Under the Reference Scenario, LED lighting is projected to achieve a market share of 84% of lumen-hour
sales in the general illumination market by 2030, reducing lighting energy consumption in that year alone by 40%, for a savings of 3.0 quads (261 terawatt-hours) - worth over $26 billion at today's energy prices and equivalent to the total energy consumed by nearly 24 million U.S.
Department of Energy estimates it will represent 48 percent of total lumen-hour
sales by 2020 and 84 percent by 2030.
lighting energy consumption nearly in half (46 percent), and forecasts that the use of LEDs in such applications will mushroom over the next two decades, accounting for just over one-third all lumen-hour
sales by 2020 and nearly three-fourths by 2030.
"A tallow candle in 1800 cost roughly $0.40 per 1,000 lumen-hours
," Johnson writes, "while in 1992, a fluorescent lamp cost $0.001 per 1,000 lumen-hours
for the same amount of light.