This Australian article shows the state of the art in biogas recovery and consumption.
While biogas has been around and used for centuries, this plant focusses on increasing the sustainability by controlling the anaerobic digesting more efficiently and managing the gas storage and consumption.
The “Green Energy Orb” is just a methane storage tank, but then greenwashing is allowed!
click the image to view the paper
This is a video published by Tetra Pak, that describes research they undertook to establish whether the standard fruit juice pasteurisation conditions could be reduced to save energy while still guaranteeing shelflife and avoiding product “damage”.
They found that, for orange juice, the second pasteurisation could be reduced from 95C for 15 seconds to 80C. This reduces cost of energy for orange juice filling at 22 000 l/h over 500 shifts a year by 19% and carbon footprint by 20%.
They also found that the across plate temperature difference could be increased from 5 to 20C. This would have significant impact on the heat transfer surface required and hence the capital cost of the pasteuriser.
Papers describing food drying techniques normally list the obvious contamination risks of drying in the open air as a major disadvantage and and based on this dismiss its application. However, the large volumes of food that are sun dried every year and the savings in energy and capital bely this quickly reached conclusion.
Searching the literature and regulations doesn’t give any guidance on the advisability of establishing a new sun drying business.
However, the two videos below show the large scale use of sun drying and the associated technologies applied at Cecilia’s Farm, near Prince Alfred in South Africa.
It seems that the critical point about the sun dried business they run, is that all fruit is washed before further processing and or packaging. Arguably this makes it comparable to fruit which is often not peeled, packaged salad and leafy vegetables. These are grown in the same environment and simply washed before eating.
The massive advantage of sun and to a lesser extent solar drying is that they produce shelf stable foods with minimal environmental impact and low processing and packaging costs.
Small scale farmers in rural areas with a a few cows can easily produce more milk than their family consumes, opening the opportunity to earn income by selling milk. However climate, lack of reliable energy and long distances make this an unreliable business. Introducing standard fresh milk handling technology does not work because of the costs are too high, the quantities too low and energy too unreliable. Other solutions such as increasing shelf life with fermented products and introducing the Lactoperoxidase System have there place but there is real demand for fresh milk.
This new system being introduced by Promethean Power could change this.
click the image to open an online story
This is a mechanically simple system that is powered by local electrical supply which does not need to be consistent or reliable. Whenever electricity is available it is used to “charge” a thermal storage system, the system is then used to cool milk whenever it is available.
The thermal storage system consists of a cylindrical stainless steel tank, containing an unspecified phase change chemical in a heat transfer fluid. When electricity is available it is used to refrigerate the tank, freezing the chemical which absorbs large quantities of energy as it changes phase.
The simplicity of the system lies in the design of what they have termed the Rapid Milk Chiller. The milk is distributed on the top of the stainless steel tank, it flows over the total surface of the tank and is thereby cooled quickly. With gravity transferring the milk there are no pumps, pipes and controls which would complicate maintenance, be difficult to clean and require electricity.
There is also the potential to use any other alternative energy source e.g. solar, wind, biogas and biomass which can be converted into electricity.
I like the idea and look forward to hearing about how it works out in practice.
I was amazed to find this technical note on Tetrapak’s website.
click the image to open the note
Since I first heard of Tetrapak in the 1970s I always saw them as highly technology and science focused and the leaders in liquid food processing. I and many others accepted their process design parameters without question. Now after all these years Tetrapak has the foresight and courage to question whether what has become normal practice is really the best solution.
They apparently asked three questions can the heat load in pre-filling pasteurisation be decreased, will a lower pasteurisation temperature result in product change and can a larger design temperature difference be used.
This interesting paper seems to answer positively in all respects and reports a 1.3 kg per 1000l carbon footprint saving which indicated we will be seeing changes in our plants.
Its true that “One Third of All Food Produced is Lost or Wasted” but it does get a bit boring when we hear it over and over along with a means of reducing it which is simple and obvious. This is made worse by the fact that these means of reducing loss are often very daunting and require actions that you have little effect on.
click the image to visit the website
This CTA briefing paper does a good job of summarizing the various places and ways in which these losses can be addressed. It for example shows that consumers in upper income communities need to take care of their actions and reduce losses – something that's hard for the individual to impact on and where no progress is evident. But we should all keep enthusiastic about it and do whatever we can to reduce waste even if our little effort is not going to be significant on its own.
As a Food Processor, a way of looking at this and keeping up the enthusiasm is to see the other benefits of saving food, which are not always considered. Whatever you do to reduce losses in you plant doesn't only reduce losses of food it
- Reduces agricultural input usage
- Increases sustainability of you business
- Saves you money, when the action required (as is often the case) does not require extra cost
- Reduces greenhouse gas emissions
- Reduction in water and energy consumption
I happened onto this manual just now and it got me to thinking about solar drying again.
click the image to download the manual
The document was prepared as a training manual for a Zimbabwian project funded by the Austrian Embassy titled Establishment of a production, sales and consulting infrastructure for solar thermal plants in Zimbabwe.
Its a comprehensive manual covering many designs and processes which you will see in illustrations from other documents you have read over the years. The 110 page book contains descriptions of many different dryers as well as examples of many different crops and their dryers. It also presents a great deal of technical data on drying but even though the title of the project nothing about markets, packaging and selling.
Solar drying should be all the rage currently giving its potential to impact global food shortage and climate change – but we still seem to be where we were decades ago.
If you are like me you enjoy getting a simple understanding of a food process/technology, even if you are never likely to use it!
(click image for full story online)
This is the case with this masters thesis, which presents a nice simple (two different levels of detail) explanation of the sugar cane process. It includes the two main juice extraction systems diffusion and milling in parallel, although I am not sure whether this often occurs in practice.
What at first glimpse seems to be a rather crude processing technology that produces mass market foods, is growing in the UK and seems to be attracting attention.
click the image to visit the website
At first glimpse it also appears to be an energy intensive process, but it needs to be compared to the energy input along the whole value chain and over time. I also needs to be seen as a cooking process, a preservation technique and as food packaging.
Some time ago I did a Google Plus post on a recent study that claimed the nutrition provided by canned beans was cheaper than that fom dried beans. I noted that this seemed unlikely and undertook to follow up on it. I contacted the author and received the paper on which the report was based. The reason was clear, in calculating the cost of nutrition from dried beans the cost of preparation time was included. This is the correct approach but the time calculated for dried beans was not just for the preparation and cooking, but included the hours that the beans were soaked in water. Canned obviously beans did not have such a cost included and the total cost worked out to be lower than the dried beans.
This just shows how careful one needs to be in these kinds of evaluations. Other issues that could be important when convenience, considering canned foods is the low cost of storage, the long shelflike and the reduced in home cooking needs. On the negative side the high cost of packaging and the limitations on the products that can be offered through canning.
I have always been a promoter of sun and solar drying, because they allow people to convert perishable fruit, often available at low or no cost during the season, into a stable product that can be stored until the next season at almost no or low cost.
This article provides some good information on the drying process, that helps in deciding how to actually dry.
The article is an in depth one and gives some really interesting data on drying rates. It compares theoretical with measured rates and is then able to model the progress of drying with this data. The graph below is a really clear indication of the main difficulty of solar powered systems – they only work for a part of the day.
This is particularly important in drying, were it means that sun drying carries on for 3 days. This is because, as the graph shows, drying actually only carries on for a fraction of the day. This fraction depends on the location. This is obvious, but for me only really became clear when I saw this graph!
This has implications for how you run your drying. First of all, it's no good having a nice social day picking, transporting, washing, selecting and preparing your fruit and getting it out into the sun in the late morning or even worse the afternoon. If you do you are going to need four days to dry. More importantly the fruit will be wetter at the end of drying on the first day and therefore more likely to spoil overnight. So rise early and get the fruit ready for the moment when drying can start. Secondly, because the whole drying period until your fruit is shelf stable is many times longer, the cleanliness and hygiene of the plant become more important to avoid spoilage and loss.
The two images in this post are from the online journal at http://www.ajfand.net/Volume12/No7/Mercer11020.pdf