Lincs offshore wind farm gained government consent

On October 21, 2008 Centrica received the official consent to develop a 250 MW offshore wind farm, off the Lincolnshire coast (UK).
Lincs project will be situated at 8 km off the coast east of Skegness and will be next to the recent offshore wind farm developments at Lynn and Inner Dowsing, currently the biggest offshore wind farm in the world.
The completion of Lynn and Inner Dowsing offshore wind farms (194 MW rated power in total) has taken UK in to the lead of world offshore wind industry, bringing UK total installed capacity to a total of about 600 MW. The installation of all the wind turbines was completed during last summer and at the moment 45 of the 54 3.6 Siemens turbines are fully commissioned and producing power. The wind farm is expected to be fully operational by the end the year.
Centrica has also in the pipeline two further projects off the Lincolnshire coast: “Docking Shoal and Race Bank”. These two further offshore wind farms will give further support to Centrica to become a big player in the renewable energy sector, adding 1,000 MW to their wind generating capacity.


Posted by: Filippo

Solar Planes are becoming a reality

Solar aviation traces its roots to the early 1970s, when hobbyists and engineers began using solar cells to power model aircraft. Then, since late ’90 endurance solar flights (day-night cycle) have been realized mainly on unmanned planes. Last summer an unmanned solar plane named “Zephyr” was capable to stay in the air for more than 82 hours (about 3 and half days!). The plane was running on solar power during the day and batteries that were charged by the sun, at night.
Other companies and organizations have also developed similar planes. A solar craft called “SoLong” flew for 48 hours in 2005. The US space agency “Nasa” developed “Helios” vehicle that set and altitude record in 2001 for a non-rocket-powered winged aircraft when it flew up to 29.5 km of altitude.
However, not only unmanned flights have been realised. The Swiss balloonist Bertrand Piccard plans in 2010 to launch “Solar Impulse”, a manned plane in which, in five year time, he will attempt to circumnavigate the globe. A transatlantic flight is planned to be realized already in 2011. In order to be capable to carry a pilot the craft will have a huge wingspan of about 60 m. Furthermore because the plane will be piloted by only one person at time, it will have to make frequent stops and break the journey into various legs.
In May 2008 two Solar Impulse pilots (Bertrand Piccard and André Borschberg), one after the other, spent 25 hours flying non-stop at the controls of a virtual flight in a cockpit identical to the one of the Solar Impulse. The pilots were able to test the ergonomics, the aerodynamic behavior of the plane, the management of the energy consumed by the motors or stored in batteries and the efficiency of these during nocturnal part of the flight.
Being photovoltaic cells capable to produce little amount of power (about 125 watts per square meter with good/optimal solar radiation) the only way to make an airplane flying long distances with so little power is to make it light and with a big wingspan. Solar panels cover almost the entire top surface of the wings and tail.
The prototype should be available by the next summer and the earliest flights will be made under battery power without solar cells, but later tests will be done by applying the complete technology. The team hopes to make several 36 hours flights already in 2009 to demonstrate the ability to fly a complete day-night-day cycle powered only by the sun.
This kind of technology will not replace jetliners in the near future, but it is a great idea to show people what is possible to achieve with renewable energy.


Posted by: Filippo

Resources:
www.solarimpulse.com
www.nasa.gov/centers/dryden/news/ResearchUpdate/Helios/index.html

Heat Pumps: Renewable Energy or not?

Heat pumps are a means of converting work energy into heat energy in a process analogous to a reverse heat engine. Thermodynamically, an ideal heat pump cycle is the most efficient means of generating heat energy at a temperature above ambient - i.e. heating a room.

What is more, heat pumps extract most of this heat energy from the environment - a renewable energy source. A smaller part of the energy is supplied in the form of work energy, renewable or otherwise ....The heat transferred between a cool environment and a heated room for a given amount of work is theoretically given by the system's COP. For an ideal cycle operating between a environment at Tc and a heated room at Th this is given by 1/(1-Tc/Th). For typical exterior and interior temperatures of 10 degrees C (283K) and 20 degrees C (293K) the COP is an impressive value of more than 29.

This means that an ideal heat pump consuming 1kW of electric power for work delivers 29 times more energy than an electric element heater, with at least 28 kW of this heat energy being extracted, renewably, from the environment.

In real systems, with their non-ideal cycles and realistic system limitations, the COP rarely exceeds 4. Nevertheless, this still looks distinctly impressive compared to simple resistive electric and fossil fuel combustion heating systems. Who wouldn't want a heating system with an "efficiency" of 400% ? (more on the topic of heating efficiencies later maybe).

A so called "Primary Energy" analysis reveals a slightly different picture, perhaps. If the electricity is generated in conventional fossil-fuel combustion power plants, where work is generated from heat and then converted into electricity, a plant "energy efficiency" of 30% is quite typical. In the UK, for instance, the remaining 70% of the energy is mostly discarded as waste heat energy to the environment (in those distinctive wide parabolic-sided chimneys). If electric energy is used to drive a heat pump with a COP of 3.3, we have just recovered the heat energy initially lost to the environment - and we haven't even accounted for distribution losses. Now our "energy efficiency" appears to be well under 100%. Not as impressive! (conventional gas condensing boilers routinely exceed energy efficiencies of 90%)

So why not use the fossil fuel, on-site, in an engine to supply work directly to the heat pump and then capture the "waste" heat energy of the engine in our heating system - a classical co-generation approach. A quick calculation shows that a gas engine with a work efficiency of 25% driving a heat pump with a COP of 3.3 yields a primary "energy efficiency" of 158%. Now that's a bit better! ..... (unless these efficiencies of >100% are beginning to irritate you - in which case you'll have to wait for the next instalment on this topic)

Tidal power – Tidal stream generation

A relatively new technology, tidal stream generators draw energy from currents in much the same way as wind turbines. The best way to understand the mechanism of the generator is to think of it is an underwater windmill. The higher density of water, 832 times the density of air, means that a single generator can provide significant power at low tidal current velocities (compared with wind speed).

The advantage of this kind of source is its predictability (predictable as the phases of the moon).

Tidal stream power systems need to be located in areas with fast currents where natural flows are concentrated between obstructions, for example at the entrances to bays and rivers, around rocky points, headlands, or between islands or other land masses.[1]

First tidal power turbine got plugged to the network[2]

An underwater turbine that generates electricity from tidal streams was plugged into the UK's national grid on the 17th of July 2008. It marked the start of a new source of renewable energy for the UK.

Tidal streams are seen by many as a plentiful and predictable supply of clean energy. The most conservative estimates suggest there are at least five gigawatts of power in tidal flows around UK, but there could be as much as 15GW.
The trial at Strangford Lough, in Northern Ireland, uses a device called SeaGen (www.seageneration.co.uk). During the testing phase its power is limited up to 300kW. However, when it will eventually run at full power the turbine is expected to generate 1.2 MW.

SeaGen was designed and built by the Bristol-based tidal energy company Marine Current Turbines (MCT).

The cost of installing the marine turbines is £3m for every megawatt they eventually generate, which compares to £2.3m per megawatt for offshore wind. The costs will drop if the technology is more widely adopted.
After SeaGen will start to operate at full capacity the plans of MCT is to build a farm of turbines before 2011. Their next site will be off the coast of Anglesey and the initial farm will be about 10.5MW. It seams that the resource up there is around 350MW."

The Pentland Firth, the Channel Islands and the Severn estuary are also other potential hotspots for tidal energy in UK.

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Tidal Power in the waters of the East River off Roosevelt Island[3]

At the other side of the Atlantic Ocean, near by New York, other people are also working to similar installations.

A third generation of experimental turbines has been installed by Verdant Power (www.verdantpower.com) in the waters of the East River off Roosevelt Island. The East River is not a real river, but a tidal strait connecting Long Island Sound to Upper New York Bay.

The first two generations of turbines were installed in late 2006 and early 2007 and the company gained a lot of knowledge from their breakdown and trouble shooting.
These kinds of generators have been designed so that they are automatically swung by the tidal currents and always face the right direction of the current. They sit on piles drilled into the riverbed and at low tide are six feet below the surface. Underwater power cable links the generator to Roosevelt Island.

The original turbine blades were fiberglass stretched over a steel skeleton, but apparently they broke on the first deployment. Thus, new blades were fabricated from aluminum magnesium, and they held up well, but the flowing water found the next weak point in the machines, along the rotors, or hubs. These snapped within two months. Now, the new generation is provided with new aluminum alloy blades fixed to hub.

In my personal opinion this kind of energy, if applied in the right places, could be another good example of renewable energy and could make a massive contribution to Britain, and to other countries with similar resources, cutting CO2 and fuel consumption. The main issue is that there are few places in the world where this kind of technology can be properly applied. My hoping is that tidal stream generation, like wind, will become a significant reality and contributor to the future mix of energy.


Posted by Filippo

Resources:
[1]: Wikipedia – accessed on September 3, 08
[2]: Guardian magazine, UK - Thursday July 17 2008
[3]: New York Times, USA - Thursday August 23, 2008