Feature

Environmentally friendly car manufacturing gets a facelift from Ford

Dr Garth Cambray

Every now and then you read something really funny - for instance, 280 000 Ford F150 pickup trucks (probably one of the better icons of excessive fuel consumption) per year, are made in the most environmentally friendly factory on Earth. Yes, the Ford F150, which gives 4.2 kilometres to the litre is made in a more environmentally friendly factory than the Daimler Chrysler Smart car which gives you 28 kilometres per litre. Working on the US average of 46km travelled per day this means that the F150 would use 4000l of fuel a year compared to the Smart's 590/year. There are many things you can do with an F150 that you cannot with a Smart, but we all know the biggest load most of these trucks normally carry is a few bags of shopping, a small toolbox or a dog.

Ford has however done some good homework to give this gas guzzler's image a face lift. If other more environmentally friendly vehicles were produced using similar technology, it would definitely make the world a better place.

Fumes to Fuel

Just about all of us have had the misfortune of having to paint something in an enclosed space and have learnt that the solvents in paint, so called volatile organic compounds (VOCs) can turn the atmosphere in the room foul and give you a bad headache. For the global motor industry, which uses 32 000 000 kg a year of VOCs, releasing these compounds into the environment is illegal, and as such expensive methods are used to collect both the solvents used in the painting process and the small misty overspray particles of paint that don't stick to the vehicle. It is safe to say that the car painting process gives the motor industry a headache.

For many vehicle manufacturers the methods used to reduce the cost of VOC recovery result in lower quality pain jobs as some coats of paint are applied with water borne paint. These water based paints give lower quality finishes, but are easier to deal with environmentally.

The average VOC molecule contains a lot of residual energy. It will generally consist of a carbon backbone of some configuration and a range of other molecules such as hydrogen and chlorine bonded to this backbone. Breaking these bonds can reduce the VOC to simpler molecules which are less environmentally damaging, such as carbon dioxide and water, and can in the process, if the reaction is carried out in a fuel cell, generate electricity.

Ford motor corporation have developed a suite of technologies which allow the application of high quality paint finishes using specially formulated VOC based paints. The paints are formulated in such a way that a high load of pigment is carried per unit volume allowing a small amount of paint spray to cover a lot of the car. The VOCs used as solvents are specifically chosen so that they can be collected and passed through a fuel cell power plant that generates electricity for the factory. The technology allows cars to be painted three, as opposed to the normal five times. This saves costs, time and results in less emissions.

The electricity generated by the fuel cell plant at the Ford Dearborn plant feeds back into the power grid of the factory. Fumes from the painting process are gathered and concentrated using membrane technology. Fuel cells work by combining hydrogen and oxygen to form water. The reaction is facilitated by catalysts and is driven through a membrane, generating an electrical current which can be used. However the catch here is that hydrogen and oxygen are required - oxygen is readily available in the air. However, it is necessary to strip the hydrogen from the VOC to allow it to work in the fuel cell. This process is carried out in a reformer. In the reformer the VOC, in the presence of a catalyst system, is reacted with steam to produce hydrogen and carbon dioxide and depending on the other molecules in the VOC, various trace contaminants. The hydrogen is then separated from the gas mixture and channelled to the fuel cell where it generates electricity and water.

At full production the Dearborn fuel cell power plant generates 55 kilowatts 24 hours a day. The alternative to the fuel cell plant, incineration of the VOCs would require 350 kilowatts 24 hours a day. All in all this represents a positive saving to the environment, and also the consumer who gets a better paint job at a lower cost.

Another big problem in the vehicle industry is overspray - the small aerosol mist particles of paint that don't actually hit the car. These drift around and have to be filtered from the air and then are placed in receptacles and dumped in landfill sites. Paint is expensive, so to dump it in a hole in the ground is sad financially and environmentally. Again, Ford have developed a system where overspray is taken and used to make a sound dampening compound which is placed near noisy parts of the vehicles, thus allowing another waste to be reused and saving money and the environment at the same time.

Big roofs make big impacts

If one pictures the average piece of land, it contains many mechanisms that absorb water and when rain falls, the water is encouraged to soak into the ground rather than rush away to the rivers and sea. If one builds a factory on such a piece of ground the amount of time water will stay in that spot is reduced as water generally runs off roofs and tarmac very fast. Again, Ford have excelled in their efforts to minimise this environmental impact of their Dearborn plant by turning the entire roof surface area of the plant into a low maintenance living roof.

The roof surface area has been covered in a special layer of 8cm thick mats containing drought hardy plants of the Sedum genus. The mats are made with a lower root stopping membrane followed by a specialised drainage layer and then a blanket in which the roots of the Sedum plants can grow. Plants of the Sedum genus are drought tolerant and are commonly used as ground covers in rockeries around the world. As a roof cover they are low maintenance, requiring no trimming or mowing and are quite pretty.

When rain falls on the roof, instead of rushing off in a big pulse, it is retained in this semi natural roof sponge and runs gradually off the roof. From here it is channelled through a series of recreated wetlands and other water storage facilities so that the rate of runoff from the surface of the factory resembles that of a conventional natural piece of land - or possibly slightly better, a proper wetland.

In addition to slowing water runoff, it is important to remember that the roof consists of plant matter, which absorbs some of the Suns energy and converts that to sugar and stored carbon compounds. The water absorbed by the roots is slowly released into the atmosphere by the plants cooling the roof. So in addition to the aesthetic beauty of a living roof, the whole set up conserves energy by reducing cooling costs.

This is very impressive and a sterling effort on behalf of Ford and once again, the corporation that pioneered large scale vehicle manufacture is leading the way in environmentally friendly factory design (other than the fact that the factory makes the gas guzzling F150 that is).

To see how local African car manufacturers shape up we asked the following questions:

How does your company deal with volatile organic compounds from your paint shops and how much does this cost per year?

What pollution control measures has your company implemented to reduce its impact on the environment, and which of these are you the most proud of?

Ford SA, BMW SA, DaimlerChrysler SA, Volkswagen SA, Toyota SA and Mazda SA were contacted, however no responses were received at time of press.  Should any of these companies reply at any point we will add their answers here.

Science in Africa - Africa's First On-Line Science Magazine

Copyright  2002, Science in Africa, Science magazine for Africa CC. All Rights Reserved

Terms and Conditions