Domain: siliconvalleypower.com
Stories and comments across the archive that link to siliconvalleypower.com.
Comments · 7
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Re:Woop Di Do Da!
The sad part is that states like Florida are making it harder to install solar. On top of that, Florida is fighting energy efficiency. Other states are adding fees to solar users at the behest of the utility companies.
I live in California and am getting solar installed later this week though not nearly as big of a system as I'd like due to limitations of my roof. PG&E has some of the most expensive electricity in the country because of our state's corrupt public utilities commission. Average rates are around $0.194/kwh (compared to Santa Clara $0.113/kwh). PG&E has been quietly lowering the thresholds to push people into higher tiers of power as they make their homes more energy efficient. On average I'm paying well over $0.19/kwh so solar makes perfect sense.
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Re:Like Obama?
Santa Clara, CA has its own power plant, and this page mentions "all municipal electric utilities of Northern California". So there ARE utilities that are not simply government sanctioned monopolies (by third party companies).
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Re:Physics
Just FYI - a watt is defined as 'the power developed in a circuit by a current of one ampere flowing through a potential difference of one volt." see http://www.siliconvalleypower.com/info/?doc=glossary/, i.e. 1W = 1VA. The dirty little secret about power calculations is that there is another factor thrown in, typically about 0.65, called the 'power factor' that UPS and power supply manufacturers use to lower the overall wattage. That's why you always use VA (rather than the reported wattage) because in a pinch you can always measure both voltage and amperage(under load).
If you don't want to learn anything about AC power, please don't call it a "dirty little secret". Wikipedia for example would be a good place to start.
I'll summarize for you though:
Real Power (P) - has units of W. This is the amount of power dissipated into the "real" (resistive) part of a complex load.
Reactive Power (Q) - has units of VAR (volt-amp reactive). This is the amount of consumed by the reactive (capacitive/inductive) part of a complex load.
Apparent power (|S|, S = P+jQ) - has units of VA (volt-amp). If you plot P and Q on the complex axis, you this is what completes the triangle.
Power factor - ratio between real and apparent power. (P/|S|) For purely resistive loads, this is 1. For purely reactive loads, this is 0.
A UPS is basically just a battery with a bit of supporting circuitry. The battery can only deliver a certain amount of energy per time (some type of power). If this energy is all going to a resistive load, then yes, it would be what you think it is, Watts. This is also the apparent power the UPS can deliver in VA (P=|S|, PF=1). If the load is purely reactive, the apparent power will remain the same in VA, however the real power will be 0. For this reason, UPSs are rated in VA. They can make no guarantee about the amount of real power (W) they can deliver, as it will depend on the load.
Hopefully that makes sense and I haven't confused things further. (power EEs may have something to add/correct, I'm more of an electronics one going off memory) -
Physics
For those of you who either didn't take Physics, or slept through it, Watts and BTU's/hr are both measurements of POWER. Add up all the (input) wattages, and use something like http://www.onlineconversion.com/power.htm/ to convert. This site also has a conversion to 'tons of refrigeration' on that same page.
Also note - Don't EVER user the rated wattage of a power supply because that's what it SUPPLIES, not uses. Instead use the current draw multiplied by the voltage (US - 110 for single phase, 208 for dual phase in must commercial blgs, 220 only in homes or where you know thats the case). This is the 'VA' [Volt-Amps] unit. Use this number for 'watts' in the conversion to refrigeration needs.
Just FYI - a watt is defined as 'the power developed in a circuit by a current of one ampere flowing through a potential difference of one volt." see http://www.siliconvalleypower.com/info/?doc=glossary/, i.e. 1W = 1VA. The dirty little secret about power calculations is that there is another factor thrown in, typically about 0.65, called the 'power factor' that UPS and power supply manufacturers use to lower the overall wattage. That's why you always use VA (rather than the reported wattage) because in a pinch you can always measure both voltage and amperage(under load).
Basically do this - take all the amperage draws for all the devices in your rack/room/data center, multiply them by the applied voltage for that device (110 or 208) and add all the products together. Then convert that number to tons of refrigeration. This is your minimum required cooling for a lights out room. If you have people in the room, count 1100 BTU's/hr for each person and add that to the requirements (after conversion to whatever unit you're working with). Some HVAC contractors want specifications in BTU's/hr and other want it in tons. Don't forget lighting either if its not a 'lights out' operation. A 40W florescent bulb means its going to dissipate 40W (as in heat). You can use these numbers directly as they are a measure of the actual heat thrown, not of the power used to light the bulb.
Make sense?
Dennis Dumont -
Estimate is way too low.Where I live, the power company has a similar plan where you can sign up for "green power" from wind and solar installations. This costs an extra 1.5 cents per kWh, and they estimate that to be about $7 per month for the average household. (And that tracks pretty well with my own power bill.)
And yes, they freely admit that it all mixes together in the power grid. But they buy power from the "green" providers based on the usage of the customers signed up for the program. This means they have to burn less fossil fuel to run their own generators.
If you are curious, you can look at their program information here
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Santa Clara, CASilicon Valley's city of Santa Clara is very environmentally conscious. There are "Tree City USA" signs up all over the place, and the city-owned utility proudly trumpets the breakdown of its energy sources:
It gets 43% of its electricity from hydroelectric dams, 22% from geothermal, and another 4% from other renewable sources.
The city really focuses on finding plausible, cost-effective power sources, but for some reason it doesn't get any of its power from the wind. Perhaps the Santa Clarans know something the Danish don't?
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Re:Energy efficiency?I live in Santa Clara. We have city-owned utilities, so we didn't have rolling blackouts. (or nasty high bills) HA!
Q: As a resident or small business owner, am I going to be effected by rolling blackouts?
A: Possibly. So far, Santa Clara Power Reduction Pool has absorbed the city load reduction obligations. However, if larger or longer load reductions are required, you may be subject to rolling blackouts.Q: How much less do City of Santa Clara residents pay for their electricity?
A: When you compare the City rates to its neighbors, like San Jose, residents enjoy an average of 40% savings.