LED-based lighting is touted as 'green' lighting and we have made positive note of its use in e-media facilities and other ICT applications. While it is true that Light-Emitting Diodes produce more lumens per watt that either incandescent or florescent technologies, lamp-to-lamp comparisons fall short when LEDs enable massive new energy consumption. A case in point is digital signage, where a single LED-based outdoor billboard can consume more energy than a typical US home.

A study from SCRUB, "the public voice for public space" explains:

…whereas traditional, static signage is illuminated by two or three “inefficient” lamps at nighttime, digital signs are comprised of hundreds, if not thousands, of “green” LED bulbs, each using between 2-10 watts…it is no surprise that overall energy consumption of digital signage exceeds that of static signage, and makes bulb-to-bulb comparisons irrelevant in this context.
Additionally, with all digital display types, the players which control the changeable images and the fans required to cool them must be taken into account, as they too increase energy consumption. Adding auxiliary equipment, such as extenders, further increases the power demand.

This is another example of where increased energy efficiency does not mean reduced energy consumption. The SCRUB goes on to provide data showing that LED billboards can consume 61-323 MWh/year, compared with 11 MWh for an average US home.

The report goes on to note this technology's potential to negate efforts to reduce peak energy consumption:

LED units…cannot function well in heat which reduces the unit's life expectancy. As a result of the tremendous amount of heat generated in LEDs , and the additional impact of hot weather on the signs, an air conditioning unit is incorporated to cool the components. The energy drawn from the grid is highest during the summer months when the heat from the sun coupled with the heat generated by the higher brightness of the LED unit requires increased demand on the air conditioning system installed for cooling the LED unit. This energy use corresponds directly with maximum peak demands…If traditional billboards continue to be replaced by LED signs, the growing draw of energy during peak hours could negate the efforts of Utility companies to reduce demand during peak times.

Finally, SCRUB's report looks at the looming e-waste potential:

Light Emitting Diodes have a lifespan of 100,000 hours…this equates to roughly eleven years for LED billboards, compared to the fifteen years for traditional static billboards. At that point, the diodes will be operating at 50% of their prime brightness…considering the return on investment that the sign owner has received by that time, he or she will likely not hesitate to replace the sign quickly…
LED’s…and digital players and extenders are recyclable, but their de-manufacturing and reuse is not always mandated or monitored.
…Volumetrically, digital signage does generate more waste to be recycled than the paper, vinyl sheets, and plywood or canvas facing of static billboards, but lacks the potentially toxic adhesives.

In the United States, neither the federal government nor most of the states require the recycling of consumer media gear other than CRT displays. There is even fewer regulations covering the disposal of professional media equipment, such as that generated when television stations converted to digital.

USA Today reported in March 2010, "Digital billboards are a fast-growing segment of the outdoor advertising market. Since a federal rule against them was eased in 2007, the number of digital billboards [in America] has more than doubled to about 1,800 of 450,000 total billboards." This gives us less than seven years to figure out how to deal with the impending e-waste problem.