Monday, March 4, 2013

How does a bulletproof vest work?

Mention bulletproof vest and this reminds many about the two slain VAT 69 commandos in Lahad Datu, Sabah recently.

In both fatal shooting by intruders, the victims were shot on their heads. Had it been on other parts of the body, they'd have better chance of survival. Because, surely they'd have been equipped with safety vests.

Testing the bulletproof vest. Wikipedia photo.

So, how do bulletproof vests work? Bullet proof vests are common pieces of protective equipment used by law enforcement and private security personnel.

They are designed to disperse the bullet's energy and deform the slug to minimise blunt force trauma. Hard body armour is made of strengthened steel plates. It is strong and effective but also heavy and cumbersome. But some ammunition can even penetrate steel, requiring stronger materials still.

The latest vests employ overlapping super-strength but lightweight composites of ceramic and titanium. Soft body armour is not as strong, but it is more lightweight and less conspicuous to wear. It is woven out of interlacing strands of Kevlar. Like hard body armour, layers of this tough, net-like material deform the incoming bullet, absorbing certain amount of its energy. The wearer would still feel the hit but at a much reduced impact.

TheGreenMechanics: Bulletproof or not, war and conflict should be avoided best as possible!


Further reading here, and ScienceFocus

Friday, March 1, 2013

5.4kWp rooftop solar PV installed at SM St Michael, Penampang

It pays to go green!

The school’s positive spirit and enthusiasm in advocating Renewable Energy has won the hearts of people from Solarsysteme Sachsen GmbH, Germany. As part of its global “dena Solar Roofs Programme”, the company selected SMK St Michael in Penampang, Sabah for the installation of a rooftop solar PV:

Installed capacity    : 5.4 kWp
Solar module          : 24 panels
Panel rating            : 225W
Inverter                   : 2 nos
Energy production   : 6,800 kWh per year, estimated based on 3.5 hours of good sun per day
Storage                 : Back-up System M which stores energy during weekends for use during school days
Monitoring              : Edu/info panel which displays power in kW, energy in kWh and CO savings
Official launching    : March 18, 2013 at St. Michael school.

Solarsysteme's Sylvia Radisch-Siebert (white shirt) and Mandy Radisch (in blue) at St Michael school during the training on PV basics. Photos by Solarsysteme-Sachsen GmbH.
Bottom image (photo by New Sabah Times) shows St Michael students with the completed rooftop solar PV system.

I really hope that the school will allow the general public to witness the launching in March 2013. I'd love to be there.

If we are to fit this into the FIT scheme currently on-going in Malaysia, and assuming TNB/SESB buy the 6,800 kWh energy produced at RM1.40 per unit, this will give annual income of RM9,520 or RM793 a month. This money can be used to offset the school's monthly bill. Quite interesting.


Note: Active links are shown at the end of this article.

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Installation of 5.4kWp rooftop PV system at SM St Michael completed
New Sabah Times
PENAMPANG: Solarsysteme Sachsen GmbH announced that it has completed the installation of a 5.4 kWp rooftop photovoltaic system at SM St Michael in Penampang, Sabah.

The installation is part of the worldwide “dena Solar Roofs Programme” coordinated by the Deutsche Energie-Agentur GmbH (dena) – the German Energy Agency – and co-financed by the German Federal Ministry of Economics and Technology (BMWi) within the initiative “Renewables – Made in Germany“.

Locally known as the Solar Roofs Project Malaysia, the project was initiated in October 2012 in co-operation with the SM St Michael. The school is the first in East Malaysia to be fitted with a PV system. Sabah was chosen due to the state’s great potential on the availability of solar energy.

The school was chosen not only because of the many prizes they have won for implementing green projects, but also because of the school’s positive spirit and enthusiasm in advocating renewable energy. The intention of implementing this project is to further educate the students on PV’s crucial role in improving living conditions around the world, as well as displacing the use of fossil fuels to generate electricity.

The “dena Solar Roofs Programme” was developed by the Deutsche Energie-Agentur GmbH (dena) – the German Energy Agency. Launched in 2004, this programme, co-financed by the Federal Ministry of Economics and Technology, supports German solar energy companies entering new markets.

The PV system installed at the St. Michael Secondary School consists of 24 panels, 2 inverters and a battery system distributed over 41 square metres rooftop of the school, which has 903 students. The solar system generates approximately 6,800 kilowatt hours (kWh) of solar energy per year and helps to offset the school’s utility costs. The system includes a back-up system whereby the energy stored in the battery can be used during a power blackout.

To illustrate the benefits of the rooftop solar system to members of the local community, a display panel has been installed in the centre of the school to display the actual power in kW and the accumulated generated energy (in kWh) and CO2 savings over the entire period.

Donald Malingan, Chairman of the Board of Governors SM St Michael said: “I have nothing to dispute but to thank Solarsysteme Sachsen and dena for their generosity and benevolence in installing the solar panels in the school.”

An official launch will take place at SM St Michael on 18th March 2013. Guests will have the opportunity to see the project and the accomplishments by the students thus far.


Sources and references:
1) Installation of 5.4kW rooftop PV - N.Sabah Times
2) Solarsysteme Sachsen GmbH - dena Solar Roofs Programme

http://www.sesb.com.my/images/stories/news/2013/02/07/2/NSabahT-Installation-of-5.4kWp-rooftop-PV-system-at-SM-St-Michael-completed.jpg

Sizing up wind turbines: How big are they?

For those staying nearby a wind farm, the mighty tall hub with giant fan blades may be your familiar view. But for the rest of us, here is how to get the hint of how big is a standard 1.5MW - 2MW wind turbine.

Study shows that that, the larger the turbine is, the greener the electricity, i.e. smaller carbon footprint. This effect was due both to size of the turbine as well as the learning and experience gained with the technology over time. Currently, as at end-2012, the largest wind turbine is Siemens 6 MW (megawatt) SWT-6.0-154 offshore turbine in Denmark.

Siemens 6MW wind turbine is the largest to date
Siemens 6MW wind turbine Specifications

Rotor
Type                    : 3-bladed, horizontal axis
Position               : Upwind
Diameter              : 154 m
Swept area           : 18600 m²
Speed range         : 5-11 rpm
Power regulation : Pitch regulation with variable speed
Rotor tilt               : 6 degrees

Blade
Type                        : Self-supporting
Blade Length            : 75 m (B75)
Aerodynamic profile  : Siemens proprietary airfoils
Material                   : GRE
Surface gloss           : Semi-gloss, <30 / ISO2813
Surface colour          : Light grey, RAL 7035

Tower
Hub height      : Site specific, could be up to 130 m




The giants are getting bigger!

However, current trend is that wind turbines are getting bigger. In January 2013, British company, Blade Dynamics, announced it was developing blades of up to 100 meters in length dwarfing the size of existing Siemens 75-meter turbine blade. Sitting on top of a tower 170 meters high, the structure will be 270 meters in total.

In comparison, KL Tower stands at 421-metre high while Petronas Twin Towers at 452 metres. So, when completed, Blade Dynamics' 270 metres structure is pretty tall.


Size comparison

Comparing these turbines with other structures, it is easy to see why many people are protesting against large wind farming due to noise pollution and their unsightliness.



How much power can they generate:

Estimated capacity with good wind, i.e. wind blowing within designed range.


Researchers say that bigger wind turbines are more cost effective, but there should be limit somewhere when the cost of building the towers are more that the selling price of electricity generated.

Let's hope they are not near your home.


References (image credits and facts):

1) Wind turbine with the world's largest rotor goes into operation - Siemens
2) Wind Energy - The Facts
3) Solvent Green - Windfall
4) Siemens 6.0 MW Offshore Wind Turbine