Renewable Resources

Are you new to the world of renewable energy? Do you have questions you want to ask but worry about sounding silly? We get it. We were all there once.

In this beginner’s guide, we are going to answer some frequently asked questions about renewable energy and the energy transition. You’ll find out what renewable energy is, get a quick introduction to the different technologies, and learn about the pros and cons of renewable energy sources. And all without having to ask someone face-to-face which, let’s be honest, has rather fallen out of fashion this year.

Let’s get started!

Renewable Energy Definition:

Renewable energy, which is often referred to as ‘green energy’ or ‘green power’, is energy that comes from natural sources that do not run out. These include the sun, the wind and water flow. All of these can be converted into electricity.

Renewables are a cleaner and safer alternative to non-renewable energy sources, such as fossil fuels – including coal, gas and oil – that can only be used once and release harmful pollution into the atmosphere.

Why is renewable energy important?

Renewable energy is important because it enables us to cut carbon emissions that cause climate change and global warming, which is one of the biggest challenges for our planet. Renewables can help us slow and, eventually, reverse the climate crisis.

What are the advantages of renewable energy?

Renewables emit far less carbon dioxide (CO2) emissions than fossil fuels, which is good for our planet. These sources are replenishable, which means they will not run out and could provide an unlimited supply of energy, and economically competitive.

They are also highly flexible. Wind and solar power can be used worldwide, and they are now being paired with big batteries to help them save electricity for later. This will help wind and solar to grow even more. This means that renewable energy is often more accessible and less affected by geopolitical disputes.

Advantages of renewable energy

  • Lower carbon emissions
  • Replenishable sources
  • Economically competitive
  • Can be used globally
  • Helps tackle climate crisis

 

Are renewables cheaper than fossil fuels?

In many parts of the world it’s cheaper to build renewables for electricity generation than to continue running fossil fuel plants. Renewables are also becoming more cost competitive, as wind turbines get larger and solar panels get more efficient. This will help them to convert more power from the wind and sun into electricity.

For example, in 2019, the cost of large solar farms fell 13% and wind fell 9%, based on figures from the International Renewable Energy Agency. The key measurement for calculating the cost of energy sources is the ‘levelized cost of energy’, which is obtained by dividing the lifetime costs of an asset by its energy production.

 

Types of renewable energy sources

Hydropower

Installed capacity: 1,130GW (all capacity figures from IRENA)

How does hydropower work?

Hydropower, or hydroelectric power, is electricity produced from the flow of water. Water flows through a pipe or penstock, and pushes blades in a turbine that spin a generator that produces electricity.

This is an option where water naturally flows at a constant rate, such as rivers, or where a system can be created with dams and reservoirs.

What are the pros and cons of hydropower?

Hydropower is a longstanding technology that can be produced wherever there is flowing water.

However, developers are restricted into where they can deploy hydro as it will only work effectively in an area with a particular topography. It can also be disrupted in case of prolonged shortages in the water supply, as we’ve seen in Brazil. Also, building dams can mean high start-up costs.

 

Pros Cons
–       Established industry –       Can cost a lot up front
–       Consistent production –       Needs specific topography
–       Long-duration storage –       Suffers in drought conditions

 

Is pumped storage a form of hydropower?

Yes. Pumped storage is a system where water is pumped from one reservoir to a higher reservoir nearby. When energy is needed, the water is allowed to flow back down to the lower reservoir, turning a turbine on the way, which creates electricity.

 

Wind energy

Installed capacity: 622GW (594GW onshore / 28GW offshore)

How does wind energy work?

The wind acts on the aerodynamic blades of a wind turbine to make it turn, which turns a generator that produces electricity. This electricity is sent to a transformer that converts it to the correct voltage (or strength) for the local electricity network.

What are the pros and cons of wind energy?

Wind is constantly replenishing, which makes it an abundant source of electricity, and continually evolving turbines mean it can be widely used on land and at sea.

This evolution includes bigger turbines that can harness more of strong winds you find at sea; turbines that can go on sites with slower winds; and modular machines that can be broken into smaller bits so they can be safely installed in remote areas. Wind turbines might all look the same, but there is a great deal of variety.

One big challenge is fluctuating wind speeds, which can affect the ability of wind farm owners to make money. Although companies are increasingly able to manage that with advanced weather forecasting and energy storage. Wind farms can also be controversial with local communities, and this can lead to political resistance, despite the lack of evidence that wind turbines cause health problems.

 

Pros Cons
–       Widespread global support –       Intermittent production
–       Works on land and at sea –       Can face local opposition
–       Ever-evolving technology

 

What is the difference between onshore wind and offshore wind?

The obvious answer is onshore wind is built on land and offshore wind is out to sea!

Beyond that, onshore turbines are smaller, while the latest offshore turbine models can be as tall as skyscrapers. This means offshore wind be better for countries that want to build a lot of renewables and want to minimise objections from landowners.

Offshore wind farms can also now be built in deeper waters on floating foundations.

 

Solar energy

Installed capacity: 578GW globally

How does solar energy work?

Solar energy relies on solar panels that can turn energy from the sun into electricity. They do this by letting protons, or particles of light, knock electrons free from atoms in the solar panel. These atoms create a flow of electricity that can be dispersed into the grid. Clearly, there’s a lot more chemistry happening than we can cover in here!

What are the pros and cons of solar energy?

The sun is an unlimited resource – until it runs out of hydrogen in five billion years’ time, that is! – and is highly predictable. It can also be deployed across most of the world, including on rooftops, and causes less waste than non-renewable sources.

Solar energy faces the same challenge as wind in that it’s intermittent: the sun can’t power solar panels at night, although energy storage can help to ensure electricity is used when it is most needed.

In addition, the global solar market is reliant on Chinese manufacturing, which can cause problems for developers if there are trade wars that disrupt their supplies.

Pros Cons
–       Unlimited energy source –       Intermittent production
–       Highly predictable –       Narrow manufacturing base
–       Works well with storage

 

What is the difference between solar PV and concentrated solar?

Concentrated solar systems use mirrors to focus solar production on a specific point, which is used to heat a liquid that drives an electric generator. This is more complex than solar photovoltaic panels, which create electricity from the sun’s light, not heat. However, concentrated solar has been successfully used in some sunny countries.

Biomass or bioenergy

Installed capacity: 134GW (87GW solid biofuels / 19GW biogas / 15GW municipal waste / 3.2GW liquid biogas)

How does biomass work?

Biomass refers to natural waste materials that have energy from the sun stored in them, such as dead plants. This energy is stored during photosynthesis and, when burned, these energy-rich materials make heat that can turn water into steam. This steam turns a turbine that creates electricity. This is also called ‘bioenergy’.

What are the pros and cons of biomass?

Biomass is considered a renewable energy source because the trees or other plants that are needed to create it can be grown more quickly that non-renewable sources, which can take hundreds of millions of years to replenish. It is also less intermittent than wind and solar, and it can help reduce toxic waste from landfill sites.

However, when burnt, biomass releases carbon dioxide and, if overused, can lead to deforestation or drought because of the land and water needed in its production.

Pros Cons
–       Low levels of intermittency –       Releases carbon dioxide
–       Wide range of applications –       Drought and forest impacts
–       Established industry

What are the different types of biomass?

There are four main types of biomass material:

  • Agricultural products, including wood, bark, sawdust and dead plants
  • Biodiesel, which is a fuel that is usually made from soybean oil
  • Landfill and biogas, where decaying natural waste can be turned into fuel
  • Solid waste, where burning rubbish is turning into useable electricity

Tidal energy

Installed capacity: 531MW

How does tidal energy work?

Tidal power uses the motion of ocean waves or tidal flows to turn turbines that create electricity. It is different to hydro power, which relies on water flowing from a high to a low area, and tidal energy is a far newer technology.

What are the pros and cons of tidal energy?

While tidal energy is intermittent like wind and solar, the movement of the tide is also predictable. This makes it a reliable option. However, the industry is also far smaller than other renewables, so needs political support to take it to commercial maturity.

Pros Cons
–       Predictable tide movements –       Intermittent production
–       Potentially huge market –       Not commercially mature
–       Helped by hydro track record

Are these two sources renewable too?

Finally, we will look at two sources that are both sometimes considered as sources of renewable energy, but both of which raise problems: natural gas and nuclear.

Is natural gas renewable?

Well, that depends on where the natural gas comes from.

If natural gas is produced using methane from animals or landfill materials then it is renewable, as it is replenishable and a by-product of other industrial processes. But some natural gas is derived from finite fossil fuels, which wouldn’t be renewable.

Is nuclear energy renewable?

Nuclear is controversial. It can be considered as a renewable energy source due to the low carbon emissions it produces. Moreover, our planet has large quantities of uranium, which is not expected to run out for a few billion years.

However, uranium particles also produce waste that cannot be recycled, which leads to high decommissioning costs, and nuclear power plants are expensive to build too.

Conclusion

Now we’ve answered all your questions.

You know everything you ever wanted, right?

Honestly, we doubt it.Pexapark was founded in 2017 and many of our team have worked in renewable energy much longer. But the renewable energy industry is growing fast, and we have new questions every day. So don’t sweat it!

That’s why we plan to post more articles like this in the coming months. We want to teach you about the sector we love and show you how it can help change the world.

Or, at very least, make that piece of homework just a little less tricky.

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