What does energy efficiency mean?

Here are some examples of interventions carried out by three organizations in order to cut energy costs successfully

By S. Gorla – Energy Manager PSA Peugeot Citroën

During our daily routine we constantly use and transform energy. Nowadays humans’ activities are growing more and more with a consequent increase in the energy employ and, of course, in the energy costs which badly affect our social life as well as the environment. If you want to bring a nation to his knees, you just need to turn off the master switch power and the gas switch. Everything would stop working and the whole country would slowly fall into destruction. Here is an overall view of the world energy situation: global population has reached 6,7 billion people (300,000 babies born per day). Over the past 10 years the population has increased by 12%, the primary energy by 20% and the electricity by 30%.

But what do you exactly mean by being energy efficient?

Saving energy means reducing consumption and wastes thanks to a more intelligent use of energy. Today we are more and more aware of the advantages of an eco-friendly behaviour. Being energy efficient means producing the same amount of goods and services with a minor waste of energy. In brief, it means a better exploitation of energy due to the improvement of processes, structures, equipment and efficient technologies providing the same performances at lower cost. Concerning energy supply, we should replace old inefficient thermoelectric plants with more advanced technologies. In doing so, we would globally save 2,800 TWh (9 times the Italian consumption) thus saving 2,2 billion of t/year of CO2 (nearly 9% of total emissions) and avoiding 600 MTEP/year.

In the industrialised countries (including Italy) there are above all 3 sectors accounting for ¾ of the total power consumption:

• Engines/motors (45%)
• Lighting (15%)
• Electrical household appliances (15%)

Energy efficient interventions

An Energy Manager deals with four key factors of the structure: case, plants, equipment and processes. He is in charge of saving energy, reducing costs, making the company more efficient. Here are some projects carried out in industrial plants. They are simple and immediate.

Replacement of the traditional lighting system with LED technology

The first project deals with the replacement of the lighting system (about 1,300 lighting appliances for a total of 90 kW rate output) in an industrial plant. For this energy consumption proof a 10-hour period has been considered. The complete substitution of the old lighting with LED lights and ceiling lamps at 4,000° K has led to a saving of 50%. The business plan here attached (kindly supplied by PVB) describes a 5-year break even but a positive cash flow right from the first year. The replacement of the lighting equipment was made by Esco, which was paid with a share of the money saved (€ 146,000,000 for installation costs plus maintenance expenses).

Replacement of single glazed doors and windows with double glazed doors and windows

In the offices of a re-known Group, they have worked out the energy requirement for heating and cooling and then calculated the time constant related to the casing. The existing doors and windows have been replaced with double-glazed doors and windows thus reducing the loss of heat. As a consequence, the time constant has increased and the time needed to start the plant has been reduced. This substitution means saving for about €60,000 yearly. It will take approximately 10 years to break even. A further study has been carried out on the supply records. In fact, the figures prove that in wintertime there is far more dispersion than in summertime, thus revealing an asymmetric performance of the casing.

Installation of Inverter on recirculation pumps

The heating plump of the building (a warehouse of 20,000 sq. m) has a plant including 23 recirculation pumps and supplying a rated power of 179 kW. The installation of an inverter in a control-command system of an electric motor implies:

• Electric energy saving
• Maximization of resources and processes
• Full integration in management and supervision plants
• Extension of the plant average life
• Reduction in maintenance costs
• Improvement of the system performance

The addition of an inverter on the pumps has helped reduce the inrush current with an economic saving by 40%.

Energy efficiency and continuous improvement

As shown above, here is summarized the possible energy scenario given by three different energy efficient projects. They show how to save energy with reasonable costs by introducing innovative solutions and simple devices in plants or buildings. To conclude, you can save money, reach break even and benefit from continuous upgrading.