Noise in Computer Rooms

Some people think that you can recognise a good restaurant by the presence of obscure dishes on the menu or having high prices. The reality is that there are two ways of quickly identifying a good restaurant, one is the Michelin Guide [1] (or a comparable guide – if such a thing exists), the other is how quiet the restaurant is.

By a quiet restaurant I certainly don’t mean a restaurant with no customers (which may become very noisy once customers arrive). I mean a restaurant which when full will still be reasonably quiet. Making a restaurant quiet is not in itself a sufficient criteria to be a good restaurant – but it’s something that is usually done after the other criteria (such as hiring good staff and preparing a good menu) are met.

The first thing to do to make a room quiet is to have good carpet. Floor boards are easy to clean and the ratio of investment to lifetime is very good (particularly for hard wood), but they reflect sound and the movement of chairs and feet makes noise. A thick carpet with a good underlay is necessary to absorb sound. Booths are also good for containing sound if the walls extend above head height. Decorations on the walls such as curtains and thick wallpaper also absorb sound. A quiet environment allows people to talk at a normal volume which improves the dining experience.

It seems to me that the same benefits apply to server rooms and offices, with the benefit being more efficient work. I found it exciting when I first had my desk in a server room (surrounded by tens of millions of pounds worth of computer gear). But as I got older I found it less interesting to work in that type of environment just as I found it less interesting to have dinner in a noisy bar – and for the same reasons.

For a server room there is no escaping the fact that it will be noisy. But if the noise can be minimised then it will allow better communication between the people who are there and less distraction which should result in higher quality of work – which matters if you want good uptime! One thing I have observed is that physically larger servers tend to make less noise per volume and per compute power. For example a 2RU server with four CPUs seems to always make less noise than two 1RU servers that each have two CPUs. I believe that this is because a fan with a larger diameter can operate at a lower rotational speed which results in less bearing noise and the larger fans also give less turbulence. While it’s obvious that using fewer servers via virtualisation has the potential to avoid noise (both directly through fans and disks and indirectly through the cooling system for the server room [2]). A less obvious way of reducing noise is to swap two 1RU servers for one 2RU server – although my experience is that for machines in a similar price band, a 2RU server often has comparable compute power (in terms of RAM and disk capacity) to three or four 1RU servers.

To reduce noise both directly and indirectly it is a requirement to increase disk IO capacity (in terms of the number of random IOs per second) without increasing the number of spindles (disks). I just read an interesting Sun blog covering some concepts related to using Solid State Disks (SSDs) on ZFS for best performance [3]. It seems that using such techniques is one way of significantly increasing the IO capacity per server (and thus allowing more virtual servers on one physical machine) – it’s a pity that we currently don’t have access to ZFS or a similar filesystem for Linux servers (ZFS has license issues and the GPL alternatives are all in a beta state AFAIK). Another possibility that seems to have some potential is the use of NetApp Filers [4] for the main storage of virtual machines. A NetApp Filer gives a better ratio of IO requests per second to the number of spindles used than most storage array products due to the way they use NVRAM caching and their advanced filesystem features (which also incidentally gives some good options for backups and for detecting and correcting errors). So a set of 2RU servers that have the maximum amount of RAM installed and which use a NetApp Filer (or two if you want redundancy) for the storage with the greatest performance requirements should give the greatest density of virtual machines.

Blade servers also have potential to reduce noise in the server room. The most significant way that they do this is by reducing the number of power supplies, instead of having one PSU per server (or two if you want redundancy) you might have three or five PSUs for a blade enclosure that has 8 or more blades. HP blade enclosures support shutting down some PSUs when the blades are idling and don’t need much power (I don’t know whether blade enclosures from other vendors do this – I expect that some do).

A bigger problem however is the noise in offices where people work. It seems that the major responsible for this is the cheap cubicles that are used in most offices (and almost all computer companies). More expensive cubicles that are at almost head-height (for someone who is standing) and which have a cloth surface absorb sound better significantly improve the office environment, and separate offices are better still. One thing I would like to see is more use of shared desktop computers, it’s not difficult to set up a desktop machine with multiple video cards, so with appropriate software support (which is really difficult) you could have one desktop machine for two, or even four users which would save electricity and reduce noise.

Better quality carpet on the floors would also be a good thing. While office carpet wears out fast adding some underlay would not increase the long-term cost (it can remain as the top layer gets replaced).

Better windows in offices are necessary to provide a quiet working environment. The use of double-glazed windows with reflective plastic film significantly decreases the amount of heating and cooling that is required in the office. This would permit a lower speed of air flow for heating and cooling which means less noise. Also an office in a central city area will have a noise problem outside the building, again double (or even triple) glazed windows help a lot.

Some people seem to believe that an operations room should have no obstacles (one ops room where I once worked had all desks facing a set of large screens that displayed network statistics and the desks were like school desks with no dividers), I think that even for an ops room there should be some effort made to reduce the ambient noise. If the room is generally reasonably quiet then it should be easy to shout the news of an outage so that everyone can hear it.

Let’s assume for the sake of discussion that a quieter working environment can increase productivity by 5% (I think this is a conservative assumption). For an office full of skilled people who are doing computer work the average salary may be about $70,000, and it’s widely regarded that to factor in the management costs etc you should double the salary – so the average cost of an employee would be about $140,000. If there are 50 people in the office then the work of those employees has a cost of $7,000,000 per annum. A 5% increase in that would be worth $350,000 per annum – you could buy a lot of windows for that!

Pollution and Servers

There is a lot of interest in making organisations “green” nowadays. One issue is how to make the IT industry green. People are talking about buying “offsets” for CO2 production, but the concern is that some of the offset schemes are fraudulent. Of course the best thing to do is to minimise the use of dirty power as much as possible.

Of course the first thing to do is to pay for “green power” (if available) and if possible install solar PV systems on building roofs. While the roof space of a modern server room would only supply a small amount of the electricity needed (maybe less than needed to power the cooling) every little bit helps. The roof space of an office building can supply a significant portion of the electricity needs, two years ago Google started work on instralling Solar PV panels on the roof of the “Googleplex” [1] with the aim of supplying 30% of the building’s power needs.

For desktop machines a significant amount of power can be saved if they are turned off overnight. For typical office work the desktop machines should be idle most of the time, so if the machine is turned off outside business hours then it will use something close to 45/168 of the power that it might otherwise use. Of course this requires that the OS support hibernation (which isn’t supported well enough in Linux for me to want to use it) or that applications can be easily stopped and restarted so that the system can be booted every morning. One particular corner case is that instant-messaging systems need to be server based with an architecture that supports storing messages on the server (as Jabber does [2]) rather than requiring that users stay connected (as IRC does). Of course there are a variety of programs to proxy the IRC protocol and using screen on a server to maintain a persistent IRC presence is popular among technical users (for a while I used that at a client site so that I could hibernate the PowerMac I had on my desktop when I left the office).

It seems that most recent machines have BIOS support for booting at a pre-set time. This would allow the sys-admin to configure the desktop machines to boot at 8:00AM on every day that the office is open. That way most employees will arrive at work to find that their computer is already booted up and waiting for them. We have to keep in mind the fact that when comparing the minimum pay (about $13 per hour in Australia) with the typical electricity costs ($0.14 per KWh – which means that a desktop computer might use $0.14 of electricity per day) there is no chance of saving money if employee time is wasted. While companies are prepared to lose some money in the process of going green, they want to minimise that loss as much as possible.

The project dedicated to saving energy on Linux systems reports that Gigabit Ethernet uses about 2W more power than 100baseT on the same adapter [3]. It seems most likely that similar savings can be achieved from other operating systems and also from other network hardware. So I expect that using 100baseT speed would not only save about 2W at the desktop end, but it would also save about 2W at the switch in the server-room and maybe 1W in cooling as well. If you have a 1RU switch with 24 Gig-E ports then that could save 48W if the entire switch ran at 100baseT speed, compared to a modern 1RU server which might take a minimum of 200W that isn’t very significant.

The choice of server is going to be quite critical to power use, it seems that all vendors are producing machines that consume less power (if only so that they can get more servers installed without adding more air-conditioning), so some effort in assessing power use before purchase could produce some good savings. When it comes time to decommission old servers it is a good idea to measure the power use and decommission the most power hungry ones first whenever convenient. I am not running any P4 systems 24*7 but have a bunch of P3 systems running as servers, this saves me about 40W per machine.

It’s usually the case that the idle power is a significant portion of the maximum power use. In the small amount of testing I’ve done I’ve never been able to find a case where idle power was less than 50% of the maximum power – of course if I spun-down a large number of disks when idling this might not be the case. So if you can use one virtual server that’s mostly busy instead of a number of mostly idle servers then you can save significant amounts of power. Before I started using Xen I had quite a number of test and development machines and often left some running idle for weeks (if I was interrupted in the middle of a debugging session it might take some time to get back to it). Now if one of my Xen DomU’s doesn’t get used for a few weeks it uses little electricity that wouldn’t otherwise be used. It is also possible to suspend Xen DomU’s to disk when they are not being used, but I haven’t tried going that far.

Xen has a reputation for preventing the use of power saving features in hardware. For a workstation this may be a problem, but for a server that is actually getting used most of the time it should not be an issue. KVM development is apparently making good progress, and KVM does not suffer from any such problems. Of course the down-side to KVM is that it requires an AMD64 (or Intel clone) system with hardware virtualisation, and such systems often aren’t the most energy efficient. A P3 system running Xen will use significantly less power than a Pentium-D running KVM – server consolidation on a P3 server really saves power!

I am unsure of the energy benefits of thin-client computing. I suspect that thin clients can save some energy as the clients take ~30W instead of ~100W so even if a server for a dozen users takes 400W there will still be a net benefit. One of my clients does a lot of thin-client work so I’ll have to measure the electricity use of their systems.

Disks take a significant amount of power. For a desktop system they can be hibernated at times (an office machine can be configured such that the disks can spin-down during a lunch break). This can save 7W per disk (the exact amount depends on the type of disk and the efficiency of the PSU – (see the Compaq SFF P3 results and the HP/Compaq Celeron 2.4GHz on my computer power use page [4]). Network booting of diskless workstations could save 7W for the disk (and also reduce the noise which makes the users happy) but would drive the need for Gigabit Ethernet which then wastes 4W per machine (2W at each end of the Ethernet cable).

Recently I’ve been reading about the NetApp devices [5]. By all accounts the advanced features of the NetApp devices (which includes their algorithms for the use of NVRAM as write-back cache and the filesystem journaling which allows most writes to be full stripes of the RAID) allow them to deliver performance that is significantly greater than a basic RAID array with a typical filesystem. It seems to me that there is the possibility of using a small number of disks in a NetApp device to replace a larger number of disks that are directly connected to hosts. Therefore use of NetApp devices could save electricity.

Tele-commuting has the potential to save significant amounts of energy in employee travel. A good instant-messaging system such as Jabber could assist tele-commuters (it seems that a Jabber server is required for saving energy in a modern corporate environment).

Have I missed any ways that sys-admins can be involved in saving energy use in a corporation?

Update: Albert pointed out that SSD (Solid State Disks) can save some power. They also reduce the noise of the machine both by removing one moving part and by reducing heat (and therefore operation of the cooling fan). They are smaller than hard disks, but are large enough for an OS to boot from (some companies deliberately only use a small portion of the hard drives in desktop machines to save space on backup tapes). It’s strange that I forgot to mention this as I’m about to buy a laptop with SSD.

LUV Meeting July 2008

At the last two meetings of LUV [1] I’ve given away old hardware. This month I gave away a bunch of old PCI and AGP video cards, a heap of PC power cables, and some magnets (which I received for free because they were in defective toys that could seriously injure or kill children). One new member was particularly happy that at the first meeting he attended he received some free hardware (I hope it works – most of that stuff hasn’t been tested for over a year and I expect that some would fail). Also there was another guy giving away hardware, so I might have started a trend of giving away unused hardware at meetings (he was giving away some new stuff in the original boxes, mostly USB and firewire cables).

For a long time (many years) at LUV meetings there have been free text books given away. One member reviews books and then gives them away after he has read them.

At the meeting Ralph Becket gave a presentation on the Mercury functional language. It was interesting to note that Mercury can give performance that is close to C (within 80%) on LZW compression (which is apparently used as a benchmark for comparing languages). Given the number of reasonably popular languages which don’t give nearly that level of performance I think that this is quite a good result.

After the meeting Richard Keech demonstrated his electric car. It’s a Hyundai Getz which has had the engine replaced by an electric motor but which still uses the manual gearbox. Richard did a bit of driving around with various LUV members as passengers to demonstrate what the car can do. Unfortunately I didn’t get a chance to be involved in that, so I’ll have to do so next time I meet him. One thing to note is that Richard’s car was not built that way by Hyundai, it was a custom conversion job. The down-side to this of course is that it would have cost significantly more than a vehicle with the same technology that was manufactured. One design trade-off is that Richard had batteries installed in the place for a spare tire. Last year the RACV magazine published a letter I wrote suggesting that small cars should be designed without a spare tire and that owners of such cars should rely on the RACV to support them if they get a flat tire [2], my option has not changed in the last year, I still think that cars which are driven in urban areas don’t really need spare tires so I don’t think that Richard is losing anything in this regard.

The motor driving Richard’s car runs on three-phase AC and a solid-state inverter is used to convert 185V DC to about the same voltage at three phase AC (I didn’t write notes so I’m running from memory). Apparently on long drives the inverter gets cooler rather than hotter – I had expected that there would be enough inefficiency in the process of converting DC to AC that it would get hot.

In a previous conversation Richard told me that he can drive his car 75Km on one charge and that it takes him 8 hours to charge when using an Australian mains (240V) plug rated at 10A. When designing such a vehicle it would be trivial to make it use a 20A plug for a 4 hour charge or even a two-phase plug for even shorter charging (I’m sure that Richard could have requested these options if he wanted them). But an 8 hour charge allows the vehicle to be completely charged during a working day and the use of the most common type of plug (the type used in every home and office) means that it can be charged almost anywhere (the standard mains circuit used in Australia is rated at 15A so special wiring is needed for a 20A socket). There is such a power point mounted on the outside of my house not too far from where a visitor could park their car. I anticipate that in a few years time it will not be uncommon for people who visit me to charge their car during their visit. Richard’s ratio of an hour of charge to almost 10Km of driving means that someone who visits for dinner could get enough charge into their car to allow for 30Km of driving before they leave. 30Km is about the driving distance to go from my house to a location on the other side of the city that is just outside the main urban area, so probably at least half of Melbourne’s population lives within a 30Km driving distance from my house. Not that I expect friends to arrive at my house with their car battery almost flat, but it does make it easier to plan a journey if you know that at point A you will be able to get enough charge to get you to point B.

I think it’s a good thing to have members of LUGs give things away to other people and to demonstrate technology that is of wide interest. I hope to see more of it.

Car vs Public Transport to Save Money

I’ve just been considering when it’s best to drive and when it’s best to take public transport to save money. My old car (1999 VW Passat) uses 12.8L/100km which at $1.65 per liter means 21.1 cents per km on fuel. A new set of tires costs $900 and assuming that they last 20,000km will cost 4.5 cents per km. A routine service every 10,000Km will cost about $300 so that’s another 3 cents per km. While it’s difficult to estimate the cost per kilometer of replacing parts that wear out, it seems reasonable to assume that over 100,000Km of driving at least $20,000 will be spent on parts and the labor required to install them, this adds another 20 cents per km.

The total then would be 48.6 cents per km. The tax deduction for my car is 70 cents per km of business use, so if my estimates are correct then the tax deductions exceed the marginal costs of running a vehicle (the costs of registration, insurance, and asset depreciation however make the car significantly more expensive than that – see my previous post about the costs of owning a small car for more details [1]). So for business use the marginal cost after tax deductions are counted is probably about 14 cents per km.

Now a 2 hour ride on Melbourne’s public transport costs $2.76 (if you buy a 10 trip ticket). For business use that’s probably the equivalent cost to 20Km of driving. The route I take when driving to the city center is about 8Km, that gets me to the nearest edge of the CBD (Central Business District) and doesn’t count the amount of driving needed to find a place to park. This means the absolute minimum distance I would drive when going to the CBD would be 16Km. The distance I would drive on a return trip to the furthest part of the CBD would be almost exactly 20km. So on a short visit to the central city area I might save money by using my car if it’s a business trip and I tax-deduct the distance driven. A daily ticket for the public transport is equivalent to two 2 hour tickets (if you have a 10 trip ticket then if you use it outside the two hour period it becomes a daily ticket and uses a second credit). If I could park my car for an out of pocket expense of less than $2.76 (while I can tax-deduct private parking it’s so horribly expensive that it would cost at least $5 after deductions are counted) then I could possibly save money by driving. There were some 4 hour public parking spots that cost $2.

So it seems that for a basic trip to the CBD it’s more expensive to use a car than to take a tram when car expenses are tax deductible. For personal use a 5.7km journey would cost as much as a 2 hour ticket for public transport and a 11.4km journey would cost as much as a daily ticket. The fact that public transport is the economical way to travel for such short distances is quite surprising. In the past I had thought of using a tram ticket as an immediate cost while considering a short car drive as costing almost nothing (probably because the expense comes days later for petrol and years later for servicing the car).

Also while there is a lot of media attention recently about petrol prices, it seems that for me at least petrol is still less than half the marginal cost of running a car. Cars are being advertised on the basis of how little fuel they use to save money, but cars that require less service might actually save more money. There are many cars that use less fuel than a VW Passat, and also many cars that are less expensive to repair. It seems that perhaps the imported turbo-Diesel cars which are becoming popular due to their fuel use may actually be more expensive than locally manufactured small cars which have cheap parts.

Update: Changed “Km” to “km” as suggested by Lars Wirzenius.

Record Oil Prices

MarketWatch reports that oil prices had the biggest daily gain on record, going up $11 in one day.

They claim that this is due to an impending Israeli attack on Iran and a weak US economy. $150 per barrel is the price that they predict for the 4th of July. That’s an interesting choice of date, I wonder whether they will be talking about “independence from Arabian oil”…

The New York Times has an interesting article on fuel prices [1]. Apparently sales of SUVs are dropping significantly.

The US senate is now debating a cap on carbon-dioxide production. The NY Times article suggests that if the new “carbon taxes” could be combined with tax cuts in other areas. If implemented correctly it would allow people who want to save money to reduce their overall tax payments by reducing fuel use. Also as increasing prices will decrease demand (thus decreasing the price at import time) it would to some degree mean transferring some revenue from the governments of the middle east to the US government.

The article also states that the Ford F series of “pickup trucks” was the most popular line of vehicles in the US for more than 20 years! But last month they were beaten by the Toyota Corolla and Camry and the Honda Civic and Accord. Now Ford needs to put more effort into their medium to large cars. With the hybrid Camry apparently already on sale in the US (their web site refuses to provide any information to me because I don’t have Flash installed so I can’t check) and rumored to be released soon in other countries Ford needs to put some significant amounts of effort into developing fuel efficient vehicles.

According to a story in the Herald Sun (published on the 23rd of April), survey results show that 1/3 of Victorians would cease using their car to get to work if the petrol price reached $1.75/L [2]. Now the Herald Sun has run a prediction (by the assistant treasurer and the NRMA) that $1.75/L will be reached next week (an increase of just over 10 cents a liter) [3].

The good news is that there will be less pollution in Australia in the near future (even if $1.75 is not reached I am certain that the price will increase enough to encourage some people to use public transport). The bad news is that our public transport is inadequate at the moment and there will be significant levels of overcrowding.

Solar Powered PC

I’ve just read an interesting post on about a solar powered PC [1]. It describes all the steps involved in creating a modern high-performance low-power computer.

They have a lot of interesting information. One surprising fact (from page 3) is that the PSUs tested (both for AC and DC input) were more efficient when idle (I expected the greatest efficiency to be when under load).

An AMD processor was chosen due in large part to the fact that chipsets in suitable motherboards used less power. For the CPU itself Intel had a competitive offering but no matching motherboard was power efficient enough (from page 7).

Page 8 documents how using a cooling fan (instead of passive cooling) reduced the power requirements of the CPU to such a degree that it always saved power use overall. Why do CPUs take less power when they are cooler?

Page 9 mentions that a small passively cooled video card can draw 88.5W when idle! That sucks pretty badly, it seems that having a video controller integrated with the motherboard is the way to go if you want to save power.

It’s interesting to note how much energy can be used by RAM. Page 13 shows that the difference between 2*1G and 2*512M can be as much as 3.4W and that the difference between different brands of RAM for the 2*1G can make as much as 1.2W difference. Their final system drew 61W when idle, my latest 64bit system takes 52W when idle [2] (which compares to the 38W of their system without a monitor), so we are talking about 9% of system power being saved by using less RAM or 3% being saved by using a different brand of RAM.

The summary of hard drive power use on page 14 is interesting, the fact that 2.5 inch laptop disks use less power than 3.5 inch desktop disks is hardly surprising, but the difference when idle is very surprising (apparently one of the 3.5 inch disks spends 8W on turbulence and friction in the bearings). It’s unfortunate that they didn’t compare any of the server-class 2.5 inch disks, it was about 6 months before the article was written that HP announced that in future they would cease shipping 3.5 inch disks and only use 2.5 inch disks (I wonder if this is related to all HP’s recent work on server cooling). Rumor has it that many server class 3.5 inch disks have platters that would fit into a 2.5 inch case because at high rotational speeds a larger diameter platter would not be strong enough.

The information on DVD power use on page 15 is quite shocking. From now on when I install machines as servers which don’t have a need for for a CD-ROM drive I’ll remove the drive prior to deployment. Even if it saves only 0.47W then it’s still worth doing on a machine which uses less than 40W! An additional benefit of this is that it might speed up the boot process as the system won’t need to check for a bootable CD.

It’s unfortunate that most computer parts don’t have published documentation on how much power they draw. Even if you don’t want to run on solar power there are still significant benefits to saving electricity (including reducing the noise from cooling fans and heat problems in summer). If technical data was published then people could make informed decisions about which parts to buy.

Update: Changed the percentage savings for different types of RAM to be based on the system power use without the monitor. I’m most interested in saving power for servers and for idle desktops (running a desktop machine 24*7 is pretty common) so most of the time the monitor will be turned off.

It’s interesting to note that they power their system uses is about the same as a P3 system and could be less if they used a different hard drive.

Fried Food

I’ve just been reading about oil deterioration when deep frying [1]. Apparently frying food can cause the production of Acrylamide [2] which causes cancer, is a neurotoxin, and does other bad things to your body. Deep frying in a vacuum [3] is a solution to this problem as the lower temperatures reduce the formation of the bad chemicals (and also increase the life of the oil thus making for cheaper fried products). Of course this means that deep frying in a pressure cooker as KFC does probably gives a result that is a lot worse for your health [4].

For some time I’ve been avoiding KFC due to concerns about the treatment of the chickens. I have been regularly eating fried chicken from a local store which looks and tastes very similar to KFC so presumably is cooked in the same way. I guess I’ll have to stop eating that now.

I wonder if toast is also bad in this regard. I expect that sausages would be a problem when cooked on a BBQ.

In other health news I’ve been reducing my meat consumption and I’m considering trying to entirely avoid farm raised animals to restrict my meat consumption to game meat, this should be good for my health and is also a lot better for the animals and the environment.

Car Sharing in Melbourne

Recently I noticed that some parking spots in the city area are reserved for car sharing. There seems to be two car sharing companies operating.

Flexicar [1] costs $50 to join, has a $10 per month membership fee (which includes one hour of driving at a value of $12), and costs $12 per hour or $80 per day to drive a car plus $0.15 per Km if you drive more than 100Km in a day. They also have pre-paid plans which bring all the guesswork and complexity of mobile phone bills to car rental. Also they give discounts to members of the City Rewards [2] program which are greater than the membership cost, so anyone who plans to join them should join City Rewards first.

To use a car you phone up or use their web site to make a reservation. Then you find the car you reserved at it’s designated location and swipe your card across the windscreen to unlock the doors (presumably it’s an RFID card). The glovebox has the key for the ignition as well as fuel cards for any fuel you use a BP, Shell, and Caltex petrol stations (presumably if you run low on petrol when not near those ones you end up paying). All you pay is the rental rate and any tolls for toll roads you use.

When someone doesn’t return the vehicle to it’s designated spot on time there are penalty rates, which may include the cost of a taxi fare for the next person who had booked it.

It seems like a really good idea that can save significant amounts of money for people who live in the central areas (the costs of maintaining and insuring a car are significant, as is the depreciation on a new car as an asset).

The competitor is Charterdrive [3] which costs $25 to join (less than Flexicar but the same once you consider the discount), the same $10 per hour for 8:30AM to 5:30PM hours, and then cheaper rates for evenings and weekends. $25 for a night (5:30PM to 8:30AM the next morning) is good value if you want to drive home from work and then return the next day (if you work late then you might expect to pay $30 or more for a single taxi ride to get home). The weekend rate of $90 for 5:30 Friday to 8:30 Monday is also quite competitive, I expect that there are many people who only use a car on the weekend who could benefit a lot from this. $90 per weekend for 40 weekends a year (some weekends you would stay home or just use public transport) is $3600, insurance, registration, and basic maintenance of a car that you would want to own would cover most of that. Charterdrive does charge $0.20 per Km though for all journeys (with a discount rate of $0.15 per Km for long journeys on some plans), as opposed to Flexicar only charging $0.15 per Km for distances in excess of 100Km per day.

Charterdrive seems to be a newer company and has a far smaller presence. But it’s business model seems a little different and the focus on renting cars for people to drive home means that some people might benefit from being members of both companies. The $0.20 per Km makes Charterdrive more expensive more expensive for most city use, and the discounts offered for Flexicar seem to make it cheaper for use during business hours.

Charterdrive states that they have a deal with Red Spot Car Rentals [4]. It is not stated on their web site if you want to use one of their cars and they are all in use, I wonder whether a Red Spot car would be provided for the same price. Flexicar however claims that they aim to have a ratio of cars to members sufficient to make such things unlikely. Maybe it would be prudent to join both organisations so that if one had no vehicles available then you could use the other? In one city car park that I often pass the Flexicar and Charterdrive parking spots are adjacent so there would be no difference in convenience in terms of which one you use.

I wonder whether they will continue getting adjacent spots. If many people join both organisations then it would be more effective if they don’t get adjacent spots to get better aggregate coverage. I think that at the moment the main challenge for both companies is to grow the popularity of the car-sharing business. I expect that the real competition for who gets the biggest slice of that business will happen in a few years time.


There is another Australian car-share company in operation named GoGet [5], interestingly I discovered their existence when I reviewed the Google advertising on this post…

GoGet has a significant presence in Sydney, a small presence in Melbourne, and is only making a start in Queensland. Their hourly rates are significantly lower than the others (as little as $4.40 per hour) but distance rates are as high as $0.35 per Km. One significant benefit is that they have plans for two or three drivers which could allow an entire family to sign up on one account. If you drive less than 20Km in an hour (which would not be uncommon in city driving) then GoGet would be cheapest.

A Bio-fuel Petrol Station

Today I happened to see a bio-fuel petrol station! I decided to check it out (even though I was traveling by tram in a part of town that I don’t normally visit so there was no possibility of any real purchase).

The station is Conservo [1]. Their main products are E10 petrol (10% Ethanol and 90% Petrol), B20 bio-Diesel (20% bio-Diesel and 80% Petroleum based fuel oil), and B100 (100% bio-Diesel). All the fuel that they sell has a biological based component. The prices for the fuel seemed a little lower than is charged by other petrol stations, but it’s difficult to tell as fuel prices can change rapidly.

I spoke to one customer who had just filled up his 4WD with bio-Diesel about his experiences. He said that he sometimes used B20 and sometimes B100. He had found no down-side to using such fuels but had noticed that when under hard acceleration the bio-Diesel fuel seemed to cause less dark smoke (IE less soot).

All the fuels that they sell are produced in Australia. There are issues with imported bio-fuels which are sometimes produced with slash and burn agriculture and often increase the prices for essential food items (such as corn in South America). As the fuel is produced in Australia such issues should not apply. According to a brochure they have facilities to allow people to deposit used vegetable oil which can then be converted to bio-Diesel.

Inside the store they sell a variety of organic foods and drinks, I bought a bottle of carbonated organic apple juice which was quite nice and at $3 was not outside the price range that I expect from a petrol station (which do tend to charge high rates for refreshments). It was not an unreasonably high price for an organic drink.

In the store they sell and promote a range of product that are positive for the environment. They have a display about using algae to produce bio-Diesel fuel which has some interesting information but unfortunately didn’t list the productivity of algae fields in terms of the number of tons per hectare per year (or month or other time period).

One really interesting point I read on their web site concerns the flash point [2] of fuel. The flash-point is the temperature which allows enough of the flammable substance to evaporate to produce an ignitable mixture. Petrol is listed as less than -40C, fossil-Diesel fuel is greater than 62C according to Wikipedia (greater than 55C according to Conservo) while Conservo list the flash point of bio-Diesel as greater than 110C. Wikipedia lists the flash point of canola (rape seed) oil as 327C. This is described as being a benefit of bio-Diesel. While it’s obvious that this is a disadvantage for Petrol, I find it difficult to imagine a situation where a fuel tank could reach a temperature greater than 55C but less than 110C.

In their Good for the Environment [3] page they claim that the exhaust from burning bio-Diesel is less harmful to human health than that from burning fossil fuels. My previous post about Vegie Cars [4] is getting some comments suggesting otherwise. So far I haven’t found good references either way, but the discussion has raised some really good issues.

Update: Petrol’s flash-point is less than -40C not +40C.

Vegie Cars

I’ve read a lot about running Diesel vehicles on plant oil, but one thing that was never clear was why some people claim that you need special chemical additives.

Their site is very interesting and has some good technical information, even if you never plan to drive a Diesel vehicle it’s worth reading if you are interested in cars.

I’ve read a lot about running Diesel vehicles on plant oil, but one thing that was never clear was why some people claim that you need special chemical additives.

The article about converting vehicles to vegetable oil on the [1] site explains all this. It seems that if you want to produce fuel which can be used in unmodified vehicles then you need to add a mixture of methanol caustic soda. This is going to be difficult, dangerous, have some expense, and probably not be that good for the environment.

The other option (which they recommend) is to modify the vehicle to accept straight vegetable oil. This means pre-heating the oil before it enters the engine (to lower it’s viscosity and make it vaporise more easily) and to filter the oil to remove solid objects and water.

A possibility is to have two separate fuel tanks so that you can switch between plant oil and petroleum based Diesel fuel. This is an option if driving in a cold climate (probably not an issue in Australia apart from a few mountains) and if you are concerned about the quality of your plant oil (a bad batch could clog the filters and force you to use petroleum based fuel).

They also have an interesting cost-comparison page to show you how much money you might save by using plant oil [2].

Their site is very interesting and has some good technical information, even if you never plan to drive a Diesel vehicle it’s worth reading if you are interested in cars.