Google and Green Renewable Energy

Google is increasingly using renewable energy. Previously they've announced their commitment to carbon neutrality in 2007. They have already invested $94 million in four solar photovoltaic (PV) generators near Sacramento, CA. (See what is PV generator and how it works). These projects have PV systems with a total capacity of 88 MW. Now Google signed an agreement with their utility to supply their Oklahoma data center with 48 MW of wind energy from the Canadian Hills Wind Project.

So, let's do a little math. Depending on the utility's territory, the green power generally costs from 0.5 to 2.5 cents per kilowatt hour more than regular electricity. Assuming the best deal, which is extra $0.05/kWh, each MWh is extra $50. Then 48 MW adds extra 50x48=$2400 each hour. Over an entire year 48 MW of green electricity may cost Google 2400x24x365=$21 million dollars more. In reality, their losses may be less because renewable energy systems rarely work at their maximum capacity. On the other hand, they can be as much as $100 million is they will be charged extra 2.5 cents per kWh. Read more about Google "green" energy activity.

China Safety Standard- Higher Clearance for Power Supplies

We used to think that if our power supply design meets IEC or corresponding UL requirements for a given application, we would automatically meet most national standards of other countries. Now, the main ITE Standard in China GB 4943.1-2011 appears to set more stringent requirements to ITE equipment. Although in general, GB 4943.1-2011 is based on IEC 60950-1 2nd addition, it includes certain deviations. Particularly, par.1.1.2 states that unless specified by manufacturer, the equipment is to be used up to 5000m altitude above sea level. Therefore, in the absence of the marking of par.1.7.2.1 specifying the altitude below 2,000 m, the equipment shall comply with the requirements for 5000m altitude. For such equipment, the minimum electrical clearance has to be multiplied by the factor of 1.48.
In many offline SMPS the minimum UL required creepage between primary and secondary circuits is 6.4mm. If both primary and secondary circuits are located on the same side of PCB, this number also determines the spacing (clearance) between the circuits. With the new China standard that goes into effect December 1, 2012, this spacing will now have to be greater than 9 mm. Note that GB 4943.1-2011 will apply to not only the devices for use in the China, but to all those produced there too. So, if you manufacture power supplies in China, in my understanding, you either need to redesign the PCB and replace certain surface mount optocouplers (if any), or add a warning label showing that your PSU is not for use above 2000m.

Connecting An Emergency Generator

There are two basic methods of connecting your devices to an emergency power generators:

• Via a pre-wired transfer switch;
• Via extension cords.

The transfer switch method can be used for both stationary and portable generators. Portable generators are connected via a manual transfer switch. The stationary standby home systems usually use an automatic transfer switch. It automatically isolates your home from the grid and starts up the generator when it detects a power outage.
A transfer switch installation and wiring requires a licensed electrician and obviously takes time. If you are caught off-guard by a blackout, you’ve got to use a portable genset with extension cords. This is the case today, when more than 3 million people in mid-Atlatic are still without power after a sudden storm. Unlike hurricanes that give you about a week of warning, this storm gave all the impact of a hurricane without any warning. Unfortunately, the extension cords can be used only for cord-and-plug appliances. Connecting lights and hard-wired appliances to a portable generator will not be simple. There are some emergency methods of connecting hard-wired devices, but they may require a professional help. In any case, here are the main two things you need to remember:

• Whenever you run a generator, it must be isolated from the utility lines;
• A generator can be run only outdoors with exhaust pipe located away from house.