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Using resources twice over to save money

“Directly integrating a small to medium amount of green electricity into a factory is quite simple. In some countries however, the legal framework needs to be changed if the manufacturing sector is to adopt renewables more widely”, says Spanish analyst Anibal Reñones Dominguez

Over the last four years, three factories in Spain, Italy and Turkey have been testing novel solutions to show how it is possible to cut energy bills and use fewer resources while maintaining productivity. Performed in the food, foundry and textile industries, the experiments are now set to be upscaled in the same fields.

Anibal Reñones Dominguez, deputy head of the Systems Division at the Cartif Technology Centre, and coordinator of the European project REEMAIN explains how these results were possible by recovering the lost energy, optimising production and integrating renewables.

 

How do you appreciate the overall outcome of the project (1 October 2013 - 30 September 2017), now that the tests are over?
It was a good opportunity to interact with the factories and inform them about the experiments and the energy efficiency outcomes. Usually factories outsource energy saving measures. Under REEMAIN, we engaged with factory managers from the outset and involved them in the selection and design process: they were shown the different technologies and range of energy efficiency solutions; they could make their own decisions according to the technologies’ return on investment and level of innovation. I would like to emphasize that this is a demonstration project. When it ends, we will provide an unbiased evaluation and will recommend in full honesty the best technology for each factory.

 

What kinds of energy saving technologies have been tested in each industry?
We did several demonstrations in each industry. We suggested cookies producer Gullon use the outside cold air to produce cold water in a sustainable and efficient way. Therefore, the factory could obtain its own cold water for different stages of the production process, such as cooling the biscuits after removal from the baking ovens or providing air conditioning for the rooms where the chocolate or creams are applied. This would save electricity and be an environmental friendly solution.

The biscuit factory is located in the Northern Spain, where the temperatures are low enough during the cold seasons. Biscuits are food products which need to be kept dry and at cooler temperatures. Factories usually prefer a simpler, although less sustainable, electricity-based cooling water system instead of a more complex system capable of drawing on outside renewable resources.

Another example is the recovery of the wasted heat from the baking oven chimneys. This can be used to preheat the ovens instead of using natural gas.

At textile factory Bossa, in Turkey, we tested the impact of using organic raw materials such as cotton and indigo dye in the manufacturing processes. We also tried to make the residual waters from the industrial process more ecological.

The textile industry requires a lot of water, especially for dying the denim fabrics. To neutralise the waste water before releasing it into the nature, the factory’s workers used to add sulfuric acid. We suggested carbonic acid instead, which is more ecological. It avoids the formation of salts in the treated water, which is what happens when using sulphuric acid. The factory now plans to capture CO2 from the boilers and use it to treat water.

The foundry is a typical example of where a lot of energy is used for melting iron. The exhaust fumes from this process are very hot (400-600 degrees Celsius) and the industry must cool them down before they are released into the atmosphere. We suggested SCM Group Spa – Fonderie use this heat to produce thermal water. In possibly a couple of years, this thermal water could go onto heating the local district or the factory’s own purposes.

 

Which technology was the most “challenging” and posed the most difficulties during the tests?
The heat recovery from the cupola furnace of the foundry in Italy was a great challenge for us. The high variations in temperature and the exhaust fumes put a lot of pressure on the heat exchanger, which has to recover as much heat as possible.

Current foundries need to release energy to cool down the furnaces’ exhaust fumes. Once the exchanger technology is ready, it will have a huge impact on foundries’ energy bills. It will be used to generate hot water directly from the exhaust fumes and it is expected to capture more than 50% of the wasted energy.

Renewables also represent a challenge, albeit a more general one. Technically, it is quite straightforward to directly integrate a small to medium amount of green electricity into a factory. However, in some countries such as Spain, the legal framework needs to be changed if the manufacturing sector is to adopt renewables more widely. Due to high costs and legal uncertainties, we are not able to integrate renewables as much as we would like.

 

The project’s team have also developed a “Decision support tool” which helps managers to better analyse the alternatives and to enhance efficiency. Could you tell us how this tool works and what kind of information it gives to managers?
This is a software tool which can model the interdependencies between buildings, surroundings and the manufacturing production system (energy and material flows). It is applicable to any kind of factory and uses data about the factory’s equipment, energy used, enveloping materials of the walls and the factory’s production background. Once this data has been entered, the software analyses the factory’s working profile and provides managers with preliminary advice as to where they may save energy and resources.

Different solutions of various sizes, such as applying a solar roof, can be simulated. The tool can make long-term calculations to see how much energy is generated in this case. Users can also combine virtual solutions and accurately estimate return on investment.

 

Can the solutions tested within this project be used by other sectors?
Sure, a cooling solution based on renewable energy could be applied across many food sectors, where cooling systems are needed in the processing chain. Also, the technology we tested for heat recovery can save a lot of energy in industry. We are drafting a plan to replicate the REEMAIN project’s demonstrations and are calculating their impact in other more or less similar sectors.

 

What suggestions would you make to managers for them to successfully compete in an increasingly tough market while remaining environmentally friendly?
We would suggest they read our best practice book, as it gathers interesting practical examples we experimented during the project. It shows managers where and how they could save energy, and how to improve production.

By examining different situations and points of view, managers are more able to notice issues or inefficiencies in their own businesses. Factory building shells, technical building services and manufacturing systems are not properly integrated with one another and knowledge does not flow enough. Therefore, the design stage of an efficiency measure must look at the factory as a whole, taking into account all systems and surroundings, interactions and requirements.

Surprisingly, the installation of energy efficiency measures has revealed many small inefficiencies and mismatches in the existing measurement and control systems. The fact that one system provides the required services (e.g. hot water) does not necessarily mean that it is performing in the most efficient way.

 

By Sorina Buzatu

31 July 2017