Archive for the ‘tinkering’ Category

Decisions, Decisions!

January 26, 2011 3 comments

I have mentioned before my little Scoobi car, a Subaru Justy. It is a nice little car, economical to run and quite nice to drive. It is a bit tatty, but looks do not detract from the ability of a car to get me from where I am to where I want to be. And this car has four-wheel drive, which was very useful during the snows last year.

Peugeot 306 MeridianBut I have been offered a Peugeot 306, 1998 model. It is a year newer than the Scoobie, a bit bigger, more comfortable and a lot tidier. It has been standing for over a year, so there is no MoT, VEL and the battery was rather non-responsive.

I now have the car at home. The battery is charged but the car misfires occasionally. The electronic odometer doesn’t work and I need the code to get the in-built radio working.

Being a 1600cc petrol engine, the car attracts a higher rate of VEL than the Scoobie and I guess the fuel consumption will not be as good. Insurance may be higher as well.

But, it is a lot tidier, much more comfortable, and that little bit bigger, meaning that I do not have to struggle to get Mum’s wheelchair in the boot.

So, this is my dilemma. Do I keep the very cheap-to-run Scoobie, or go for the newer, more comfortable and more expensive-to-run Pug?

Oh yes, and the Scoobie has a non-standard exhaust system which I have to weld up from time to time, whereas the Pug is standard in every way.

I always dread the sound that precedes the Scoobie’s exhaust falling apart, but it is not worth getting a new standard system. It would cost more than I paid for the car!

So, I could sell the Pug for the owner and receive a 10% commission on the sale, or sell the Scoobie and pay for the Pug for myself.

Of course, the Pug might fail the MoT big time, in which case there will be no decision to make, but I cannot find much wrong with it, so I think it will get through.


My Little Car

June 13, 2010 3 comments

If you have read previous posts, you will know that I swapped my Mazda Bongo, 8-seat MPV for a Subaru, not a rally-winning Impreza, but its smaller brother, a Justy.

Subaru Justy 1.3Although it has been well abused by previous owners, this brave little machine is still going strong. In fact, we drove a 200 mile round trip last weekend.

It is not the most comfortable car in the world, having a very short wheelbase,  rather stiff suspension and small wheels, but it did not cripple me in the same way as some small cars do. The exhaust is noisy, due to the non-standard rear box fitted (and re-fitted after it fell off). But it is at its worst at 3,000 to 3,500 rpm at full throttle. I rarely use full throttle.

It cruised happily at 70mph down the many motorways I drove along last week, and most important, is used less than £20 of petrol. When I had previously done this same trip in the Bongo, it cost me £40 in diesel, so I am happy.

Most importantly, I checked the oil level at the end of the trip and the car had not used any.

There are still little DIY jobs  to do on it, which I will get around to one day, like fixing the dash lights, which don’t work at the moment, fixing the driver’s door window, which doesn’t work properly, and getting some more fixings to stop the interior trim from vibrating.

So, after a couple of months, I am still very pleased with my little car.

Categories: Cars, tinkering Tags: ,

Methane -v- wood/kerosene/charcoal

May 13, 2010 3 comments

Even if KCIS could design a very cheap anaerobic digester, would Kenyan women adopt it as a cooking fuel?

Wood and charcoal are traditional fuels, and I believe that Kenyans follow their traditions unless they are given a very good reason not to.

So, if KCIS did develop a very cheap anaerobic digester, would anyone use it?

OK, dear reader, please discuss!

Cost -v- Efficiency -v- Availability

May 5, 2010 3 comments

When building an anaerobic digester for use in poor, rural communities in Kenya, the first concern to be addressed must be safety – obviously. We are producing a flammable gas and using feed stock that could contain all sorts of bacteria.

With that issue in mind, the next two issues are efficiency and cost.

In our first full-size digester, we used a 45 gallon oil drum 970mm high x 580mm dia), into which we put cow dung and water, leaving a gap at the top of only 25cm. Once sealed, the top of the drum quickly domed under pressure, but it has always managed to hold the pressure.

But we realised that we either needed an expanding digester tank or a gas storage facility.

The major expense when building an anaerobic digester is the container(s).

In Kisii, a single 45 gallon oil barrel, with two threaded outlets in one end (2″ and 5/8″) costs Ksh 2,000 (£17.25). (I can buy these in the UK for £6.20 or Ksh 720).

The ideal, which I have not been able to source in Kisii is a drum with a lid and clamp:

45 gallon drum with lid and clamp

Smaller plastic, cylindrical  water tanks cost a little less, but would not hold pressure, so two would have to be used to make an expanding tank, or a digester and storage tank.

When I started on this and similar projects, I imagined using scrap or discarded materials. Unfortunately (for us), there is very little useful scrap in Kenya. It is all used by the locals. Nothing is left to waste, and if someone does find something discarded, they will recuperate it for possible use at a later date.

That has dealt with cost, to some degree. What about efficiency and ease of use?

With a good anaerobic digester, all the user needs to do is turn on a gas tap and light the burner. But after about six months of use, the digester needs to be emptied and refilled. It then needs to be allowed to re-boot before any usable gas is produced. This can take up to a week, depending upon the weather in the area. In Equatorial Africa, this could be a couple of days.

Then there is the question of actually emptying the digester. The 2″ hole in the end of a 45 gallon barrel is not ideal, either for loading or emptying. Plastic water storage containers, with their large opening in the top would make this task a lot easier.

However, if the standard oil drum is to be used, I think that it should be horizontal with the 2″ hole as low as possible.  The drum would receive more direct sunlight and it will be easier to empty – probably.

I still believe that the best  and safest design is our Mk II comprising two drums (digester and storage) and a header tank to provide pressure, water scrubbing and a safety outlet should an excess of gas be produced, but this model would be expensive.

The cheapest, using only one drum, is not efficient.

The Mk II would suit commercial environments, hotels, safari camps, etc., as they can afford a little outlay to produce what is effectively a free fuel that can be used for cooking and water heating.

So, it is back to the drawing board and calculator when I return to Kenya.

Just Wondering …

May 2, 2010 1 comment

I wonder if the anaerobic digester (see previous post) would be more efficient if it was laid on its side. After all, it needs heat and, on its side, there would be more surface area in direct sunlight, wouldn’t there?

It would certainly make it easier to remove the sludge as and when the digester is exhausted and needs to be recharged with new feed stock.

Oh well, I suppose there is only one way to find out …

Building an Anaerobic Digester

April 30, 2010 17 comments

We have built the simplest of anaerobic digesters to prove the theory. We did not follow any of my designs due to cost constraints, but have built it so that it can be improved later.

Searching the market for fittings

A locking tap for the outlet

This is what we used for the feed stock

Getting it into the drum was messy

Sealed up and ready to start producing methane

A balloon shows that gas is being produced.

Local resident, Junior, wants to know all about it.

Of course, little boys love smelly gas, the smellier the better.

We're cooking on gas!

We intend to add a storage drum with a water-filled header tank to provide a near constant pressure.

Going back to Physics Classes of the 60s

April 30, 2010 Leave a comment

Now that’s a long time ago, but I remember clearly (I think) a physics lesson in which I learned that capillary action  and evaporation of water could make a food cooler.

The equipment was a saucer and a clay pot. The pot has to be porous to allow water to rise up the sides by capillary action where it would evaporate. The theory was that the water, in order to evaporate needs to pinch heat from somewhere and it took it from the interior of the upturned pot. Anything inside the pot was thereby kept cooler than ambient temperature.

Sounds good, easy and cheap.

The last time I was in Kenya, I tried to find a suitable unglazed clay pot with no success, but I was since told that we do have access to a clay pit, so I may be trying my hand at “throwing” a clay pot (is that the right word?), and firing it.

While I am at it, I want to make a clay oven, not for cooking pizza, although that wouldn’t be a bad idea, but to use to roast a chicken.

It sounds like my next visit could be messy, but then, so was the last one, trying to pour cow dung into the 2″ hole in the top of an oil drum.