Ozone Depletion and Global Warming

A teacher colleague was speaking to me the other day, and she said that many of her students, high school, were confused about the terms and concept of the ozone layer and the carbon dioxide-global warming debate, including mixing up the two. Although they are related, there are separate issues involved.

Let’s take a look at these two issues… The ozone layer debate surfaced in the late 70s as satellite information revealed a large hole in the ozone layer over both of earth’s poles. What is ozone, and what does it do? Ozone is a special form of oxygen, written chemically as O3 . Normal oxygen, the kind we breathe, is shown as O2 . At ground level, ozone is bad news, because it is very reactive and contributes significantly to the formation of smog. Ozone is generated by internal combustion engines and other industrial processes and by lightning. In space, on the outer edge of the atmosphere, however, ozone serves the very useful purpose of protecting the surface of the earth from harmful ultra-violet (UV) rays from the sun. The ozone layer is not very thick, I have read as thin as a few centimetres, but it absorbs these UV rays nicely.

These holes that were found turned out to be caused by the reaction between ozone and chlorofluorocarbons, more commonly known as Freons®. These compounds were used extensively in aerosol propellants, refrigerators and air conditioners and plastic foaming agents, from which they easily escaped into the atmosphere.

In 1987, most countries, including Canada, signed the Montreal Protocol, in which they pledged to drastically reduce the amount of Freons used, and switch, where possible, to less ozone-damaging substitutes. This process has, over the last fifteen years or so, had the desired effect and damage to the ozone layer has been lowered considerably. Although gains have been made we must maintain our efforts.

This was the reason for the increased awareness of the need for sunscreen, especially in northern latitudes.

Now to the carbon dioxide issue, or Global Warming 101. Most of our industrial processes throughout the world, including transportation, power generation, manufacturing, and many others, rely on fuel to keep going, and mostly this fuel is something that is burned. It used to be wood, then (and still) coal, oil, natural gas, and of course gasoline and diesel fuel. Burning these fuels produces carbon dioxide, lots of it, about the same mass as the fuel burned. In pre-industrial times, there was about 200 ppm (parts per million) carbon dioxide in the earth’s atmosphere. It began to increase in the 19 century, shot up in the 20th, until we are currently looking at almost 300 ppm. This may not sound like much, and you and I can go about our daily lives not noticing any difference.

There are several other gases that contribute to the warming process, most of which are by-products of human activity, but carbon dioxide is the largest single contributor.

However, here is where it gets interesting… you know what a greenhouse is: an enclosed structure covered with glass panels. As sunlight passes through the glass, it is reflected back by the plants, wood and dirt within the greenhouse but at a longer wavelength that does not pass back out through the glass. The air inside the greenhouse becomes much warmer… good for the plants. As sunlight passes through the earth’s atmosphere, the higher carbon dioxide level in the atmosphere has the same effect as the glass panels on the greenhouse, preventing a large portion of the sunlight from being reflected out into space, and thereby warming the atmosphere. In February in Ontario, we may think this is a good thing, but we would be wrong. Significant changes in the atmosphere, including the increase in carbon dioxide and the other “greenhouse gases” can have very severe consequences to rainfall, snowfall, glacier formation, sea levels, sea ice thickness and duration to name a few. These in turn have huge consequences for agriculture. We won’t be growing bananas in Brockville any time soon, but if the places where bananas are grown today become deserts or are flooded by seawater, we have a problem. As well, many millions of people live within a few metres of sea level, so any rise will have catastrophic consequences for them as well as us. (Brockville is about 300 ft. above sea level, depending on where you are in the city).

We will take a look at some of these in more detail in another column, but my point today is that the ozone layer depletion problem, while not solved, is well understood and means are being implemented to address it. The global warming problem appears, by all scientific analysis, to be related to increasing carbon dioxide in the atmosphere, but because we seem to be wedded to carbon-based fuels, and with the industrial intensification in China and India, and the denial by many nations, businesses and individuals that there is a genuine problem, no near term lowering of carbon dioxide is likely.

Recent research has shown that the ozone-depleting chemicals, which we know have been significantly reduced in the last two decades, were also major contributors to global warming, so their reduction or elimination has had a very positive effect in countering global warming.

So, ozone and global warming: two different but interconnected problems, two different but interconnected causes, two (at least) different solutions.

CFLs and Other Bulbs - Real Energy Savings

Compact Fluorescent and Other Bulbs…

We have heard a lot lately about compact fluorescent lamps (CFLs), even to the extent that municipalities and governments are considering banning the traditional incandescent bulbs in favour of CFLs. That seems to be rather heavy-handed and may not achieve the desired results, but action is required because lighting amounts to about 20% of our overall electricity consumption.

So let’s take a look at this trend and understand the benefits and drawbacks of these and other types of lighting.

The traditional light bulb, also called the incandescent bulb, is the original invention of Thomas Edison and Joseph Swan, dating from about 125 years ago. It works by passing an electric current through a thin wire filament, usually tungsten, inside an evacuated glass globe. The tungsten glows white-hot, and gives off light. As you can imagine, anything that glows white is pretty hot, and in fact an incandescent bulb only converts about 5% of the energy it consumes into light. The rest is given off as heat. We don’t always want heat along with our light, but up to now we get both like it or not.

The new popularity of compact fluorescent lamps (CFLs) owes a lot to two things: the great improvement in manufacturing leading to much lower cost, and the lower energy consumption. In fact, a CFL will last about 10,000 hrs, compared with about 1000 hrs. for an incandescent bulb, and it converts about 30% of its electrical energy into light. A CFL works by energising a gas inside the coiled glass tube, which causes a coating inside the tube to glow. As well, the new CFLs are brighter, more like natural light, and don’t flicker. Some heat is generated but far less than an incandescent bulb. Downsides are that they cannot be dimmed like an incandescent bulb and CFLs contain a small amount of mercury which is a concern at the time of disposal where the mercury may be released and contribute to air and water pollution.
Some manufacturers such as Philips, the Dutch electronics giant, and GE make very low mercury content CFLs. Safe disposal requires storing the bulbs unbroken until they can be processed. Consumers should seek disposal advice from local authorities, who need to prepare to receive these bulbs. Disposal methods include returning used CFLs to where they were purchased, so the store can recycle them correctly; or taking used CFLs to a recycling facility.
Proper disposal involves crushing the bulbs in a machine that uses specialized equipment and a mercury-absorbing filter to contain and treat the contaminated gases. Such machines are becoming more common along with CFLs. The crushed glass and metal is stored safely in drums, ready for shipping to recycling factories
Here is the real payoff… it is estimated that there are about 400 million incandescent light sockets in Canada. If 85% can be replaced with CFLs, we could save an estimated 15 million tons of carbon dioxide emissions and save nearly two billion dollars in electricity costs. That, readers, is serious conservation.

The real star players in the lighting Olympics are LEDs. LED stands for Light Emitting Diode. These put out an amazing amount of light for their power consumption, converting up to 70% of the electricity to light, and have a lifetime of more than 50,000 hrs. These numbers look pretty attractive, but they are still very expensive by comparison with incandescent and CFLs. You certainly get a lot of light for little electrical power. Work is progressing in making them cheaper, and in a range of “warm white” colours that people demand for home lighting. Philips has several programs underway to develop affordable and flexible LEDs. They are continuing to find many applications in automotive and aerospace, because of their small size, low power consumption and lack of heat generation. Almost daily we see new applications, such as tiny light gadgets for key chains, and convenient and bright flashlights.

If you can, do your part by converting your light bulbs to CFLs and help lower your electrical bill and your carbon dioxide emissions. It may be that the standard incandescent bulb is about to become the oil lamp of the twenty-first century, a useful gadget whose time has passed.