Let’s energize

A Coruña!

Let’s energize A Coruña! During this last month, we have been

working on a project in which we have learnt a lot about the different types of energy and how to save it.

The first activity was audiovisual. We watched a video about energy. The monitor explained to us the importance of a reasonable use of energy, and we shared our point of view about it.

Everybody became aware of how important it is to save energy.

Audiovisual

Energy Energy is the power

derived from the utilization of physical or chemical resources, essentially to provide light and heat or to work machines.

Types of energy

There are two sources of energy: Renewable energy . Nonrenewable energy.

Nonrenewable Sources of Energy Most of the energy we use comes from fossil

fuels, such as coal, natural gas and petroleum. Uranium is another nonrenewable source, but it is not a fossil fuel. Uranium is converted to a fuel and used in nuclear power plants. Once these natural resources are used up, they are gone forever.

The process of gathering these fuels can be harmful to the biomes from which they come. Fossil fuels are put through a process called combustion in order to produce energy. Combustion releases pollution, such as carbon monoxide and sulfur dioxide, which may contribute to acid rain and global warming.

Renewable Sources of Energy

Renewable sources of energy can be used over and over again. Renewable resources include solar energy, wind, geothermal energy, biomass and hydropower. They generate much less pollution, both in gathering and production, than nonrenewable sources.

Renewable Sources of Energy

Solar energy comes from the sun. Some people use solar panels on their homes to convert sunlight into electricity.

Wind turbines, which look like giant windmills, generate electricity.

Geothermal energy comes from the Earth's crust. Engineers extract steam or very hot water from the Earth's crust and use the steam to generate electricity.

Biomass includes natural products such as wood, manure and corn. These materials are burned and used for heat.

Dams and rivers generate hydropower. When water flows through a dam it activates a turbine, which runs an electric generator.

Let’s energize A Coruña!

Next day, we visited Bens’ cogeneration plant, as well as Nostian’s waste treatment plant.

We learnt a lot about how they work and we had a great time sharing this experience together.

Bens’ Cogeneration Plant Cogeneration could be defined as improving the

performance of installations by joint production and use of electricity.

In contrast to the conventional process, starting with fuel (e.g. crude oil or natural gas), in which only electricity is obtained, in cogeneration both the electricity obtained and the resulting vapour are considered useful. Vapour is used in industrial processes and for heating public centres such as the swimming pools of San Amaro and San Diego.

La Coruña has four cogeneration plants to save energy and make the most of the biogas produced by city waste at the Nostián Waste Treatment Plant and in the old Bens landfill.

The beginnings The Bens landfill, opened in the late

Seventies to receive the waste produced by 400,000 inhabitants of the nearby municipalities, was accumulating against the valley walls, in a mixture of litter and soil which was not properly compacted. A fire contributed to destabilising the landfill, which eventually collapsed.

The beginnings In September 1996, 200000

m3 of garbage collected in the landfill rolled down the mountainside into the sea, burying everything in its path (vehicles, houses, boats) and killing a man.

The beginnings Yet, this event had an enormous impact

on the public’s and the authorities’ sense of civic responsibility, as it considerably increased the awareness of the importance of finding a sustainable solution to the waste management.

A Coruña developed a waste treatment model, which envisaged the construction of the Nostián plant to produce compost and recycling waste.

Recovery of Bens Landfill In order to recover this public space, the following

different steps were taken: Preparing the land: Once over a million cubic metres had

been removed, the first step was to stop it from moving. Gigantic steps were integrated into the hillside - in the future they will form part of a leisure area. Some areas were even carefully cleaned by hand. This was the case with the rocks, home to a wide range of flora and fauna such as lichen, moss, lizards, etc.

Sealing the landfill: Different layers of different materials guarantee correct waste draining and waterproofing from rain. On top there is a layer of grass to cover the old landfill. The distribution fits in perfectly with the area and allows better plant growth.

Recovery of Bens Landfill Runoff and gas treatment: Even though the

waste is not visible, it is still there. This should not be forgotten. A large amount of tubes have been installed under the landfill to capture all the runoff, which might be contaminated after contact with waste. This liquid is pumped into a pre-treatment plant. Waste decomposition also produces biogas, which needs to get out. Vertical wells up to 7 metres deep capture this gas, which is taken through a 20km long network of pipes and burnt at the chimneys. Soon it will be taken to a cogeneration plant to produce electricity. In a few years' time, waste will stop producing gas.

Recovery of Bens Landfill Replanting: Once the

landfill was sealed, the whole area was covered with different kinds of grass. The surface area with waste underneath has been sealed off to the public for fifteen years, when the waste will stop producing gas and then the area will be incorporated into the rest of the park.

Recovery of Bens Landfill

Nostián’s Waste Treatment Plant

It is composed of three modules: The first is a plant where

organic and inorganic waste are separated. In turn, the latter is separated into paper and cardboard, plastics and glass, which are then delivered to the companies in charge of their recycling.

Nostián’s Waste Treatment Plant

A second plant treats the organic waste and puts it into a bio digester, along with water and microorganisms, where it undergoes anaerobic fermentation for 1 month at 35°C. In the decomposition process, the organic waste produces biogas which is used as a source of energy.

Afterwards, the organic matter is dewatered and transferred to the plant for aerobic composting, where it remains for 40 days.

The resulting compost can be sold in the market, mainly to the agricultural sector.

Workshop After this experience, we had to show all that we had

learnt by playing a game with the monitor. It was a lot of fun!!

Final project To finish this project, we created ppt

presentations, explaining the different types of energy, the pros and cons of each one of them, how the waste treatment plants we visited work, etc.

We also had to think of different ways to save energy.