Renewable pros and cons

So, about these pros and cons?

Yes. As we said before, to decide what energy sources we should use in the future, we need to know the advantages and disadvantages of each. That way we can decide what would be best - and remember, that is likely to include a mix of energy sources, not just one.

Hydroelectric Power, Hydro or HEP

HEP works by using water stored behind a dam to turn turbines and generate electricity.

A diagram of a HEP plant

Source: By Tomia (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC-BY-2.5 (http://creativecommons.org/licenses/by/2.5)], via Wikimedia Commons

HEP is currently the most used renewable source of electricity, producing just over 15.3% of the World's electricity in 2011.

Source: Jonathan Vizcarra, Quantum Day

 Advantages

HEP is clean (no burning fossil fuels), cheap (once the dam is constructed), reliable (electricity can be produced day and night, all year) and it is a technology we are familiar with. The first HEP plant was built in 1895.

Disadvantages

The major disadvantages of HEP are:
1) The social and environmental impacts cause by flooding large areas of land behind a dam.
2) The need for suitable sites.

Wind Power

Wind turbines work by using the wind to turn turbines to generate electricity.

A diagram of a wind turbine

Source: By Tennessee Valley Authority (tva.com) [Public domain], via Wikimedia Commons

In the UK, onshore wind power (i.e. wind farms build on the land, not out to sea) is one of the cheapest sources of renewable energy. Offshore wind farms are becoming more common, as they have less impact on the landscape, but they are harder to build and so are a more expensive option. However, offshore wind may be the best option in areas where there is not a lot of space for large onshore wind farms.

An offshore windfarm in Sweden

Source: By © 2011 by Tomasz Sienicki [user: tsca, mail: tomasz.sienicki at gmail.com] (Photograph by Tomasz Sienicki (Own work)) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons

 Advantages

Like HEP, wind power is clean (no burning fossil fuels) and once the wind turbines are built, there are no fuel costs as wind is free!

Disadvantages

The major disadvantages of wind power are:
1) The impact of turbines on the landscape (visual and noise pollution) mean people may not want them located nearby.
2) Turbines only generate energy when the wind is blowing - and this is not always when the energy is needed.
3) To generate the amount of energy produced by a power station takes a lot of space (12 power stations = 30,00 wind turbines according to the UK government).

Solar Power

Solar power is produced using  PV (photovoltaic) cells. These cells are able to convert the sun's light into electricity.

Solar panels can be used on a small scale (for example on the roofs of individual buildings), or on a large scale, in 'solar farms'. In 2013, Abu Dhabi opened the largest ever 'concentrated' solar power plant, which uses mirrors to increase the amount of sun's energy that gets to the PV cells and so the amount of electricity produced.

An example of concentrated solar power, in Spain

Source: By afloresm (SOLUCAR PS10) [CC-BY-2.0 (http://creativecommons.org/licenses/by/2.0)], via Wikimedia Commons

 Advantages

Solar power, like HEP and wind power, does not produce greenhouse gases and has no fuel cost. It can be used at a variety of scales, from individual homes to large scale farms and as the technology develops, PV cells are becoming cheaper, making solar power more affordable.

Disadvantages

The major disadvantages of solar are:

1) There are obviously places that solar power is better suited to. So far, the biggest solar farms have been built in places with hot, sunny climates (like Abu Dhabi and Spain), that get a lot of sun throughout the year. As the map below shows, some places receive much more solar energy than others.

Map to show solar energy across Europe

SolarGIS © 2011 GeoModel Solar s.r.o. [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

2) Solar panels take up a lot of space - if used in farms, they are best suited to areas that can't be used for other things and where they won't harm natural habitats. There are suggestions to use the tops of roofs to harvest solar energy, as these are often 'wasted' space.

Other Renewable Sources

There are a number of other renewable sources, including wave power, tidal power, biomass and geothermal energy - you can find out about the advantages and disadvantages of these here and here.

So, are renewables the future?

Renewables definitely have to be part of the future - apart from anything else, it seem silly not to use these 'free' sources of energy when people are so worried about energy costs. However, the technologies for many of them will have to be improved if they are to produce enough energy cheaply enough. Also, where they are used needs to be thought about carefully so that they do not have unacceptable social and environmental effects. Whether this can be done quickly enough for us to reduce our reliance on fossil fuels is debatable.

A renewable future?

So we really don't want fossil fuels?

Not in the long run. Although some countries are focussing on using gas (instead of coal or oil) because it is less polluting, the fact is, it still contributes to carbon dioxide in the atmosphere, and most government organisations, including the EU and the UN and are agreed that this needs to be reduced.

Also, fossil fuels are finite; at some point they will run out, and unless we cut out energy use dramatically, we will need something else to replace them with.

So what about renewables?

That's a good question. There are many people and organisations who think that the future 'energy gap' can be filled with renewable energy sources. They argue investment and research will enable us to 'scale-up' technologies to replace coal, oil and gas.

Are they right?

There has definitely been an increase in the use of renewables for producing electricity across the globe.
Some countries in the world manage to produce over 80% of their electricity from renewable sources. However, all of these are countries blessed with geography that allows them to make massive use of hydroelectric power (HEP).

A HEP dam in Brazil

Source: By Andre Borges Lopes (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

A HEP dam in Norway

Source: Rehro [CC-BY-SA-3.0-de (http://creativecommons.org/licenses/by-sa/3.0/de/deed.en)], via Wikimedia Commons

Other countries have managed to dramatically increase their use of renewables. Portugal is one such example. By focussing on developing wind, wave and solar energy, as well as hydroelectric power, it now generates 45-50% of its energy using renewable sources.

Solar power in Portugal

Source: Ceinturion at the English language Wikipedia [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], from Wikimedia Commons

Great! What's stopping us?

Well, there are issues. Not everyone is blessed with sunshine, constant winds and waves, steep river valleys and so on. Some places will find it harder than others to make use of renewables.

There are difficulties with storing energy from renewable sources that only generate power some of the time - like wind and solar.

Wind turbines don't generate energy when the wind doesn't blow

Source: Shooter's Bottom wind turbine at dusk (Sharon Loxton) / CC BY-SA 2.0

Also, many renewables are regarded as expensive, and people aren't keen on paying more for their energy.

In addition, each form of renewable energy has its own advantages and disadvantages. These have to be considered before we decide what to use, which is our next job.