Archive for May, 2011

Six more study tips for the CFA exam.

Although it was off-topic, probably my posting with the most long term staying-power was the 2008 article Six Tips For CFA Candidates

I just read another six study tips from the Finance Professional’s Post (published by NYSSA, the NY chapter of the CFA Institute), which focuses on study habits. Since I still have so much traffic even after 3 years, and the advice is good, I thought I’d share.

Here’s the link.

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A Greener Way to Shorten

I’ve been using bit.ly as a url shortened for a couple years now, and never stopped to wonder which country is “.ly”. It turns out it’s Libya. As in a Libyan firm whose chairman is Col. al-Qaddafi’s eldest son, Mohammed al-Qaddafi, not the rebels.

Sure I could just switch to one of several even shorter url shorteners, like r.im… except tha one seems to be down. Maybe goo.gl… at least they can keep a website up.

The same people who brought you JouleBug (of which I’m a fan, although I still don’t have a FaceBook account; I already spend too much time online as it is) have another option: gree.nr. I like a shortener that’s targeted at greens. And, since not many people are using it yet (they just launched), I now have a few short versions that make sense for my own websites:

http://gree.nr/AES
http://gree.nr/CEW
http://gree.nr/FGS
http://gree.nr/TK

I guess I’m a gree.nr cybersquatter.

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Do we really need a quick charging infrastructure for EVs?

A post at New Energy View on Electric Vehicle (EV) economics and charging stations got me thinking about public charging stations and range anxiety again.

I think public rapid charging stations are a wast of time. Like New Energy View, I think personal EVs will be charged up almost exclusively at night, and charging stations need only be there to add a little bit of range to combat range anxiety.

I’ve long thought the best option for public charging would be standard 120V/20A outlets at large retail/grocery stores. At 3.6-3.8 mi/kWh, that’s only enough for an additional mile of range for 7 minutes of charging, but the outlets would be cheap to install (probably no more than $100 each, and would be enough to help a lot with range anxiety.

Suppose you are considering an 80 mile trip in your EV that normally has 75 to 100 miles of range, depending on driving conditions. (This large a range variation is not unusual.) If there were no public charging option, you wouldn’t do it, fearing being stranded. But if you know that there were a few 120V charging stations available near your route, you probably would be willing, since you probably would not need them, but if it looked like you were using up energy faster than normal, you could go grocery shopping while your car was charging, and add the extra 5 miles of range you might need in the time it takes you to run your errand.

Hence five to ten 120V charging stations could do a lot more to combat range anxiety and increase the number of trips taken by EVs a lot more than one quick charge station.

Plus there is an added bonus: e-bikes and electric scooters (which I expect to have much more rapid market penetration than electric cars because of the vastly superior economics) could use these low voltage charging stations to add significantly to their range in relatively short periods of time. While an electric car might only get 3-4 miles per kWh, an e-Bike can get 40-60 miles per kWh, which means an e-Bike will charge at a rate of about 2 miles of range per minute of charging.

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Outdoor Advertising and LEDs: Jevons’ Paradox or Not?

I’ve blogged before about when Jevons’ Paradox applies, and when it does not. When energy consumers are price sensitive, they may respond to increasing efficiency by using more energy services. When they are not price-sensitive, they don’t.

But here is a new twist: increasing efficiency may come bundled with additional features. Those features may lead consumers to use more energy, even if the increasing efficiency alone would not.

In the case of outdoor billboards, the advent of inexpensive LED lighting may not be so much due to increased efficiency over traditional lighting technology, but the result of additional utility. LED bilboards can show animation, and also can show time-sensitive advertisements. These extra features are leading to an increased use of electricity in billboards, even as the technology is becoming more energy efficient… at least in terms of lumens per watt?

Perhaps I’m splitting hairs here, but I think the increased use of energy in outdoor signage using LEDs is due more to the additional services and interactivity that LEDs provide compared to traditional halide lighting (see this article in the Economist). Put simply, when something becomes more useful, people use more of it, not, as Jevon’s paradox would imply, that people use more outdoor signage lighting as it becomes cheaper.

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