michigan. He says that the first test of the device will be in the Detroit River, likely in 2010. "If we make it work, and I believe it will, it's going to be a major development," he says.  READ MORE »


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Portugal Launches First Commercial Scale Wave Energy Farm

December 26, 2008 - 11:25:46 PM

Pelamis Wave Power Ltd.  (PWP) is the manufacturer of The Pelamis Wave Energy Converter, a unique system that generates renewable electricity from ocean waves.
 
It is the result of many years of engineering development by PWP and according to PWP is the world’s first commercial scale machine to generate electricity into the grid from offshore wave energy. And "Aguçadoura" is the first wave farm to reach commercial scale. The project is located  5km off the Atlantic coastline of northern Portugal (substation at Aguçadoura) and was developed for Enersis / Babcock & Brown.

The fully operational wave farm consists of three P1-A Pelamis machines with a generating capacity of 2.25 MW (3 x 750kW) which according to Alternative Energy News will produce enough energy to power 1500 homes at peak hours.  READ MORE »


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New Design for Wind Turbine Could Generate Electricity at 1/2 the Cost of Conventional Turbines

December 26, 2008 - 11:15:14 PM


 

Credit: FloDesign Wind Turbine

FloDesign Wind Turbine, has developed a wind turbine that could generate electricity at half the cost of conventional turbines.

The company recently raised $6 million in its first round of venture financing and has announced partnerships with wind-farm developers.

The company's design, which draws on technology developed for jet engines, circumvents a fundamental limit to conventional wind turbines. 

Video by FloDesign Wind Turbine

Typically, as wind approaches a turbine, almost half of the air is forced around the blades rather than through them, and the energy in that deflected wind is lost. At best, traditional wind turbines capture only 59.3 percent of the energy in wind, a value called the Betz limit.

FloDesign surrounds its wind-turbine blades with a shroud that directs air through the blades and speeds it up, which increases power production. The new design generates as much power as a conventional wind turbine with blades twice as big in diameter. The smaller blade size and other factors allow the new turbines to be packed closer together than conventional turbines, increasing the amount of power that can be generated per acre of land.  READ MORE »


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The Pickens Plan

July 27, 2008 - 10:42:14 PM
T. Boone Pickens ideas about wind energy make sense but as Greg Watson points out in his superb blog "12 Degrees of Freedom" we'd be far better off converting the nation's vehicle fleet to electric power instead of natural gas. For a detailed explanation as to why this is true, see the following article by Harvard professor Michael McElroy. (JA)

 

The Pickens Plan:

America is addicted to foreign oil.

It's an addiction that threatens our economy, our environment and our national security. It touches every part of our daily lives and ties our hands as a nation and a people.

The addiction has worsened for decades and now it's reached a point of crisis.

In 1970, we imported 24% of our oil. Today it's nearly 70% and growing.

As imports grow and world prices rise, the amount of money we send to foreign nations every year is soaring. At current oil prices, we will send $700 billion dollars out of the country this year alone — that's four times the annual cost of the Iraq war.

Projected over the next 10 years the cost will be $10 trillion — it will be the greatest transfer of wealth in the history of mankind.

America uses a lot of oil. Every day 85 million barrels of oil are produced around the world. And 21 million of those are used here in the United States.

That's 25% of the world's oil demand. Used by just 4% of the world's population.

Can't we just produce more oil?

World oil production peaked in 2005. Despite growing demand and an unprecedented increase in prices, oil production has fallen over the last three years. Oil is getting more expensive to produce, harder to find and there just isn't enough of it to keep up with demand.

The simple truth is that cheap and easy oil is gone.

What's the good news?

The United States is the Saudi Arabia of wind power.

Studies from around the world show that the Great Plains States are home to the greatest wind energy potential in the world — by far.

The Department of Energy reports that 20% of America's electricity can come from wind. North Dakota alone has the potential to provide power for more than a quarter of the country.

Today's wind turbines stand up to 410 feet tall, with blades that stretch 148 feet in length. The blades collect the wind's kinetic energy. In one year, a 3-megawatt wind turbine produces as much energy as 12,000 barrels of imported oil.

Wind power currently accounts for 48 billion kWh of electricity a year in the United States — enough to serve more than 4.5 million households. That is still only about 1% of current demand, but the potential of wind is much greater.

A 2005 Stanford University study found that there is enough wind power worldwide to satisfy global demand 7 times over — even if only 20% of wind power could be captured.

Building wind facilities in the corridor that stretches from the Texas panhandle to North Dakota could produce 20% of the electricity for the United States at a cost of $1 trillion. It would take another $200 billion to build the capacity to transmit that energy to cities and towns.

That's a lot of money, but it's a one-time cost. And compared to the $700 billion we spend on foreign oil every year, it's a bargain.  READ MORE »


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