Ask the Green Architect: Mercury in Lightbulbs

Ask the Green Architect: Mercury in Lightbulbs

Eric Corey Freed is principal of organicARCHITECT and teaches Sustainable Design at the Academy of Art University in San Francisco and University of California Berkeley. He is on the boards of Architects, Designers & Planners for Social Responsibility, Green Home Guide and West Coast Green. This article has been excerpted from his upcoming book, "Green Building for Dummies" to be released in September 2007.

Q: While everyone seems to be pushing the use of fluorescent bulbs, no one seems to be talking about how they contain mercury. Are there any alternatives?

A: You bring up an excellent point about fluorescent bulbs and their mercury content. Let's explore some of the issues:

CFL bulbs: Compact fluorescent (CFL) bulbs are a type of fluorescent lamp that fits into a standard light bulb socket. Initially introduced in the 1980's, CFL bulbs have surged in popularity in recent years. This is due in part due to heightened awareness about the climate crisis, and the surging costs of energy, increasing an average of 40 percent nationally in the past two years.

Traditional bulbs: CFL's are an energy efficient alternative to incandescent bulbs, also known as the traditional bulbs you are most likely accustomed to seeing. The incandescent bulb has changed relatively little since Thomas Edison first discovered a long lasting filament material in 1880.

Approximately 95 percent of the energy consumed by an incandescent bulb is emitted as heat, the rest given off as light. This horribly backwards inefficiency is the main issue in using incandescent bulbs. With only a five percent effective use of energy, they waste an inordinate amount of power.

In commercial spaces, incandescent bulbs pose additional problems. The added heat generated by their use results in the need of more air conditioning, and therefore more energy. In addition, the bulbs are incredibly fragile and short-lived, lasting only 750-1000 hours of use.

Because of the issues surrounding incandescent bulbs, several countries have attempted to phase out their use. Cuba, Venezuela and Australia have all tried to ban their use, albeit unsuccessfully.

The Benefits of Fluorescents

Replacing incandescent bulbs with compact fluorescents saves energy as you are replacing a 100-watt bulb with one that is only 23-watts, while still producing the same amount of light. In addition, the CFL bulbs produce 70 percent less heat, lowering the need for air conditioning. A CFL bulb will typically last ten times as long as a traditional incandescent bulb, saving you $30 or more over the life of each bulb.

If every American home replaced just one light bulb with a CFL bulb, we would save enough energy to light more than 2.5 million homes for a year and prevent greenhouse gases equivalent to the emissions of nearly 800,000 cars.

By swapping all of the bulbs of the world with CFL's would cut world energy use by 10 percent. To put it into perspective, that equals more energy than is currently planned to be saved with solar and wind power.

Reducing energy use also cuts down on power plant emissions of mercury and other emissions that contribute to global climate change, acid rain and smog.

How the Technology Works

Nikola Tesla first introduced fluorescent bulbs at the World Columbian Exposition in Chicago in 1893. They work by passing an arc of electricity through mercury vapor in the lamp. The charged mercury atoms produce an ultraviolet (UV) light, which is absorbed by the phosphor powder coating on the inside of the tube. When energized these phosphors emit the white light you see.

To generate the mercury vapor, a small drop of liquid mercury lives inside the tube. This mercury is instantly vaporized when the lamp is turned on, only to re-condense when the lamp is turned off.

Unlike an incandescent bulb, the fluorescent bulb has no filament to break or get hot. This is what gives the CFL is energy efficiency.

Without the mercury vapor, there would be no light emitting from the tube.

The Problem with Mercury

A four-foot fluorescent tube has an average rated life of at least 20,000 hours. To achieve this long life, lamps must contain a specific quantity of mercury. The amount of mercury required is very small, typically measured in milligrams, and varies by manufacturer.

Mercury is a potent neurotoxin with the potential to build up in the food chain. Even the small amount of mercury in the bulb is harmful to our health.

Autism rates have skyrocketed in the past decade. The U.S. Center for Disease Control now estimates one in 150 children now suffer with autism. Since 1990, there has been a 10-fold increase in the incidence of autism. They are citing mercury poisoning as the leading cause of this alarming rise.

Mercury has been linked to numerous other health problems, including endocrine disruption and cardiovascular disease. It only takes 1/70th of a teaspoon of mercury to contaminate a 20-acre body of water and make all fish within it toxic to humans. This is about the amount of mercury in a typical medical thermometer.

Currently, 38 states have fishery advisories for high mercury levels on one or more bodies of water-meaning that the fish might be unsafe to eat.

The Real Question

Your real question is: Which is worse, to use an incandescent bulb, which indirectly spreads mercury by using electricity, or to use a fluorescent bulb, which directly spreads mercury when we throw it away?

The short answer: continuing use of the wasteful incandescent bulbs is much worse. The long answer factors in using low mercury bulbs, safe disposal of the bulbs, and other technologies.

Several manufacturers now offer low mercury content bulbs. Philips' ALTO bulbs offer mercury content only 13 to 25 percent of typical fluorescent bulbs. This reduction was achieved with no sacrifice in longevity or performance.

Other manufacturers of low mercury fluorescent bulbs: Common Objections

Sustainability issues aside, some common complaints continue to arise regarding CFL bulbs.

Color: Many people feel the light cast by a CFL bulb is ugly. Casting a yellow and blue tint, fluorescent bulbs are responsible for that icky appearance of your face in truck stop bathroom mirrors. Most CFL bulbs are color corrected to now compensate for this and special color bulbs are available. Mixing and matching bulbs from different manufacturers can also create color issues. This presents a challenge if you are slowly upgrading the bulbs one-at-a-time as they burn out.

Dimming: Many people complain CFL bulbs cannot be dimmed, preventing millions of people from setting a romantic mood. Greenlite now sells a color-corrected and dimmable CFL bulb.

Cost: Despite the obvious energy savings and long life of the CFL bulb, many people still feel they are too expensive. In reality, you are losing money for every incandescent bulb you do not replace with a CFL.

Theft: Lastly, building owners, hotel operators and office managers complain about people stealing the CFL bulbs right out of the fixtures. There is no easy way around this, and it is a real issue. Hey, these bulbs are popular!

Disposal Issues

While offering tremendous environmental advantages through energy savings, the disposal of used fluorescent lighting raises some serious environmental concerns.

Several states now regulate the disposal of mercury-containing lamps. The store where you purchased the bulbs should be able to help you recycle burnt out bulbs.

If not, the bulbs can be disposed of through local household hazardous waste collection programs.

Household users are typically exempt from these special disposal requirements. Regardless of the rules, never throw a CFL bulb away into the trash. Recycling opportunities are available in many towns and cities, either at local recycling centers or transfer stations. Contact your local waste disposal officials for details.

Some additional recycling sources:
LampRecycle.org: Lamprecycle.org is a resource for information on recycling spent CFL bulbs.

Mercury Waste Solutions provides prepaid shipping containers for the safe collection and shipping of fluorescent tubes, batteries, and other mercury containing objects for recycling. They claim to be able to recover 99.99 percent of the mercury with their processing of the waste.

Other Sources of Mercury in Buildings

Fluorescent lamps are not the only mercury-containing products we use. A number of building systems contain it. Switches and thermostats in heating and cooling systems; measurement devices, valves, and flow switches in systems that move, store, meter, or regulate liquids; and fire suppression and security systems-often incorporate mercury.

For many of these, mercury-free alternatives are available, generally with no additional cost.

Alternatives to Fluorescent Bulbs

Mercury-free fluorescent lamps are available using xenon; however, their efficiency is about 30 percent of that of a mercury-based fluorescent lamp. The energy consumed would ultimately produce more mercury that simply sticking with a low-mercury fluorescent.

Ceramic metal halide (CMH) offers an energy efficient alternative to those people obsessed with the color of the light from the bulbs. While not as efficient at a CFL, it might be a good choice for color critical, commercial applications.

A light-emitting diode (LED) is a tiny semiconductor that emits light. It looks like a small bulb, but contains no filament. Because of their size and low output, dozens of these LEDs are arranged to create enough light.

Although LED's are twice as energy efficient as incandescent bulbs, they are still not as high as fluorescents. LEDs have an incredibly long life, some 30,000 to 50,000 hours. Currently, the costs are still to high for many uses.

As LED technology increases in energy efficiency and decreases in cost, you will see LED bulbs become very commonplace. It is important to note LEDs are the only non-incandescent light source that does not rely on mercury vapor.

Conclusions

Ironically, CFLs present an opportunity to prevent mercury from entering our air, where it most affects our health. The highest source of mercury in our air comes from burning fossil fuels such as coal, the largest source (54 percent) of electricity in the United States.

A CFL uses 75 percent less energy than an incandescent light bulb and lasts at least ten times longer. A power plant will emit 10mg of mercury to produce the electricity to run an incandescent bulb compared to only 2.4mg of mercury to run a CFL for the same time.

Safe disposal, combined with purchase of low mercury bulbs makes continued use of compact fluorescents a very wise choice.

Remember, saving energy prevents pollution. When you use less energy at home, you lessen greenhouse gas emissions in our atmosphere. Every CFL can prevent more than 450 pounds of emissions from a power plant over its lifetime.

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