DIGIVU Combined Blogs » .Green Things

Freeze Concentration – Equipment Series

admin — Mon, 02 Jan 2012 12:13:27 +0000

A while back I wrote about pressure processing which was driven by the “fresher flavour” of juice that is not heated. Freeze concentration is driven by the same quality concerns and is an alternative to concentration by boiling off water.

click the image to visit the website

This article from the Institute of Food Technologists covers freeze concentration in a few pages giving information on the process and discussing the advantages and disadvantages of the technology

Interesting is that the energy needed to melt a kg of ice is several times lower than that required to evaporate a kg of water. In these days of high energy costs and carbon footprints this would seem to be an advantage. However, the freeze concentrator can not be run in mutiple effect plants which allows an evaporator with sufficient effects to use almost the same energy.

Even more disadvantageous, is that the freeze concentrator is often unable to reach the concentration required and a thermal evaporator has to be used as a finisher.

COP 17 – It’s Underway And …..

admin — Wed, 30 Nov 2011 13:36:09 +0000

I had thought I would follow what was happening at Durban online and find some interesting stuff on which to base a post. However, the amount of information is stunning. I downloaded an iPad app which pulls together all the information and found things like a 170 page report on emissions down to the level of dairy cow methane emissions on a country basis. But finding something relevant and interesting is more difficult. Things like President Zuma’s week address ( not like the determined political heros he opened with) and Canada’s threat to resign from Kyoto are in the news and don’t bear repeating here.

click the image to visit the website

So I thought this image of a web page might be more interesting. Walkers is a leading United Kingdom (UK) manufacturer of potato crisps retained the Carbon Trust to determine the carbon footprint of their crisps. Carbon Trust is a not for profit organisation set up by the UK government to “led on lows carbon technologies” who claim to save the UK £ 1 million a day.

They found that a 34,5 g packet of crisps produced 85 g of carbon dioxide. In comparison I found, for a post on bread buying behaviors in France, that a standard baguette produces 292 g of carbon dioxide. A bottle of cola has a carbon footprint of 340 g of carbon dioxide.

The pictures along the righthand side of the page represent the operations for which the footprint was calculated. Like most foods the footprint for the growing of the raw materials used, is a major part of the footprint in this case 36%. The most obvious excessive cost is packaging which makes up 34% of the co st and is normally significantly lower. The analysis indicates that there is no emission in the household. Many foods have high emissions in the household arising from cold storage and cooking costs as well as the effect of food which is inevitably wasted.

The effect of food waste on the carbon footprint is an issue that was previously not considered, but which it is now realised is very important. There seems to be a consensus that at least one third of the food produced is not eaten. This is accepted both in affluent societies where the loss is mainly in processing and the household and in developing/subsistence communities where it is mainly in storage and post harvest handling. The carbon footprint of the of the food lost is effectively added directly to the carbon footprint calculated for the food without considering losses.

Not only is the food lost, but all the inputs to produce the food is lost and must be reflected in the footprint.

COP 17 – Creates its Own 20 000 ton Footprint

admin — Mon, 28 Nov 2011 13:08:02 +0000

Those attending COPQ 17 are set to produce an extra 15 000 tons of Carbon Dioxide over the duration of the function.

click the image to visit the website

To put this in some kind of perspective this is about the same size as the carbon footprint of the territory of Saint Helena, Ascension and Tristan da Cunha and equal to around a month of Burundi’s footprint. From another viewpoint it is equivalent to something over 1 minute of China’s annual footprint or about equal to the anual footprint of about 900 US citizens.

All very confusing, but does it make sense for 25 000 people to travel, which is the major source of emissions, to “the other end of the world” to discuss how to reduce emissions? What would be the carbon footprint as well as the effectivity of doing this by alternate means of communication. PS just for those who might wonder, my very simplistic view of a carbon footprint and why we look at it is:

The carbon footprint is a quantitative measure of gasses released into the atmosphere that create a greenhouse effect
The greenhouse effect results in a rise in the atmosphere’s temperature&nbsp
A rising atmospheric temperature has many effects including more variable weather, water level rise and changes in farming environment&nbsp
These effects are negative for the future of the world

A previous DIGIVU post, reported a clever graphics which presented the carbon footprint of a number of foods in a graphical form. Have a look at this, it’s really informative.

Indigenous Plants in the Preservation of Smoked Fish

admin — Sun, 27 Nov 2011 09:11:35 +0000

This is another great article from the African Journal of Food, Agriculture
, Nutrition and Development.

click the image to visit the website

It further promotes the potential of the chemical ingredients of indigenous plants. The study clearly show that Piper guinensis is the most effective within the experimental setup.

It would, however, be nice if there was a bit of information about the nature, dosage and availability of Piper guinensis. A quick look at Wikipedia indicates that it is a strong pepper like spice that would produce a spicy fish which might not suite all and that it is rather scarce and highly valued.

But very encouraging and worthy of some feasibility evaluation.

A COP-17 Inspired Look at Carbon Footprints in Food Chains

admin — Thu, 24 Nov 2011 14:09:39 +0000

With the United Nations and many of the world leaders in climate change on their way to Durban for COP-17, I think it might be worthwhile focussing on some Food Chain and Food Processing Issues that effect the carbon footprint of the food we eat.
There is no lack of information and discussion in the area, so I will not be trying to give you a full picture, but rather I will present some of the things that interest me and maybe identify places you can go to get information.

To start if off I suggest you have a look at this paper, that was publicised 5 years ago when the whole let’s not import food from afar was first voiced and seemed to make sense.

click the image to visit the website

The first think that strikes the reader is the complexity of the analysis necessary to evaluate the carbon impact of a food product sitting on the plate of the consumer. Not only are there a whole range of possibilities but all activities in the Value Chain need to be considered in detail. One of the most complex issues that makes the comparison of data very difficult is where is the boundary drawn within which the carbon foot print is calculated – must the evaluation go back to the mining of the iron ore which was used to make the steel that forms a filler valve?

What this and a study of the document clearly shows is that it is most likely to make simple comparisons without fully understanding all value chains. even then one may worry that it’s too easy to “pull the wool” over the readers eyes in defining how the carbon footprint is evaluated in any particular case.

This obviously makes the simple “mines better than yours argument” impossible to make without detail investigation and infant many counter intuitive results have allready been identified by detailed like cycle analyses.

The conclusion and recommendation of this report, on only a small sector of the food industry, are rather disappointing as they are rather imprecise identifying many valid issues and needing to call for “much more study”.

An interesting comment in the paper, was that the carbon footprint is probably closely related to the perishibillity of the product. This since cold chain operation, transport and cold storage as well as their effect on waste are all big factors in the emission of green house gasses.

Finally, for technologists and scientists it’s important to note that reductions is ghg emissions are probably just as likely to come from behavior change as from new technology.