Dr Peter Seligman #2: How to cut your greenhouse gas emissions
How to cut your greenhouse emissions
You may not be aware of it but you can make major energy savings at home and in the office and without going to any real expense to do so. Nor do you have to make any compromises in day-to-day comfort. All you have to do is be aware of what all your appliances actually consume and then take appropriate action.
by Peter Seligman, PhD (Bionic Ear engineer, Cochlear and Monash University, Melbourne, Australia).
[NB We have yet to get the GRAPHICS sorted out but the TEXT is presented here initially as a very useful contribution to public education on this issue; please see Dr Peter Seligman's power-point lecture #1: "The Bang for Buck Approach to CO2 Abatement" on the Yarra Valley Climate Action Group website: http://sites.google.com/site/yarravalleyclimateactiongroup/dr-peter-seligman-the-bang-for-buck-approach-to-co2-abatement ].
We are all told – increasingly often – to turn things off, use less energy, use energy efficient appliances. But it helps to understand how much appliances and activities use, to know what to concentrate on. To give an example, it makes no sense to turn off just a lamp in a room where an electric heater has been left on. The power used by the lamp is 100 watts while the heater draws 2000 watts.
Before we start, let’s pick a familiar energy-using object as a yardstick, say the 100-watt light globe.
How big a yardstick is 100 watts anyway? Let’s assume that a globe is on every night for six hours. That’s about 2200 hours a year. So to work out the amount of energy used over that year, all we have to do is multiply hours by watts to get the energy in a unit called watt-hours: 2200 x 100 = 220,000 watt-hours. To make it more manageable, we divide that figure by one thousand to get 220 kilowatt-hours, abbreviated to 220kWh.
To many people, a number like 220kWh doesn’t mean much – so let’s convert it into something familiar– say litres of petrol - energy equivalent. A litre of petrol contains about 10kWh of energy. A kWh is 3600000 watt-seconds which is 3.6 megajoules (3.6MJ; joule is a watt-second).
An unfortunate consequence of the laws of thermodynamics is that the process of producing electricity by burning fuels is not very efficient. The best that can be achieved by burning brown coal to generate electricity is 25%. So four times as much energy is used to deliver what ultimately comes through your electricity meter box and power points. So 4 x 220kWh of fuel to produce that electricity = 880kWh. Translated into litres of petrol that comes out to 880 / 10 = 88 litres – enough for the average car to drive 880km or from Melbourne to Sydney. Surprising isn’t it? That’s just to run one 100W light globe each night for a year.
Black coal electricity generation is much more efficient – about 30%. So the figures for other states are 660kWh and 66 litres etc. A seemingly insignificant light globe used every day goes through a lot of fuel (and energy) over a year.
Another way of looking at this is the amount of carbon dioxide (CO2) that is produced to run the light globe compared to the CO2 produced by a car being driven a certain distance. Because coal produces more CO2 for the same energy than liquid fuels, the equivalent distance for the light globe is over a 1000 km. (see box).
Ready for another surprise? You turn on the taps and jump into the shower. I won’t go into the issue of how long you might stay in there but let’s look at how many light-globe equivalents of power is used while the shower is running. If we are talking about an electric hot water service, these are generally heated at night over a period of about six hours – well slightly less because they build in a safety factor to take into account very cold weather – let’s say five hours. The normal heating element in an electric hot water service is about 4,800 watts (4.8kW). Translating that into 100W units – that’s 4800/100 = 48 light globes. Now let’s look at how quickly that water could be used. How long would it take to drain your hot water service if you just showered on until it ran out? About one hour? OK so that means you can drain it five times faster than re-heat it. So while that hot water tap is on, the energy going down the drain, is the equivalent of – wait for it - 5 x 48 = 240 light globes! I suspect many people, if they could see the 240 globes shining while they were showering, might take much shorter showers.
Whilst of the subject of the energy needed to heat water; think about this. Do you have some of those single lever mixer taps? And are they usually set somewhere in the middle? How many times have you lifted that lever (turning on the equivalent of 240 light globes), long enough to take hot water out of the hot water service, but not long enough to actually get any hot water? Why not just swing it to the cold position? Otherwise you are just paying for something without getting it.
Common myths
Now let’s get onto some common myths and misconceptions. How many of us have heard that fluorescent lights are very efficient? It is certainly true that fluorescent lights are much more efficient than incandescent lights. Here the problem is the sheer numbers of lights installed. A typical 1 to 2-person office may have four twin tube fittings. I’ll let you in on another secret. The tubes may be 36W but the complete fitting (which includes a transformer-like object called the ballast) uses closer to 50W. In a twin tube fitting, that’s about 100 watts so the office comes to four incandescent light globes. I was amused the other day when a friend was leaving his office. He turned off the 50-watt desk lamp (to save energy – well it felt hot) and left on 400W of fluorescent lamps (because they hardly use any energy – well you don’t feel the heat from those, unless you are up close).
Have you heard the myth that it takes more energy to switch lights on and off than leave them on? This is a popular one because it is so convenient to believe. But it isn’t true. Its origin can be traced to a time when fluorescent tubes were new, expensive and their life was shortened by frequent switching. But in terms of energy – an hour switched off is an hour’s worth of energy saved. And it doesn’t use even a little bit more when you switch it on again. Today’s tubes last for tens of thousands of hours whether you switch them or not and they cost about $3. The rationale for leaving them switched on has long passed – if it ever existed. This myth was recently thoroughly debunked on the American “Myth Busters” show on SBS. If you are to leave the room for more than ten minutes, turn the lights off.
Here’s another tidbit of information: In an air-conditioned building, it takes 30W of air conditioner power to extract every 100W of heat generated (by the lights or anything else). So a 100-watt fitting effectively uses about 130W once you take air-conditioning into account.
You might have got the impression from what I have said that fluorescent light tubes are very inefficient. Not at all! They are amongst the most efficient means of lighting – in fact they are more efficient than compact fluorescent lights (CFLs). The problem is the way they are used and over-used. A single unencumbered tube can adequately light a kitchen-sized room or office. Recessed lights with diffusers waste a lot of the light. Newer fittings with reflectors and no diffusers are much better. Finally, you will be surprised when you change older tubes for the new Tri-phosphor types. Their light output is so much higher that you can omit one-third of the tubes and still get the same light level.
12V halogens are huge power wasters
Let’s now look at low voltage down-lights, ie, 12V halogens. Whoever thought that these were a good idea? Not only do they only light a small area, they use lots of power. Because of the 240VAC to 12VAC step-down transformer, each down light, rated at 50W, actually uses about 60W. Many consumers think low voltage means low energy – but nothing could be further from the truth. The main problem with these lights apart from their inherent inefficiency is that too many must be installed to get adequate lighting. It is not uncommon to find six or more in a kitchen – another 400W. There are now compact fluorescent replacements which only use about 11W. Don’t get fooled by the ads, the 9 watt ones are not as bright. I have tried 18-watt incandescent replacements which seem to be quite satisfactory for spot or feature lighting.
Desktop computers are another power hog. How many of us have a desktop computer churning away all day and maybe all night too. These typically use about 120 to 160W although this drops to about half if the monitor switches to standby. Nevertheless, on average it may be about 100W for six hours per day. Think in terms of a Melbourne to Sydney trip each year. The good news is that laptop computers use only about 25W – and even less on standby (my laptop uses a remarkably low half a watt of mains power on standby).
LCD monitors also use less power than CRT monitors - about 20W.
Standby power – the hidden energy gobbler
You may be aware that some appliances use power all the time – even when they are switched off. This “standby power” is largely unnecessary. Until recently, designers of appliances didn’t give this aspect much attention. The result is that many modern appliances can use more energy on standby than doing their job, because they are left permanently on. As an example, consider a typical new washing machine with electronic controls rather than a simple mechanical timer. On standby, when it is doing absolutely nothing, it uses about 5W or 120 watt-hours per day. The machine uses about 50 watt-hours (not counting the energy to heat the water) to do a load of washing. Its direct drive motor is superbly efficient but for the rest of the day it uses 120 watt-hours doing nothing! The solution is to turn it off at the power point.
It is the sheer numbers of these appliances which is the problem. We have microwave ovens, TVs, VCRs, DVD players, sound systems, all with their individual clocks and displays. A typical household might have 10 such units. So unless an appliance actually has time setting functions you need to program – switch it off at the wall. Is there really any need for the TV to sit there all day and night just waiting for you to press the remote control?
(Editor’s note: some home theatre and other entertainment equipment cannot be turned off or you will lose all your preferred settings – another case of bad design).
Here’s another example along those lines. My son recently installed a new split system air-conditioner. It’s a 5-star rated system but here’s the surprise. This air-conditioner draws 10W on standby. Let’s do the calculations: 10W for 24 hours a day, 365 days a year comes to 88kWh per year.
Now let’s work out the likely usage when it is working. Say in Melbourne we have 20 hot days, a year, when it is used for eight hours, and that for those eight hours it runs nearly flat out. That’s a crude assumption but it will serve as an illustration. Running flat out, it draws 550W. Assuming that it’s on for eight hours for 20 days, its air-conditioning energy consumption comes to 88kWh per year! So this 5-star rated appliance uses as much energy on standby, as when it is doing its job. That’s just crazy. What to do? Get it installed with a switch so you can just turn if off completely for most of the time.
Finally, let’s get onto solar. Why don’t we just go solar? This is excellent for water heating. You won’t have to think about 240 light globes, just about wasting water.
Actually, water isn’t just water. There is a substantial energy cost in delivering water to consumers. Think about the infrastructure cost (and energy input) to build and run dams, pipes, pumping stations, water treatment (filtering & chlorination), then sewage pumping and treatment.
But solar for electricity? Well let’s do the sums. A solar panel costs about $10 to provide a watt in brilliant sunshine when the sun is shining straight onto the panel. Panels are sold by this “peak” power. However you have to take into account the varying sun angle, night-time and the weather. For Melbourne or Sydney you find that average power is about one seventh of the peak power. So an average watt costs about $70. Then there are the frames, the installation cost, wiring etc. Generally that doubles the cost again. In some states the Government will pick up a good proportion of the cost. But think of it this way: how much does it cost to save a watt? Changing an incandescent globe to a compact fluorescent saves on average usage (80 watt saving for say 6 hours out of 24) about 20W. Cost to make the change? About $ 7 replaced 10 times over 20 years - say $70. Cost of a solar system to provide an average of 20W? Wait for it: $20 x 70 = $1,400. Or if the government is paying half, about $700. In this example, it costs ten times as much to provide the power as it costs to save it in the first place.
I hope I haven’t depressed you too much but the good news is – the potential for saving energy really is huge – if you just understand where it is all going.
I was sitting with my colleagues having Friday afternoon drinks in our lunch room when I thought about how to present these ideas to them. I counted the double fluoro fittings. Six hundred watts to light a room which has large windows right across one wall. “Look at these lights” I said. “There’s no need for them to be on at all”. “Look those spotlights – lighting the floor behind the desk – when would they ever be useful?” They looked at me askance, as if I had suggested that missing dinner was a good energy saving measure. Were these the same colleagues who asked me if I had seen the Al Gore movie? I hadn’t. But why would anybody who was troubled by the Al Gore message think that even these trivial “sacrifices” were asking too much? I didn’t even get to point out that we had a total of 6000W of lighting switched on. You see the office only has three switches, which are not zoned in any sensible way - so we were lighting the whole office while we were using only one room!
In the next part of this article, we will investigate how to make big savings in water heating and space heating.
How to cut your greenhouse emissions Part 2
More environmental surprises – how a solar water heating can be worse than gas, about fake “green electricity” and how one household reduced their CO2 emissions to a quarter of what they were.
In the last article, I said that solar water heating was an excellent idea. I lied! Well not completely, but I have to tell you a longer story. Seventeen years ago I connected solar water heating panels to our electrically heated off-peak hot water service. It’s still working – that’s the good news. The not-so-good news? Just before the installation we used 5200 kWh per annum for water heating, after installing two panels, 2600 kWh. This is a reduction of 50 %. Why is it so modest? The big problem is that the solar and the electric booster compete with each other. If it is a cloudy day, then overnight, electricity heats the water. If the following day is sunny, the solar has not much to do. The temptation of course is to turn off the electric heater altogether and go 100 % solar. This often works quite well for a while in the summer months. Then the inevitable happens – you run out – and you are the bad guy – the greenie!
Here is a graph of our electricity use for domestic water heating. Obviously 1989 was the year we installed the solar panels. What about the years 1986 – 1996? Why was it always climbing? The answer: Teenagers! We had two boys. By 1997 they had started to behave more responsibly. By about 2003 they had both moved out, as you can see from the graph. In fact you can almost read the history of the family through the hot water service!
The map below shows the proportion of solar contribution you can expect across Australia. As you can see, you need to live in Cairns, Brisbane, Perth or Darwin to get more than 75 % from solar. That last bit boosted by electricity is the unfortunate part.
Let’s consider water heating from the greenhouse gas perspective. One kWh of electricity produced by burning brown coal produces 1.3 kg of carbon dioxide. On average, our solar panels were reducing our CO2 from 5.6 to 3.7 tonnes per year. That’s moderately good. However what if we had just opted for a normal natural gas water heater? The answer to that can be obtained from the Rheem hot water manual. Rheem manufactures both electric and gas heaters and the answer is that we would have used 62 MJ/day, equivalent to 6300 kWh per annum, more than with the pre-solar electric tank, but the carbon dioxide emissions would have been only 1.4 tonnes per annum – less than half of the solar system.
I was not planning to take out my solar system and simply replace it with a gas one. There is a much better way. That is, to use the existing solar as a pre heater for one of the new generation instantaneous type systems. This is no greenie Heath Robinson idea, at least four major manufacturers of hot water systems now offer it. It offers the best of both worlds – a solar system that can do its best without interference from a booster and a gas heater to do the rest. Even better, the instantaneous system does not have heat losses associated with having a flue. I was horrified to discover that a conventional gas storage heater uses 25 MJ/day just keeping the water hot without any being used. To supply 150 litres per day it uses 62 MJ/day. When the unit is sitting there doing nothing while you are away on holidays, three equivalent 100 watt light globes of heat are going up the flue, all day every day. It’s a pretty good reason for turning it off when you go away. The electric storage tank, having no flue, has much lower losses, one 100 watt light globe, on 24 hours a day. That’s equivalent to four Melbourne Sydney trips a year! The gas instantaneous boosted solar system wins handsomely over the others.
To summarize:
Don’t even consider taking out gas to put in solar!
You might ask: why didn’t I do this years ago? Water heating by using electricity is obviously a silly idea – I must have known that. Well I did. But there were several other thoughts. One was that using gas, is using a limited resource whereas there is so much coal that we will never be able to use it all. The climate will stop us. The other thought was that coal fired power stations cannot be rapidly turned off and on. That’s why the power companies sell off-peak electricity very cheaply. The thought that I had, was that the coal burnt overnight will be burnt anyway, whether we use the electricity or not. That’s why they were selling it for a third of the normal price. This was my thinking. So ideally, if you remove yourself from the off-peak load, it would be good to remove yourself from the peak load too. We’ll get on to that shortly.
I have mentioned the advantage of gas to boost solar but I realize that not everyone has this option. A good alternative, although also expensive is the heat-pump water heater. Examples can be checked on http://www.enviro-friendly.com/quantum-heat-pump-water-heater.shtml and http://www.rheem.com.au/domestic_product.asp?model=551310
These devices work by pumping heat from the surroundings into the water, in much the same way as a reverse cycle air-conditioner can pump heat into the house. The advantages are that you don’t need a north facing roof, and you don’t need a gas supply. Heat pumps can provide about 3 times as much heating as a resistive heating element.
So far I have concentrated on water heating, which is because water heating takes about half of the energy used in a household. However now let’s look at a bigger picture, the normal electricity load, for lights, fridge etc. For us, that’s about 2700 kWh/year, which translates into 3.5 tonnes of CO2/year for electricity generated from coal. Before our change to low energy lamps, it was about 4000 kWh/year – 5.2 tonnes. From that down to 3.5 tonnes was a big improvement but what’s the next step? Eliminate the 3.5 tonnes! That could be in done in two ways. We could either spend $18,000 on a grid connected solar photovoltaic system or for $150 per year, buy electricity from a renewable source. For a very obvious reason, we chose the second option.
A word of warning about “green” or “renewable” electricity. You almost certainly have been approached by an electricity company offering “100% renewable” for no extra cost. Don’t believe a word of it! If you have already signed up for this, check your electricity bill. It will tell you how much CO2 has been emitted. My first “100% renewable” bill said “Total greenhouse emissions for this bill: 1.08 tonnes. Total greenhouse savings for this bill 0.15 tonnes”!
How one can describe that as 100% is a mystery and pure deception. In fact of the 40 odd companies/products, there are only three which really provide 100% renewable. The rest, far less. Origin (Solar and Wind) and TRUenergy Windpower do. AGL does, but watch it! Unless you are being quoted about 5 cents extra over the standard rate, you can be sure you are not getting that 100%. The old maxim applies – if it sounds too good to be true – it usually is. And if you do sign up – look at your bill!
Space heating
In Melbourne you need it, at least if you don’t want to be the bad guy who goes around telling everybody to put on sweaters instead of heating the house.
Our house is heated by gas. Space heating, as you can imagine is one of the big energy users and also a big CO2 producer. In the pre-green “business as usual” scenario for us it looked like this:
As you can see, the central heating accounted for about a quarter of the CO2 production of our house. Before we went to gas boosted solar, our gas consumption was due to heating and cooking. Cooking, (we have a gas top only and an electric oven - as many people do) accounted for a very small proportion of our total CO2 production. My wife cooks a lot – for a lot of people. But heating is the big gas user. We were using on average 55,000 MJ (Megajoules) per annum. Gas is sold in MJ whereas electricity in kWh (kilowatt-hours). They are both units of energy. You can convert MJ to kWh by dividing by 3.6. Let’s not dwell on it. To convert MJ to tonnes of CO2 produced, divide MJ by 16,000. Our central heating was producing (55,000/16,000) 3.4 tonnes of CO2 a year. It was an older type with a pilot light. I had already taken the measure of turning off the pilot light during the summer. That was using more gas than the cook-top! I decided, rather than wait until our 13 year old unit actually conked out, to replace it with a 5 star unit with electronic ignition. At the same time we added some insulation to the ceiling, The combined effect (and I can’t tell you how much is due to what) was that we are now using about 39,000 MJ per year, a saving of 1 tonne of CO2 per year.
This graph shows how, between 1992 and 1998, our gas consumption inexorably rose, despite numerous heating service calls. The abrupt drop was when we installed the new heating system. By the way, in 1987 we extended the house so our gas consumption is now about what it was before the extension.
So looking at a more comprehensive picture, on our domestic level, our CO2 reducing journey is now like this:
After taking out the silliness of electric water heating, central heating accounts for the majority of our CO2 production but at least the overall result is quite satisfying. We are producing about a quarter of the CO2 that we out started with.
You will of course be saying “what did all this cost?” Well of course it wasn’t cheap, but it was only a fraction of the price of a four wheel drive, and will last a lot longer! And here’s another way of looking at it. If you drive a large 4WD instead of a normal sized car, it will increase your CO2 production by about 2 tonnes a year from about 4 to 6 tonnes. For a fraction of that cost, you could potentially reduce it by 11 tonnes (from 14 to 3 tonnes/per annum).
What are your priorities?
How to cut your greenhouse gas emissions Part 3
The thinking persons guide.
“If all Australians switched to clean, renewable energy (Green Power) today, Australia's total greenhouse pollution would be cut by 30%.”
Every problem is easy to solve if you know nothing about it. The statement above, is on the WWF – Australia website (http://wwf.org.au/act/takeaction/green-power-200603/),. What was the writer thinking? Did he/she think that just by ringing our electricity suppliers a forest of wind turbines and solar panels would sprout up? Was he/she thinking that they had already been built and someone was just sitting by the phone waiting for us to ring up to throw the switch?
Of course intelligent Silicon Chip readers would not think like this. Renewable energy power sources are damn difficult to build. In Victoria for example a wind farm was held up for a year by the concerned for the orange bellied parrot. (by one assessment, it might kill one parrot every 1000 years). Progress is slow and bedeviled by obstacles technical, political and bureaucratic. But it is typical of the population at large to ignore these problems. Ideas that hydrogen or electric vehicles are the solution to CO2 induced climate change need very careful examination.
Electric cars
I’m not referring hybrid-electric cars, which are a hi-tech way of improving petrol efficiency. This is about purely electric vehicles. There have been some around in the form of delivery vans for years and electric scooters are available. These vehicles are used for specific applications and with good reasons. As far as the general purpose car, as we know it is concerned, you probably realise that the pure electric car- which has the range, convenience and performance of a conventional car – is still way off in the future.
Electric cars are often seen as a way of providing clean, pollution-free transport. However that’s not what you get if the electricity comes from a fossil fuel powered electricity grid. It just moves the pollution from one place to another. The dream is the car which derives its energy from the sun. Is this realistic – and is it a good idea? This question applies equally well to hydrogen, compressed air, flywheel and any other vehicles which store energy derived from electricity in the first place.
Let us look at the energy consumption of a typical car over a year. Let’s make an assumption of a car which does 10,000 km over a year and has fuel consumption of 10 litres per 100 km. Or you could assume a very efficient car using 5 litres/100km over 20,000 km. Whatever assumption you make, won’t affect the outcome. Let’s say, it comes to 1000 litres per year.
One litre of petrol contains about 10 kWh of energy (that’s the energy used by a 100 watt light globe over 100 hours). So a 1000 litres of petrol provides 10 x 1000 = 10,000 kWh of energy to the car’s engine over the year.
Now let’s make another assumption. The efficiency of a car engine is about 25 %. Only one quarter of the energy in the petrol gets to the engine’s output shaft. Again, you can make your own assumption – which won’t affect the outcome. For this case, the engine provides 0.25 x 10 = 2,500 kWh over the year. However an electric motor is not 100 % efficient and nor do you get all the energy stored in a battery back out again. I’m assuming an efficiency of 90%. So we really need about 3000 kWh a year.
Imagine we are to provide these 3,000 kWh each year from solar photovoltaic panels on our roof. How many solar panels would it take and how much would they cost?
The cost of solar panels is about $10 per peak watt. A peak watt is what they output when they are directly facing the sun, with no cloud. Of course in reality we need to take into account night time, cloud and the varying sun angle. Effectively, averaged over a year in south eastern Australia the ratio between peak power and average power is about 7 times. So the real cost of solar panels is about 7 x $10 = $70 per average watt.
To calculate the cost of panels we would need to get our 3,000 kWh in a year, we work out how many watts on average we will need to collect. There are 24 x 365 = 8760 hours in a year. To get the average watts, divide kWh (kilowatt hours) by hours in a year: 3000/8760 = 0.342 kW (kilowatts) or 342 watts.
What would this solar system cost? At $ 70 per average watt, we need about $ 70 x 342 = $24,000 of panels. Generally in solar systems the cost of the panels is about half of the total cost when you include the mounting frames, labour, controllers, wiring etc. So the cost of the installation is likely to be closer to $48,000. However a good solar system will last 20 years or more.
One can image that when petrol is $2.50 a litre and solar cells are cheaper, (at the moment they are not going down in price) that this is not beyond the realms of possibility. But is it a good idea? To answer this, we need to look at various scenarios from the carbon emissions point of view. These are:
1. Drive an ordinary petrol, diesel or LPG powered car. Let’s call it “Petrol”
2. Electric car – charged from the power grid operating predominantly on coal. Let’s call it “Elec/coal”
3. Electric car – charged from a home installed photovoltaic system (grid connected so that surplus can be put into the grid and deficiency is drawn from it. Let’s call it “Elec/PV”
4. Petrol, diesel or LPG car, with same photovoltaic solar system as above – called Petrol/PV
Here is the information we need:
From my electricity bill I can see that 888 kWh resulted in 1.23 tonnes of CO2, that is 1.385 kg/kWh.
From the Australian Greenhouse office – I can find that burning 1 litre of petrol results in 2.6 kg of CO2 being emitted.
So for “Petrol” we multiply the litres per annum by 2.6 to get 2.6 x 1000 = 2,600 kg = 2.6 tonnes of CO2.
For Elec/coal, we have put an extra load of 3000 kWh per annum on the system resulting in 3000 x 1.385 = 4155 kg say 4.2 tonnes of CO2
For Elec/PV, there is no CO2 contribution.
Finally for Petrol/PV, the petrol car will contribute 2.6 tonnes of CO2 whilst the photovoltaic cells pump the same energy back into the grid saving 4.2 tonnes of CO2. The net result is that 4.2 – 2.6 = 1.6 tonnes of CO2 has been saved from entering the atmosphere. Here’s a graph:
You can see that in our present situation, in which most electricity is generated from fossil fuel, electric vehicles combined with coal electricity generation are worse than the status quo. Electric vehicles combined with solar photo-voltaics are good but come with a double cost, that of setting up the solar system as well as the expensive batteries of the car. The winner both CO2 and cost-wise is the conventional car or hybrid-electric car, with independent renewable energy, supplied from solar, wind, geothermal or another renewable source. The good news and interesting thing is that this combination is already available, unlike the grid-charged pure electric car.
Until the last greenhouse gas emitting power station is taken off line, there is no environmental advantage in taking energy out for the grid for powering cars.
Niggling questions
One of the questions a thinking person might ask is “what is the energy or environmental cost of energy saving measures themselves? It is not an easy question to answer. How can one calculate the environmental or energy cost of a compact fluorescent lamp? It has so many components and different materials in it. However, as far as energy is concerned, there is an easy way of thinking about it: If a CFL costs $5, it can only have used $5 worth of energy at an absolute maximum. Otherwise it couldn’t be sold for that price. Of course you could argue that the energy was bought at a lower price. But the lamp was sold at a lower price from the factory than the retail price you paid. So let’s just compare retail with retail. A CFL has the potential to save say 80 watts for 5000 hours which is 400 kWh. That electricity would cost about $50. So it could save up to ten times the maximum possible energy cost of its production. Even considering that it may not last as long as advertised and it might be left on longer than a tungsten lamp, that retail price is the maximum possible energy cost. So energywise it must be worth it.
Another niggling question is the pollution aspect of the production of these lamps. I must say it concerned me too. However, here again there is a relatively simple way of thinking about it. Of course pollution is produced by manufacturing electronic goods and fluorescent tubes. But it is a little known fact that coal fired power stations put a lot of uranium into the atmosphere. And tungsten 5 lamps need mining and energy to produce too. I can’t give you figures on this but you will get the idea. Energy saving devices do have their environmental costs but as a rule-of-thumb, the environmental payback period is similar to the economic payback period. It can be much better, when you are considering highly subsidised energy, such as off peak electricity.
Carbon offset schemes
These are schemes that try to do good, to make up for doing bad. Sounds OK - and planting trees is a great idea. If nothing else, it should at least increase the rainfall and habitat for wildlife – and that’s good. Just to spoil your warm fuzzy feeling, let met tell you that one mature tree extracts about 60 kg of CO2 from the atmosphere a year. If you have an average sort of household with an average energy use, you will be putting about 14 tonnes of CO2 into the atmosphere every year. The car accounts for another 4 tonnes and each overseas trip another 4. Let’s say 20 tonnes a year for the purpose of discussion – an order of magnitude type of calculation. What is 20 tonnes of CO2 in tree equivalents? At 60 kg per tree that works out to 20/0.06 = 333. Please plant them! There is an organisation called Greenfleet that will plant and maintain 17 trees on your behalf for $40 to offset the CO2 for one car. Be aware, that these trees will not be mature for some years. And hope they will cared for and survive. See http://www.greenfleet.com.au/transport/technical.asp
The main problem with a carbon offset scheme is that it can’t go on indefinitely. For decades we have been taking carbon out of the ground (from countless ancient forests) and putting it into the atmosphere. We can’t realistically expect to reverse this by planting trees. We aren’t going to put them back into the ground and we couldn’t if we wanted to. If you check CarbonSMART (http://www.carbonsmart.com.au/pdf/InformationSheet.pdf) you will see that part of the contract for people growing timber on their properties is “The carbon will remain on site for at least 100 years after the final trade of that carbon”.
Another kind of carbon offset scheme is one where you pay for someone else’s energy saving, or reductions of greenhouse gas emissions, where they wouldn’t have the funds to do it themselves. Examples are given in www.myclimate.org. This arrangement supports projects such as solar energy in Eritrea, electricity from Methane in South Africa and wind energy in Madagascar. Look at http://www.myclimate.org/index.php?lang=en&m=projects These project have a double benefit. – to that community and to the environment in general.
“Carbon offsetting” and “carbon neutrality” has suddenly sprung up as a growth industry (no pun intended). However as with any new industry, it is full of cowboys. There are now organizations which try to evaluate this, for example Total Environment Centre www.tec.org.au
Where to from here?
We have talked about how to reduce our energy use and how to offset the CO2 we do produce. However if we are ever going to make serious inroads into the looming climate change problem, we will have to do more. What we need is serious affordable alternatives to old fashioned coal.
What are our best options for renewable energy? The main alternatives as we know them today are shown in the graph below. In the cases where there are greenhouse gas emissions, the cost of CO2 has been added at $60/tonne, to give a total effective cost.
A graph such as this is of course highly controversial and various camps will claim much higher or lower costs depending on their particular bent.
It is interesting to note that in the media, Nuclear, Solar Wind and Geo-sequestration are frequently mentioned. How often is Geothermal mentioned in the press? Hardly ever. Why is this so? Maybe it is that both the coal and the uranium industries have powerful political lobbies associated with them. Geothermal obviously doesn’t carry any political clout.
Hot Fractured Rock Geothermal
Unknown to much of the population, Australia has huge reserves of hot rock geothermal energy. This differs from “conventional” geothermal energy which is associated with volcanic activity and used in New Zealand. In Hot Fractured Rock, (HFR) water is pumped down an injection well into heat-producing granites located 3 kilometres or more below the surface. Temperatures of up to 300 degrees are obtained and the water is circulated through a heat exchanger. Australia’s recoverable HFR resources are capable of satisfying current electricity consumption for over 450 years. The Cooper Basin in South Australia alone could provide emission-free base-load electricity for 70 years. Although it is technologically difficult, it is composed of solvable problems, mostly using existing oil drilling technology. When compared with nuclear with its multiple thorny issues of safe disposal, security against terrorism and accidents, it seems a very attractive proposition. The major advantage Geothermal has over wind and solar is that it suitable for base-load supply. It can be regulated to match the load, rather than being at the whim of the elements.
A major advantage of the Cooper Basin is that it is a long way from any population centres. The Swiss city of Basel has a HDR (Hot Dry Rock) geothermal power station pilot project which has just recently been put on hold, after three earth tremors over three on the Richter scale were experienced. Since then an argument has developed as to whether the drilling allowed minor slippage to occur (a practice used on the San Andreas Fault), thus averting a bigger earthquake, or if it is the cause of quakes which would otherwise never happen.
Thorium fuelled nuclear power
Thorium is a fuel that can be used in nuclear reactors but produces very little nuclear waste and what there is, has a half-life of hundreds, rather than millions of years. Thorium reactors are what is called sub-critical, so no runaway reaction can occur. Furthermore, Thorium is 10 times as abundant as uranium and Australia has huge reserves of it. Sounds too good to be true? Maybe, and certainly if you search on the web you can find plenty of criticism and opposition to the idea. Having said that, Norway, which currently bans the use of nuclear power, is now investigating it. Obviously the jury is out, but who knows – it might be that a more benign form of nuclear power will emerge.
Our journey
In the beginning I talked about how much energy various domestic appliances activities use and how we could reduce it. Some surprises included:
While taking a shower you are using the energy equivalent of 240 light bulbs.
Leaving a light on every night for a year used as much energy as driving from Melbourne to Sydney.
Electrically boosted solar water heating is worse than gas.
Fluorescent lights are not necessarily low energy!
Leaving them on never saves energy.
Low voltage halogen downlights are the worst.
We learned that various “low energy” appliances use more energy sitting there doing nothing than doing their job.
After having given you the bad news, on how much energy everything uses, we saw how, by making the right choices and spending a bit of money, one could do a lot better. But we also learned about the dishonest practices of the electricity suppliers and how to get wise to their tricks.
On the second leg of the journey, I introduced a real liability, space heating and how even there, there were improvements to be made. By using a combination of all tactics, our household managed to get its CO2 emissions down to one quarter of the “business as usual” scenario.
On this last leg we have moved on to deal with energy usage over which we have less control by using methods such as carbon offsets. Even then, there are choices to be made and some of them make more sense than others.
Finally we moved into the arena of government policy and discovered (surprise!) that the government actions and the technologies they support don’t make a lot of sense.
I hope I have alerted you to some of the foibles we are led to believe. As informed citizens we can do a better job.
To Silicon Chip Mailbox
Electric cars and how to charge them
Some readers might jump to the conclusion that SC and some contributors are anti energy conservation. After all, we appear to have been critical of CFLs, solar hot water, carbon offsets, electric cars, solar photovoltaics. "green" electricity etc. But far from being anti conservation, I’m just anti hype. I feel we should try to dispel the myth that just by clicking a few boxes and making a few phone calls or spending some money on some “green” product, you can be "off the hook" and carry on as usual, "carbon neutral". This I see as a hazard. An industry has sprung up to assuage peoples' consciences without necessarily doing much to improve the situation.
Since a number of readers have commented on my somewhat pessimistic analysis re electric cars and their effectiveness in reducing greenhouse gas emissions, I would like to refer to an excellent paper by Erberhard and Tarpenning of Tesla Motors, a manufacturer of electric cars.
http://www.teslamotors.com/display_data/twentyfirstcenturycar.pdf
This paper goes a lot further than my simplistic analysis. It compares a state-of-the-art electric car with state-of-the-art electricity generation from natural gas. The result is that the electric car is twice as efficient as a Prius hybrid car. I have no problems with this conclusion except that it’s comparing a sports car with a family car.
The article bases its calculations on electricity generated from a combined cycle natural gas generator plant, which is as efficient as they get. This kind of power station uses a gas turbine and the waste heat generates steam to drive a second turbine. The plant efficiency is 60% but the paper goes further to calculate the gas-well-to-electric-outlet efficiency as 52.5%
As far as the Australian scene is concerned; we have a coal-mine-to-electric-outlet-efficiency in the 25% region. 78 % of Australian electricity is generated from coal. That means that effectively a pure electric car using electricity generated by coal is similar to the Prius. Here are the calculations:
Let's consider 3000 kWh/year of electricity. This was the number used in my previous article so I will stick with it.
1. If we put solar array up, it will we save 1.385 * 3000 = 4.2 tonnes/annum of CO2 in dirty old Victoria and about 0.9 * 3000 = 2.7 tonnes in WA for example.
2. From the 21st Century Car article, (page 2) I get the figure of 2.18 km/MJ electrical-outlet-wheel efficiency. Converting to kWh gives 2.18 * 3.6 = 7.85km/kwh
3. From the above, you can figure out that the distance you can go on 3000 kWh with that electric car is 7.85 * 3000 = 23,544 km (impressive).
4. The Prius is quoted at anything between 3.9 and 5.9 l/100km but I'll assume an average of the 8 numbers I found, ie 4.7 litres/100 km.
5. at that consumption, to cover the same km as the electric car the Prius would use: 4.7 * 23544/100 = 1100 litres.
6. In the previous articles I used a CO2 loading of 2.6 kg/litre but that ignored the drilling, transporting, refining etc of the petrol which has an efficiency of 81.7 %, making the effective loading 2.6/0.817 = 3.18. (this factor is often ignored).
7. Now we can plot a graph which shows how much CO2 is produced by charging the vehicle with electricity from generators with any given kg CO2/ kWh.
Electric Car vs Prius analysis
Assumptions:
No manufacturing or recycling costs included
Oil transportation and refining included
Benchmarks for kg CO2/kWh
Victoria 1.4
NSW and Australian average 1.0
WA 0.9
Natural gas single cycle 0.6
Combined cycle gas/steam 0.33
Note: Both vehicles travel 23,544 km per annum, an unrealistic distance but the relationship between the graphs is the same. For a more realistic distance, divide the y axis by 2.
We can now use this graph to draw our conclusions:
1. Below 1.17 kg CO2/kWh electricity generation, this (2 seater) electric car is less CO2 polluting than a Prius.
2. We need a more practical electric car.
3. We need to be heaps better at generating electricity!
Whether you have a solar PV array on your roof is irrelevant. It could be on the house next door and that wouldn’t change the conclusions. It is only when a lot of people have solar panels and/or a lot of renewable power stations are built, that the average kg CO2/kWh of the grid will come down.
I can only agree with all the other usually quoted benefits of electric cars. I can only agree on the need and potential to improve the performance of electricity generation.
I will still point out that we are comparing a 2 seater Roadster with the Prius, a 5 seater family car.
Ideally the comparison should include the total Dust to Dust analysis as is done by CNW research - see http://www.cnwmr.com/nss-folder/automotiveenergy/
It's an excellent site. This organization looks at every aspect of the car’s life from mining and refining the materials to build it, running it, servicing it, repairing it etc. It takes into account the recycling, the time the car will last and even the efficiency of the offices of the car’s manufacturer. It takes into account transportation of materials and the product. The manual for understanding it all, goes to about 450 pages. CNW published these results in an Excel spreadsheet. It used to be free now costs quite lot. However I have some data from when it was still free, a year ago. The bottom line is expressed in $/mile. I think this includes the carbon cost. needs checking
The fascinating thing about this analysis is that vehicles like the Prius and the Honda Civic hybrid come out at about $3.2/mile whereas the Corolla comes out at $0.73/mile. Why is this so? Because hybrids cars are very complicated pieces of equipment with lots of exotic materials which are hard to recycle. On the other hand the Corolla is made as simply as possible and in large quantities. The point here is that fuel consumption isn’t everything. Now how all that pans out with an electric vehicle, I have to confess, I have no idea. CNW only examines commercially available vehicles. I expect that in time they will do pure electric vehicles too. It could be that the extreme simplicity of the pure electric vehicle will be its biggest advantage. Hopefully the issues of battery manufacturing and recycling are not too onerous.
Another very important point on fuels for transport is the dependence on foreign oil. We all agree that it’s unhealthy. For Australia the answer I feel is a combination of electric vehicles, for small commuter type use and natural gas in the form of LPG for larger ones. Although larger cars are being converted, apparently there are efficiency compromises. Cars built to run on LPG produce very good results. This is well covered in a document “Life Cycle Emissions Analysis of Fuels for Light Vehicles” by the Australia Greenhouse Office, 2004 conducted by the CSIRO.
Another option for “renewable” fuels is to grow them. I have friends who run their diesel 4WDs on fish and chip oil – and it works very well. Of course that is never going to be a solution for a whole population, only a small bunch of enthusiasts. So what about growing fuel?
Biofuels, in some countries are starting to look like a seriously bad idea. The UK and European demand for biofuels has resulted in brutal landgrabbing from peasants in South America to grow African Oil Palm. In some areas there have been hundreds of assassinations and disappearances. Rainforest is being cleared. When that happens a successful oil plantation will take as much as 50 years before it had regained the carbon sent up in smoke.
When compared to biofuels, electric cars are a clear winner.
My take on this is: we need to do a lot of work to improve our electricity generation. We have neglected power station efficiency for decades. We need to do an awful lot of catching up. But the last thing we need now is an extra load on the system to increase the number of stations we need to build. Did you know that Australian fossil fuel electricity generation is still increasing in spite of the uptake of renewables?
Perhaps I'm being bit too negative about this. It makes me think of those pronouncements along the lines of "I think there is a world market for maybe five computers”. (Thomas Watson of IBM, 1943), or "Heavier-than-air flying machines are impossible." (Lord Kelvin, president, Royal Society, 1895). However I do not think that electric cars are not viable. I think we should look at what direction we should be investing our efforts.
Re the running costs of electric cars, look at it this way: Say we compare a car run directly from LPG vs an electric car charged from electricity supplied by gas. LPG costs about 50 cents per litre or say 5 cents per km, similar to the costs of electric vehicles of comparable size which is an important point. Calculations from the 21st Century Car report come to 2.2 cents per km for a 2 seater car.
Finally on this pricing topic, I want to point out that whether you use LPG or electricity for vehicles, you are not paying anything for road maintenance, in contrast to those who use petrol and diesel.
I actually would love to have or build/covert an electric car but my logic tells me that in Victoria it doesn't make sense.
To return to the subject of electricity generation.
A reader recently wrote that he bought a 2.1 kW array of solar panels. It cost $25,000 complete including inverter and installation, the federal government gave him a rebate of $8000. Buying the solar panels gave him carbon credits worth a further $1000.
I am delighted to hear that the price of installed PV power has come down so much. Let’s look at these figures. For Melbourne or Sydney the factor between peak and average power is about 7. So a 2.1 kW array has a mean output of 300 watts. The inverter has an efficiency of about 90% and realistically, solar installations are de-rated at 90% because output drops with temperature. So that makes the effective output 243 watts or 2129 kWh/year. At current Melbourne prices of 13 cents per kWh that’s $278 worth of electricity per year. Cost of installation after the rebate and credits is $16,000. To get that back, as a very crude guesstimate: 16000/278 = 59 years. Now I freely admit that electricity will probably go up faster than inflation and indeed it should. The real point here is that electricity in Australia is ridiculously cheap – making renewable energy and conservation almost always not worth it. To put it another way, $16,000 invested at 6% returns about $960/ year, which means the electricity costs 960/2129 = $ 0.45 /kWh or 45 cents/kWh. Without the government rebates this would be 70 cents/kWh. And that calculation didn’t include the replacement cost of the installation at the end of its life.
But there are more efficient ways, albeit nor for us as individuals: Victoria has just commenced a new Solar power station, see http://www.solarsystems.com.au/projects.html. This is a 154 MW Heliostat plant which will cost $420 million. The cost per kWh based on the same sort of calculation, gives a price of 7.9 cents/kWh. Wouldn’t it be more sensible for us as a nation to put money into installations such as this rather than subsidising individual domestic systems where the cost effectiveness is only an eighth of a large station? We need to spend our dollars effectively. When it comes to that of course, Wind power is a good contender, cheaper than solar by a factor three. However it is difficult to find suitable sites that are acceptable to the public. One of the downsides of wind is that it divides conservationists into vigorous pro and anti groups. And it doesn't, like solar, provide baseload. That's why I see Geothermal as worth pursuing.
As much as I would love to put a domestic, grid connected solar system on my house, again my logic says it doesn’t make sense. However; what if I were to move my solar array to a much sunnier place, say the Kimberley? And if the electricity at that place cost 3 times as much as it does in Melbourne? Wouldn’t that make it a good proposition? True – people won’t be able to see the array on my house to show off how green I am. I am supporting the building of a 32 kW (peak) solar installation in the Kimberley. It is on the Australian Wildlife Conservancy property "Mornington Wildlife Sanctuary". The approach is to try to spend my money on things that maximize the benefit. The WA government will provide 55% of the capital cost. In the reader’s example above, the rebate was effectively only 33%. The added bonuses are that AWC reduce their diesel bill whilst I get a tax deduction. Of course if you cannot afford $16,000 any amount of money would help with the solar at Mornington.
As to the fundamental cost of photovoltaic arrays, it seems that every month another breakthrough is announced. We had the Suncube, Sliver technology and as a recent example, www.avasolar.com.
AVA is promising solar panels at $1 per watt with production starting at the end of next year. “Cost to the consumer could be as low as $2 per watt, about half the current cost of solar panels”. We have been waiting a long time for these breakthroughs to reach the market. But it can happen. I remember when I bought my first compact fluorescents, they were $42 ! But I believed that by buying them and supporting the fledgling industry it would become commercially attractive. And so it did. CFLs now cost as little as $2.50. The same has not yet happened to solar PVs.
What can be done to accelerate the development of green technologies? In this I would include electric cars, geothermal electricity generation, safe nuclear power based on Thorium, and of course more economical solar PVs. Well it might come as a surprise to you to hear that energy and transport subsidies in Australia are $10 billion per annum. That’s $500 per capita. Of that $10 billion, less than 4% of subsidies provide support for renewable energy and energy efficiency. The rest is for fossil fuels (see Institute for Sustainable Futures, UTS Energy and transport subsidies in Australia by Chris Riedy). Just imagine what could be achieved if this situation were reversed. Any politicians out there reading this?