Welcome everyone to this episode in the series in which we will explore the issue of Renewable Energy and continue this also into the next episode. We will start with a general introduction and then explain some of the most common related terms. I am your host Victor and I am delighted to have Colm with me to help explore this topic.
Hi Everybody. Technically, energy is broadly defined as the capability of doing work – so moving something around, heating and cooling a building, making a product all takes energy. It can take many different forms but the most common form used over the past two hundred years has been fossil fuels such as oil, natural gas and coal which have been formed over billions of years. Burning these fuels creates what are called greenhouse gases such as carbon dioxide and methane. These gases cause the greenhouse effect which is where the surface of the planet heats up because radiation cannot escape due to these gases. However, energy can be sourced from renewable resources which are naturally replenished on a human timescale and include sun, wind and wave energy. Such resources can be used for electricity generation, heating or cooling and for transportation.
Renewable Energy is an energy source that renews itself without effort. Fossil fuels, once consumed, are gone forever, whilst the sun energy we harvest today has no effect on the sun energy we can harvest tomorrow. Renewable energy resources – sometimes referred as simply renewables – are naturally replenishable, but they are flow-limited – that is not always available – such as solar is not available at night. Renewables are virtually inexhaustible in supply but limited in the amount of energy that is available at any given time. For this reason they require a change in the infrastructure of the industry and marketplace which is a slow process. Despite this renewables contributed approximately twenty percent of energy consumption globally in 2016.
We should make a distinction also between some similar terms used – For instance Alternative or Clean energy are often used as other terms for renewable energy. However, these are not precise in meaning and may also be used to refer to non-renewable sources that have fewer emissions than fossil fuels. For example, they can also refer to nuclear energy, natural gas or even what is called clean coal – which is treated to reduce the emissions when burnt.
When people use the term Green energy they are referring to the environmental impact of the energy. For example, hydro electricity is a renewable source but many people would argue that it is not green because of the environmental impact of constructing reservoirs and dams and interrupting the natural river environments.
The term Sustainable Energy refers to energy from renewable resources and also includes the idea of energy efficiency and efforts to reduce the amount of energy wasted.
We will now explain some terms associated with renewable electricity.
Renewable electricity is generated without the use of fossil fuels. Electricity is what is called a public good – that is a good or service that will not be delivered by the free market alone. So often national governments are very involved in structuring the supply of electricity across a country. The large corporations that own and operate the generating plants and the transmission of electricity are referred to as utilities and these are heavily regulated.
The word grid means the interconnected electricity system in an area including everything from the generation plant to the supply in a house. Most electricity is distributed to houses and businesses from very large generating plants using a network of cables called the transmission grid to distribute power over a large area. This is called a centralised generation system. This system was designed for a time of very cheap fossil fuel supplies and no real awareness of the environmental impacts.
In a more sustainable market we would need to move to what is called distributed or decentralised generation as the associated emissions are much lower. This is quite common in some European countries. The most common form is using smaller generating plants and capturing the excess heat produced and providing it to local houses and buildings in what is called a Combined Heat and Power system. There are also stand alone heating systems which are called District Heating system. Such systems can provide energy or heat to a small group of houses or even to a city region.
In some regions and countries it is becoming common for the utilities to make it possible for consumers to also supply electricity back into the distribution system. For example, a house that has solar panels on the roof and is generating more power than required can export the excess onto the grid for supply to other users. Customers that both consume and produce electricity are called Prosumers. The householder is paid a rate per unit by the utility for this energy called a Feed-in Tarriff. This is often different to the unit cost of electricity to the consumer.
Another system called net metering is when the price paid by the utility company for supply into the system is the same as the price paid by the consumer for electricity consumed.
The term off-grid refers to a house or community that is not connected to any government or private utility’s power lines. The generation of heat or power using renewable sources by individuals, businesses or communities for their own use is called micro-generation. A small network of electricity users with a local source of supply, able to function independently is referred to as a Microgrid.
The term Smart Grid is the title given to an electricity grid enabled with computer technology to automate the monitoring and control of electrical generation, distribution and use. An associated term is Smart meter which is an advanced utility meter that has the ability to identify the production and consumption in more detail than a conventional meter. This information is communicated back to the utility companies for monitoring and billing purposes.
The production and distribution of our energy and electricity is a major source of pollution through the emissions from fossil fuels. A lot of combined efforts are needed to change this dramatically as we work towards a more sustainable future.
That concludes this episode of the series which we hope you have found informative and helpful. In the next episode we will look at the different renewable sources available. My thanks to Colm for his help and to you for listening. We do hope you can join us on future episodes of the series.