Science Matters with Rod Charlton

Polymer Recycling

noreply@blogger.com (Rod) — Sun, 10 Aug 2008 00:55:00 +0000

An issue that pops up from time to time is related to the recycling of plastics… can it be done, is it economical, how do you do it and what do you get?

Let’s take a look at this subject and see what some of the issues are and what we as consumers can do about them.

First, what is a plastic? Most people understand the word “plastic” to mean something sort of light, flexible, non-rusting and maybe cheap. In the chemical world we use the word polymer, which means “many units”. Polymers are typically made from small molecules containing carbon, which are attached to one another by chemical processes to make very long chains. The chains can have other atoms such as hydrogen, oxygen and nitrogen in them as well. It is the length of these chains, and the way in which they fit with each other that give polymers their interesting and useful properties, such as resistance to water or oxygen or fuels, ability to be formed, coloured, drawn into fibres, extruded into films, act as an electrical insulator and many other applications.

Polymers generally have two main enemies: heat and ultraviolet light (sunlight). This is why your plastic lawn chair goes brittle after about three summers. The heat and UV act to break the long chains into smaller fragments. This weakens the polymer and soon it will fracture or crumble, and the object made from the polymer is no longer useable. Some things can be added to the polymer to protect it from heat and UV, such as carbon black pigment, or special compounds called antioxidants, which will extend its life.

So now we get to the recycling part. We collect water bottles, grocery bags, and margarine and yogurt tubs and put them in the blue box, but what then? All of these will have been exposed to some heat and UV and they will not be as strong as when they were made. As well, by the blue box stage they are all contaminated with labels, adhesive, and of course residue of what they contained. Another issue is that not all polymers are alike in that the items I mentioned above are all made from different polymers that cannot be combined. So, there have to be several processes: separation, cleaning and sorting, and then upgrading of some kind to make them useable.

Now, another part of the problem: many polymers are used in food packaging and medical applications, where contamination of any kind is unacceptable, and some applications such as fibre spinning require a very clean polymer. So you can already see the problem emerging: every time you recycle a polymer, you essentially downgrade a step or two. If you are making plastic municipal garbage cans or park benches, you have a lot of polymer to choose from, at a very reasonable price. Food wrap and intravenous tubing requires top quality material, and as a society we seem to want more food wrap and fewer municipal garbage cans.

Another issue is this: pick up your full blue box (without glass jars in it) and you will see it is pretty light. Waste polymer is mostly air, and until you can crush it or grind it or make it denser it takes up a lot of space for not much material, so shipping costs can be high.

So where does all this take us? Good quality waste polymer is a useful commodity and can command a high price. But it required extensive and costly sorting, cleaning and general upgrading to get there. Lower quality recycled polymer, with more contamination is of considerably less value. Our manufacturing system has incorporated economies of scale such that virgin polymers such as Styrofoam and low density polyethylene are only slightly more expensive than recycled material so there is little incentive to recycle these. PET (water bottle polymer) is of higher value and recycling these is more economical.

The grocery bag you took home from the supermarket the other day weighs about 5 grams. The recycle industry will pay about $.25/lb. for this material… so you need 100 bags to make $.25 worth of polymer for recycling, and only then if you have a truckload of it.

Used tires present a special case. Recycling rubber is already a thriving business, and most truck tires have treads made from recycled rubber. There are several ways to deal with used tires that are proven: they can be shredded and added to new rubber to make new tires and other rubber products; they can be shredded and added to paving material after the steel wire is removed; they can be added to the fuel used to fire a cement kiln, as these are fitted with effluent control; they can be heated in a vessel with a low oxygen atmosphere where the rubber breaks down into an oil-like material that can serve as fuel or be added to a crude stream. These technologies are either commercial in scale or at least proven in trials.

There is a class of polymers made from cellulose, corn waste, sawdust, and other renewable materials that we will look at in a later column.

As consumers we must demand more recycled content in the areas where it makes sense, and do as much as possible to clean, sort and recycle our polymer waste. We can influence the marketplace through our choices and our purchases. Let’s try to make reasoned choices and work to lower the amount of polymer waste we generate.

Carbon - Carbon - Carbon

noreply@blogger.com (Rod) — Fri, 11 Jul 2008 22:32:00 +0000

CARBON – CARBON – CARBON

There is a lot of talk about carbon today… we hear of carbon credits, carbon offsets, carbon caps or limits, carbon sequestering, carbon footprint, and that is just the beginning. These are all related to lowering carbon dioxide in the atmosphere, by technological means or changes in the way we do things or organise our affairs. Let’s take a look at one of these and understand what it means, and what effect it can have.

Carbon offsets are in the news and the public eye, so let’s see what they are about. My wife and I recently went on-line and booked a pair of return air tickets to Calgary; the process was pretty straightforward. Then we came to a question: Did we wish to purchase a carbon offset? Naturally being rather inquisitive, I took a look to see what it was about.

First we have to back up slightly. Remember a few columns back I mentioned that the burning of fossil fuels is the main contributor to the build-up of carbon dioxide in the atmosphere? Carbon offsets are meant to lessen or remove a portion of each individual’s contribution to the carbon dioxide load, by doing or supporting something that removes carbon dioxide from the atmosphere. In Canada, this typically means planting trees. So, Air Canada figures that flying two adults to Calgary and back generates about 1.2 tonnes of carbon dioxide, and that, if we wish to pay it, they will give $19.20 on our behalf to an organisation called Zerofootprint (www.zerofootprint.net) who will plant enough trees to absorb that much carbon dioxide. Zerofootprint’s website has enough detail on carbon offsets to satisfy everyone’s curiosity.

Although there are several issues associated with this approach, it is clearly better to do something than nothing. For example, there is considerable disagreement about how much carbon dioxide is absorbed by a tree growing in Canada vs. a tree in a tropical forest. You may have seen the R and T article on Aug. 14, in which the Ontario Government promises to plant 50 million trees to “soak up” 3.8 million tonnes of carbon dioxide, or 76 kg/tree. Another reference I found indicates 560 kg/tree. As well, we want to ensure that the offset is incremental, that is, they use my $19.20 to plant extra trees, not just buy a truck to haul the trees. How long before those trees soak up the 1.2 tonnes from my trip? Is there enough space where trees can be planted to account for my and other Canadians travel requirements? Can or should we differentiate between essential travel and discretionary travel? I read recently that flying to a tropical island in February so you can lie on the beach may become socially unacceptable as people become more aware of their individual impact on carbon dioxide levels.

Air Canada’s claim of 1.2 tonnes is backed up by solid evidence, as they fly a lot of people to a lot of places, and they have very detailed information regarding fuel use, load factors etc. Air Canada is doing their part to lower their carbon footprint by employing more fuel-efficient aircraft, using weight reducing strategies, and managing their fuel usage more carefully. Some other carbon offsets may be based on more speculative data, but as I mentioned above, it is clearly better to do something than do nothing.

From an industry perspective, there are a lot of strategies in place. Carbon can be traded just like other commodities. If an industry produces X tonnes of carbon dioxide per year, and implements technical and operational changes that lower this to 80% of X, they can then “sell” their 20% saving to someone who is willing to pay, less a small portion that is “retired”, that is, withdrawn from the overall amount of carbon dioxide that is discharged to the atmosphere. The purchasing industry may be winding down, or in the process of updating their process, or struggling with out-of-date equipment, or all of these. The marketplace seems to decide how much a carbon offset is worth, and as more people become aware and concerned about the issue, this value is only going to increase.

As you can tell, right now this process is voluntary, at least at the consumer level, but in the coming years we will likely see guidelines and regulations coming into force, and offsets may be applied to personal transportation and other activities over which we, as individuals, have control.

Carbon offsets are one of many means we have to reduce our carbon footprint, that is, the amount by which each of us, through our everyday activities, adds to the carbon dioxide level in the atmosphere. It will require a concerted effort to by industry and government to make this work, because ordinary people will be very resentful if they are doing their best regarding carbon dioxide reduction yet significant contributors in the public and private sector are being seen as getting away with uncontrolled generation.

Lightning - The Big Strike

noreply@blogger.com (Rod) — Sun, 15 Jun 2008 01:35:00 +0000

The summer thunderstorm season is upon us and it might be helpful to take a look at lightning and understand some of the ways we can protect ourselves.

Lightning is one of nature’s most awesome displays and one of its more dangerous, and most misunderstood. We are in the middle of summer, traditionally the time of powerful thunderstorms that boom and crack and pour, and are gone in a few minutes. Behind they leave cracked and downed trees, power outages and sometimes injured bystanders.

Lightning has a long history with mankind… think of the metaphors usually associated with speed, and the use of lightning bolts as symbols of power.

Let’s take a look at lightning and see what it is about. Lightning is electricity… not exactly what you get when you flip on the light switch, but more like the kind you get when you shuffle across the carpet and touch the doorknob, but hugely amplified. It is estimated that a lightning bolt operates at many millions of volts, and generates temperatures of several thousand degrees. Scientists, including electrical engineers, and meteorologists are not in total agreement on what lightning is, but seem to agree that inside the huge upwelling clouds that typically occur late on a hot summer day, there are very strong currents that move water droplets, dust particles and ice particles rapidly up and down. This process causes the droplets and particles to become either positively or negatively charged, and the clouds will end up with a huge voltage differential between the top and bottom. The charge at the bottom of the cloud, a few hundred metres from the ground, will try to neutralise its charge to the nearest ground, and that will typically be a tall building, an antenna or a tree.

What happens then is a small “leader”, a relatively weak discharge, tracks upward from the ground to the cloud, and the really big strike follows the path created by the leader to the ground. The big flash, the burned and split tree, and the noisy crack then follow.

The rumble of thunder is caused by the bolt superheating a channel of air that surrounds it. The closer the flash and the boom, the closer the actual bolt is to you. One mile per five seconds of delay is the general rule.

Not all lightning is cloud-to-ground; there is what is called “heat lightning” or “sheet lightning” which is cloud-to-cloud discharge, as well as discharges within the same cloud.

The damage caused by lightning can vary greatly. We hear of many cattle being killed by a single strike, yet people have survived strikes with little more than some minor burns. Huge trees may be split from top to bottom, others lose a few branches. A chain may be fused into a single piece, and a fine necklace may leave only a small burn mark.

The old wives’ tale about lightning never striking twice is just that – an old wives tale. The Empire State Building in New York City is struck about 25 times per year. One unlucky park ranger in the US has been struck seven times, and is still around to talk about it!

According to Environment Canada, lightning kills about six Canadians per year and injures about 75, as well as causing numerous forest fires. Windsor seems to be the “Lightning Capital of Canada”, with up to 250 strikes per year in the city. Ottawa records about 90.

There are a number of things you can do to protect yourself in the event you or your group are caught in a storm where there may be lightning. The first thing is to have a plan as to where to shelter, and assign someone to monitor the weather and report any approaching storm. Under a tree is not a good place to seek shelter, but inside a sturdy building, an automobile or bus is generally safe. Open vehicles such as a golf cart or an ATV are not safe, as it is the steel bodywork that protects you. Do not use a telephone, the water taps, and turn off the TV. If you are caught outside, try to find a low-lying area such as a ditch or hollow. You’ll be wet but safe. Crouch down, and if you are part of a group, separate yourselves. Make sure you remove your I-Pod and any earphones you are wearing, and turn off your cell phone. There is no evidence to suggest that I-Pods or cell phones “attract” lightning, but wiring and metallic objects can act as a pathway. Stay well away from steel fences and antennas. Golfers should not wave their 9-iron angrily in the air, and most courses will call golfers in if a lightning storm is approaching.

One interesting product of lightning strikes is something called a fulgurite (fulgur is the Latin word for lightning). A fulgurite is a tube of fused and melted sand formed by the heat of a lightning strike, and it looks like a gnarled branch, varying in length from a few centimetres to several metres, with a coloured glassy interior. They are typically found on beaches and in deserts. In what has got to be one of the world’s worst jobs, people in Florida pound steel rods into the sand at the beach when a lightning storm is approaching, then hope for a strike which will form a fulgurite, which can then be dug up and sold.

Lightning is one of Nature’s most dramatic displays, but you can lessen your danger by using a few simple steps and some common sense to protect yourself.

Organic - Or Not?

noreply@blogger.com (Rod) — Sun, 18 May 2008 01:02:00 +0000

ORGANIC – OR NOT?

The growing presence of and demand for organic food, in the form of produce, meat, dairy and even processed foods, is causing consumers some difficulties in understanding what the designation means and what they are getting for their money.
Let’s take a look at this as it applies to produce and try to understand some of these issues.

To start with, in the chemical world, organic means any compound containing carbon, regardless of its origin. As applied to food, if you were to ask a non-technical person, they might say that it means a food has more nutritional value, that it contains less pesticide residue, or that its production is better for the environment. All of these are at best only partly true, and often wrong.

Our local supermarkets have sections labelled “Certified Organic”, and our first reaction is that the produce sometimes doesn’t look as good as in the other section, and is often priced higher. First, let’s look at certification. Some producers call themselves organic without any form of verification. Others prefer to be audited, and earn the right to call themselves organic, by a body such as the OCPP (Organic Crop Producers and Processors), the FVO (Farm Verified Organic), or the CCOF (California Certified Organic Farm). At our local supermarket you will find designations such as QAI, ECO Certified, IMO Control, and USDA Organic. As you can see there are many qualifying organisations and sorting them out requires some research. To qualify for these designations, producers have to meet a set of standards related to pest (insect and weed) management, fertilizer use, irrigation and runoff management to name a few. The Canadian Government has a set of voluntary guidelines to which producers can adhere, but there is no current inspection mechanism.

A small example: the IMO Control program states that produce may be fertilised with manure or compost up to 120 days before harvest, that the manure must have a specific carbon to nitrogen ratio and be maintained at a certain temperature for 3 days prior to application. So you can see that the regulations can be very specific.

Our local supermarket reports that there is a small but growing demand for organic produce. The problems are that it tends to have a shorter shelf life, and therefore there is more waste, and the selection of items available is quite varied. These issues make it more expensive to carry. It is usually sourced from a warehouse in Ottawa, and as a consumer you can ask for locally grown produce.

Regarding nutritional value, there is no scientific evidence, despite numerous studies, to confirm that organic produce is nutritionally superior to that grown by conventional means. Organic growers will choose varieties of produce that are naturally pest-resistant, so there may be less pesticide residue on the harvested product. I say less because there is no way to control what is in the air or water that may end up on the produce, and conventional farming methods usually require that pesticides use is curtailed well before harvest. Having said that, no study has associated any known health effect with pesticide residue, and the overall benefit of eating fresh produce far outweighs any perceived harm. Taste is another matter, and many consumers report that organic produce tastes better. This may be a perception issue, or it may be related to the fact that the produce is generally fresher.

As far as farming practices are concerned, it is a mixed bag. Some organic farmers are using well water instead of surface water (streams or rivers) because the surface water may be contaminated with agricultural run-off from upstream. Fertilizing organic farms with cattle manure is acceptable, but run-off must be controlled and trucking organic manure many kilometres seems to defeat the spirit of the “small footprint” philosophy, even though it meets the letter. Organic farming is typically less efficient from a land use standpoint as well, in that productivity of an organic farm is about 75 – 80% of a non-organic farm. Rows have to be further apart, there may be a greater loss due to insects or birds, and hand-weeding is labour-intensive.

Then we get to the sustainability part. Another goal of organic producers and consumers is to grow produce in a sustainable way that uses less fossil fuels and chemicals in the overall process, and is less damaging to the land in the widest sense. Do we clear more forests for farmland because organic farming takes more area to produce the same yield? Does it make sense to grow organic potatoes in California then truck them many thousands of kilometres? Should we forgo asparagus in January so that we only ship and eat locally? Is it OK to store apples in coolers with a carbon dioxide atmosphere so we can have apples year round? The designation “organic” does not address these sustainability issues, yet as consumers we should be asking ourselves these questions.

Some people have reported a lessening or disappearance of some allergic symptoms when they switch to organic food products, but personal anecdotes do not constitute a controlled scientific study.

What can an individual do? Buying locally, from producers who ship their products a few to a few hundred kilometres, is probably a good start. Asking those producers how they grow their crops will help the consumer understand the complexity of the issue. Some farmers markets are “going organic” with only certified produce being sold. Overall the health benefit of consuming a variety of fresh fruits and vegetables from all sources is well proven.

Ozone Depletion and Global Warming

noreply@blogger.com (Rod) — Mon, 28 Apr 2008 13:30:00 +0000

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

noreply@blogger.com (Rod) — Fri, 11 Apr 2008 01:19:00 +0000

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.

Lead in Drinking Water

noreply@blogger.com (Rod) — Fri, 21 Mar 2008 22:28:00 +0000

Lead in Drinking Water – A Discussion

We saw the news items recently that indicated that the Government of Ontario is concerned that the levels of lead in municipal water supplies are higher than the Provincial standards, and they have requested that about thirty municipalities across the province test the water in peoples’ homes.

There have been several articles in the Recorder and Times and numerous other papers regarding this, and I thought it would be appropriate to take a more detailed look at the issue and understand some of the background of the issue.

Lead has been around for a very long time, and has a history of use to man for millennia. In the twentieth century physicians began to realise that extensive exposure to lead caused neurological impairment (brain damage) to young children and was particularly dangerous to pregnant women. Human exposures through handling metallic lead such as fishing weights or working with stained glass are of no great concern. Our concerns are areas in which lead can be readily ingested, and this occurs in inhaling or breathing lead-containing dust, children chewing on lead-based paints, and of course, through food and drinking water. Since the elimination of lead additives to gasoline nearly twenty years ago, and the discontinuing of lead-based pigments in consumer paints, the first two are not significant contributors for most Canadians. This brings us to food and drinking water.

Lead levels in food are very strictly controlled and are generally at or below the limits of detection by modern analytical techniques. The levels in drinking water are set by the Ontario Government at 10 micrograms per litre. To put this in perspective, this represents about one-half of a BB pellet dissolved in a typical backyard swimming pool. The water entering the St. Lawrence is monitored at Wolfe Island, near Kingston, and the typical level seen there is 0.016 micrograms per litre, or about one five-hundredth of the allowable amount.

So if lead is so low coming into the Brockville water supply, where does it come from? Up until the early 1950s, lead pipes were in common use for water supply lines. They were easy to install, join, repair, bend, and the lead did not give a taste to the water. However, as the toxic effects of lead were understood, its use in drinking water pipes was discontinued and indeed Brockville has reviewed its use of lead and has determined that lead was not used for water distribution. However, there may be some homes primarily south of the railroad tracks where the line from the supply main to the house is still lead.

Now we get to the chemistry part… the inside of water supply lines typically becomes coated with scale, deposits of calcium and magnesium, and these deposits lessen the amount of lead which can dissolve in the water. Lead is less soluble in cold water than hot, so use cold for your cooking and drinking. As well, lead has a pH point (pH is a measure of acidity we will discuss in a future column) where it is minimally soluble in water, which is pH 7.6, and it happens that Brockville City water is pH 7.6 So what this all means is that we are lucky that the water chemistry works in our favour and we are not at great risk here.

Having said that, there are a couple of additional points to consider. Most homes built in the past fifty years or so used copper plumbing that was soldered together. Lead was a component of solder until the late 1980s. The amount of lead that dissolves from solder into water is thought to be very small, because of the low area exposed to the water, and we already learned that the chemistry is on our side.

If you live south of the tracks, and if you suspect that you have a lead connection, the recommended practice is to flush the toilet or run the shower before taking water that had been sitting overnight from the tap; this is something most of us would do anyway. Tests have been carried out in twenty houses in Brockville; all were within the Provincial standards and all but one were below 3 micrograms per litre.

The issue of lead in well water in Leeds-Grenville is more complicated, as our area includes limestone, Canadian Shield granite, and sedimentary soil, and each has its unique chemistry. The best information seems to be that there is very little lead in groundwater in Eastern Ontario. Go to the Health Unit website, www.healthunit.org/water/infosheet/aquainted.htm and www.healthunit.org/water/test/lead.htm to find out more about maintaining your well in good condition, and about lead testing and availability.

If you travel to Central and South America and bring back a highly-coloured piece of glazed pottery, use it for decoration only. Coloured glazes are often made from lead, cadmium and chromium, which make wonderful colours but are all very toxic. Many of our favourite beverages, such as fruit juices and wines, are very acidic (they have a low pH) and will extract the toxic metal from the glaze.

So use caution in your exposure to lead, run your taps, use cold water for cooking and drinking, and if you are really concerned, ask for a test.

Hydrogen as Automotive Fuel

noreply@blogger.com (Rod) — Sat, 08 Mar 2008 01:02:00 +0000

Many of us have been told, and have figured out that about the only fuel that doesn’t give off carbon dioxide as it burns is hydrogen. So it would make a great fuel for a motor vehicle, right? Well, as with everything, it is a good news/bad news story.

Hydrogen does indeed burn nicely, giving off water vapour and heat. Most current internal combustion engines can burn hydrogen with relatively minor modifications to the carburetor, and there would be no need for a catalytic converter. However, there are two big issues about hydrogen: how do you make it, and how do you store it?

Almost all industrial-scale hydrogen is currently made from natural gas, or methane. This process generates carbon dioxide as well as hydrogen. If we are thinking about hydrogen as a motor fuel, we will need more methane than is currently available, and we will generate a lot of carbon dioxide. So… how else can you make hydrogen? You can pass electricity through water, and you get hydrogen and oxygen, lots of both. But you had better have your own generating plant, because you will need a lot of really cheap electricity. You don’t really want to burn anything to make your electricity, such as coal, oil, or natural gas, as you will make more carbon dioxide, so you are stuck with hydro and nuclear, our current favourites, or perhaps wind, solar, or tidal electricity, none of which gives enough power, at current generation efficiencies, to do the job. Fusion power is several years in the future at least. Seeing as we have dammed most of the rivers that are suitable, we are looking at nuclear – generated electricity as the most practical option. I know nuclear – generated electricity is like a red flag to a bull to many members of our community, but let cool heads prevail and let’s discuss it in reasonable terms (in another column).

After you have made your hydrogen you need to be able to carry enough in your vehicle to give about 400 – 500 km. driving. The current methods include a large high pressure (200 to 350 atmospheres, an atmosphere is about 15 psi) tank, weighing up to hundreds of kilograms, or a lower pressure tank (10 to 100 atmospheres) containing metal hydrides, which store hydrogen like a sponge, and give it up with gentle heating. GM, Toyota and Honda are all researching various promising hydride technologies. Both of these storage systems are going to fill the trunk of a standard car or mini-van. Another method of hydrogen storage is as a cryogenic (very very cold) liquid. This gives a greater energy density, but at the expense of having to cool and compress the hydrogen to begin with, then having to insulate the tank, which would be at about -250°C. Another issue would be filling your tank, not simply a matter of sticking a nozzle in a trapdoor in your rear fender as we are accustomed to doing. As technologies emerge, the infrastructure will need to be put in place to make hydrogen motor fuel available in the right form, requiring huge investments by supplying companies. Governor Schwarzenegger of California and Premier Campbell of British Columbia have just committed to a “hydrogen highway” from Los Angeles to Vancouver, with hydrogen fuel available along the Pacific Coast. There is also the huge psychological obstacle I’ll call the Hindenburg Factor – remember the German dirigible which crashed and burned spectacularly in 1937 (or the movie of the same name in 1975) and many people will say “No way!”. Having said that, the hydrogen industry as it exists today has an excellent safety record.

Despite these rather daunting technical challenges, several automobile manufacturers are going ahead with hydrogen-fuelled vehicles. BMW plans to introduce the Hydrogen 7, which will incorporate an internal combustion engine capable of running on gasoline for 500 km., or hydrogen for 200 km. Ford is marketing the “Edge”, a crossover SUV that is powered by plug-in hybrid fuel cell system that runs on hydrogen in a high pressure tank and goes 325 km between fill-ups. Not sure where they will fill it up in Brockville for a while yet.

One of the more promising areas where hydrogen-fuelled vehicles will be the right choice is urban transit. Buses work in a clearly-defined radius, they return to a central location where specialised fuelling can be set up, they work in cities where air quality can be a serious issue, and they are large enough to have room for special storage tanks.

So where does all this leave us? It is easy to say that hydrogen is the fuel of the future, and is pollution-free, and indeed it looks great on the surface. But as we can see, there are many issues and technological hurdles to be overcome before we can bid the gasoline and diesel internal combustion engines goodbye.

Ethanol as Automotive Fuel

noreply@blogger.com (Rod) — Fri, 22 Feb 2008 20:40:00 +0000

Remember in the last column we spoke about ethanol and how it is made. Today I would like to explore the role of ethanol in automotive fuel.

First, let’s take a quick look at gasoline. Gasoline, as with most fuels, is a hydrocarbon. That means that its molecules are made up of carbon atoms and hydrogen atoms, with the carbon atoms forming either a straight chain or a branched chain. Hydrocarbons make good fuels because they burn easily in the presence of air. You are already familiar with natural gas, a one-carbon hydrocarbon, with a simple formula of CH4, and called methane. Propane, the common barbecue fuel, is three carbons long, so its formula is C3H8. Methane is a gas at room temperature, and propane is a gas but becomes liquid when compressed. By the time we get to 6 carbons atoms, the hydrocarbons are liquids, and become solids above about 14 carbons… wax! So, gasoline is typically about 8 carbons. I say typically because gasoline is not a single compound, but a range of very similar chemical compounds that have a specific boiling point, or that boils over a narrow temperature range.

So, when gasoline and air are introduced into an internal combustion engine, compressed and ignited, the mixture burns very rapidly, and the resulting displacement of the piston in the cylinder turns the crankshaft and thus the wheels. However, we do not live in a perfect world. There is never quite enough air mixed with the fuel to burn everything, so as well as the carbon dioxide, we get carbon monoxide and some chemical fragments of the gasoline molecules that form soot and other compounds. If we add something to the gasoline that has oxygen in it, such as ethanol, (remember the formula for ethanol is C2H5OH) we can achieve a better and more complete combustion. Nevertheless we are still stuck with carbon monoxide and dioxide, serious greenhouse gases.

There is a downside, of course. The oxygen in the ethanol molecule means that weight for weight it doesn’t have the bang that gasoline has, so there is a fuel mileage penalty, estimated at up to 10%, but a cleaner exhaust. The trick is to add enough ethanol that the exhaust quality improves, but not too much to upset the fuel injectors and the internals of the engine management system. If you look at most pumps around Brockville, you will see a sticker saying “may contain up to 10% ethanol”. This level can be tolerated by most modern vehicles without modification. If we want to run higher levels of ethanol, we have to make sure our vehicle is equipped to handle the additional ethanol.

There is a current oxygen-containing additive called MTBE (we’ll skip the formula for now) which serves the purpose of providing extra oxygen, but there are issues around its safety and it is made from crude oil, whereas we know where we can get ethanol.

Some of you may be familiar with the situation in Brazil. There is little natural petroleum in Brazil, but a huge quantity of sugarcane and low cost labour. Therefore ethanol derived from sugarcane forms a large part of the Brazilian motor fuel supply, and all vehicles sold in Brazil are designed to use this fuel. As well, there would be operational problems using pure ethanol as a fuel in our winter conditions, something the Brazilians do not have to consider.

So, using ethanol as a fuel additive or substitute will have a beneficial effect upon emissions, and will reduce our reliance on crude oil, but it is not the magic cure that some have promised. The latest estimates, and they are only estimates, indicate that the substitution of a major portion of our gasoline with ethanol may result in a reduction of the transportation component of greenhouse gases of up to 25 – 40%. Another issue is that a major new market for ethanol will benefit farmers but may drive up the cost of chicken, beef, and other foods for which the corn from which ethanol is made is a food source or raw material.

There is also controversy around the overall energy balance of ethanol – that is, how much energy in diesel fuel, fertilisers, etc. does it take to make a kilogram of ethanol from corn, vs. how much energy it gives to the gasoline. I have seen estimates from 50% to 150%. It is easy to see how anyone with a vested interest can make the data look favourable for their cause.

The only fuel that can play a really significant role in reducing greenhouse gases is hydrogen, and we will look at that in a future column.

Science Matters... Ethanol

noreply@blogger.com (Rod) — Wed, 13 Feb 2008 15:09:00 +0000

There are many complicated issues facing the public these days, ranging from waste disposal, recycling, air and water emissions, energy generation and consumption, transportation, and many others. These issues have at their core some elements of science, whether it is chemistry, physics, biology, engineering, statistics, or some combination of these. With your help, I would like to explore some of these issues and examine the science in more detail and together we can understand what is going on, what we are being told, whether it makes scientific sense, and perhaps make a slightly better judgement about the issue. I hope to use my contacts and experience in the scientific community to assist you, the readers, in understanding these issues. I welcome your input.

Our area is about to benefit from the construction and operation of an ethanol plant, and I thought it might be appropriate to look at some of the chemistry of ethanol and try to understand what it is, what it does (as a fuel additive) and what are the pros and cons.

Most of us are familiar with ethanol in the form of alcoholic beverages: wine, beer and distilled spirits. It is suggested that the manufacture of alcoholic beverages counts as the first chemical industry, dating back thousands of years. The ethanol we drink is diluted, with water, fruit extracts and flavourings, to about 5% in beer, about 12% in wine, and about 40% in distilled spirits.

Ethanol, or ethyl alcohol as it is known in chemistry, is a clear colourless flammable liquid, completely miscible (mixes with) water in all proportions. It is the second in a chain of alcohols, because of the two carbon atoms, the first being methanol. The chemical formula is C2H5OH, with the OH group giving the characteristics of an alcohol.

The first and still most important way of making ethanol is via fermentation of sugar or starch. Grapes were among the first fruits to be fermented because grapes are naturally sweet, the enzyme that produces ethanol is found on grape skins, and ethanol production is very simple, and takes place at room temperature, especially if your room is in the Mediterranean basin. Many fruits, vegetables and grains have been fermented in pretty much the same way to arrive at ethanol with many flavours, but the basic chemistry remains the same.

When you are making beer and wine, you allow the fermentation to proceed to a specific point then you stop it chemically, filter or decant your product, and depending on your patience, let it mellow a little before drinking. Because the enzymes that do the work are killed off when the ethanol concentration is above about 15%, no wine or beer is naturally stronger than this.

If you are making spirits (such as rum, rye, vodka etc.) or industrial ethanol, you must distil your mixture. Because ethanol boils at a lower temperature than water, if the fermentation mixture is heated above the boiling point of ethanol (78°C) but below 100°C the ethanol will boil and can be captured by cooling the vapour, giving pure ethanol.

So, our plant in Johnstown will be taking corn, the same corn we feed to cattle and other animals, and fermenting it, then distilling it on a large scale.

Here is what is happening, shown another way:

C6H12O6 --> 2 CO2 + 2 C2H5OH
glucose carbon dioxide ethanol

This is how we show a reaction in chemistry, and it isn’t really complicated. Glucose is the simplest sugar. What is really interesting is that for every kilogram of ethanol produced, we get, free and for nothing, 0.95 kilograms of carbon dioxide. So far, no-one has said anything about the carbon dioxide by-product of fermentation.

Another issue with ethanol is this: Right now all the fermentation technology relies on acting on the fruit or the seed grain portion of the plant material, because that is where the sugar or starch is concentrated. As anyone who has shucked corn knows, there is a pile of the corn plant that is wasted. If we can figure our how to convert that waste material, mostly cellulose, into ethanol, we will have some real progress. Thankfully, an Ottawa company called IOGEN has developed a process to do exactly that, and when it is commercialised (it is currently in the pilot-plant stage) then ethanol may become a significant player in the alternate fuel debate.

As we currently stand, the energy balance, that is, the amount of energy you have to put into making ethanol vs. the amount of energy you get out is subject to considerable controversy. We will take a look at this later.

Now, ethanol may have significant benefits with respect to automotive emissions, and reducing our reliance on fossil fuels, but as you can see it certainly doesn’t get us off the hook with respect to carbon dioxide, one of the main greenhouse gases.

Next week we will take a look at what ethanol does when it is mixed with gasoline and diesel fuel.