LEDs win top grades

Light-emitting diode (LED) streetlights perform best overall in terms of energy efficiency, lifetime, environmental impact and costs, according to the University of Pittsburgh. The team compared the lifecycle – from extraction of raw materials through fabrication and assembly to electricity consumption during use and finally disposal – of LEDs, high-pressure sodium (HPS) and metal halide lamps and the gas-based induction bulb.

LEDs though the most expensive options for streetlighting, consume only half the electricity of HPS or metal halide installations, last up to five times longer and produce more light. The analysis concurs with critics of LEDs that they do need considerable energy to produce and can be difficult to recycle, but they contain no mercury and fewer toxins such as iodine and lead.

The greatest impact of LEDs, however, comes when electricity consumption during use is considered – which is much more significant than that required for production. LEDs require much less energy than HPS or metal halide lamps.

The potential savings could be huge. The city of Pittsburgh, for example, could save $1 million a year in energy costs and $700,000 in maintenance by replacing HPS lamps with LEDs. That’s no small amount.

Lighting the way

High-intensity discharge (HID) lights used in stadiums, factories, airports and street lights make up a $10 billion global market annually. These are inefficient, says HID Laboratories, which is launching a more efficient smart-lighting platform, called the SmartPod Luminaire. This is built around a ballast, which the company claims reduces HID lights’ energy use by between 31 and 42 percent.

HID Laboratories’ ballast uses electronic circuits and a robotic control algorithm to more tightly control elements like the current and frequency in the lamps. Instead of using a filament, like incandescent bulbs, HIDs have a capsule filled with gas that produces light when hit with an electric current. By smoothing the current and running the lamps at a higher frequency, the controls can get more light out of a lower-wattage bulb.

While conventional HID lights get between 60 and 80 lumens per watt, the SmartPod will deliver 90-103 lumens per watt, the company claims. For comparison, typical incandescent bulbs get 10-20 lumens per watt, fluorescent lights get 70-80 lumens per watt and most LEDs deliver 60-90 lumens per watt.

Three markets with big potential for the SmartPod are industrial manufacturing, commercial warehouses and “ultra-high bay” lighting, which illuminates large spaces with really high ceilings.
Stitching up every hole in the energy pocket helps.

As we had posted earlier, street lights guzzle a lot of energy, and often it is a waste. Smart ways of getting the most out of a gadget without spending too much energy are part of the solutions we seek.

MIT researchers have figured out why concrete breaks down and thanks to the research we could have buildings, bridges, and sidewalks last for hundreds of years!

Creep or the process that create cracks is created when calcium-silicate-hydrates (CSH) rearrange at the nano scale. When mixed with water, CSH particles change in density from 64% to 74%. Now, by adding silica fumes to concrete, overall density can increase to 87% and could eventually lead to lasting, lighter structures.

It could also mean reduction in the need for concrete, and hence, the associated 5-8 percent emissions from concrete constructions could also reduce. Considering that 20 bn tons of concrete is churned out annually, that’s a lot.