There’s a lot of talk about renewable energy, but there are lots of questions about it. Here’s some facts about types of renewable energy, why it’s good, whether it’s practical, and how a renewable energy system would work.
What is renewable energy?
Energy in our world is used primarily in three ways: power, heating and transport. In the past, the majority of this energy has been produced by burning coal, oil, gas and wood. This form of energy is a finite resource (except for wood) that will soon run out.
Renewable energy, on the other hand, doesn’t run out because it is naturally available and not consumed – from the sun, wind, tides and other ocean energy, hydro-power, etc.
- Solar: Solar photovoltaic panels convert sunlight into electricity in a silicon solar cell. Solar thermal panels store the sun’s heat directly for us in space heating or hot water systems. Solar panels can be deployed in small arrays on rooftops or in large arrays in solar farms.
- Wind: The power of the wind can be harnessed by wind turbines to create electricity. It is estimated that wind power could supply 70% of Australia’s future requirements.
- Hydro: Water falling over a waterfall or flowing out of a dam has energy that can be converted to electricity via turbines. Pumped hydro, where water is pumped to an elevated storage when supply exceeds demand and then released to generate electricity when demand is high, is a valuable and necessary storage technology. It is currently used in several locations in Australia, particularly in Tasmania and the Snowy Scheme, and more are expected to be constructed.
- Ocean: The restless energy of the oceans can be harnessed in a number of ways. The movement of tides, waves and ocean currents can be converted to electricity by turbines. The difference in temperature between ocean surface and floor can be converted to energy. At present tidal energy seems to be most viable for Australia.
- Geothermal: The heat from molten rock below the earth’s surface can be utilised to provide heat or generate electricity via steam turbines. At present it isn’t considered to be economic in Australia, but this may change.
- Bio and waste: Several different chemical processes can produce heat, electricity, biogas or liquid fuels from organic materials (biomass), found in wastewater and in municipal, agricultural, forestry and industrial waste. Globally, bioenergy was the source of half of all renewable energy used in 2017.
- Hydrogen: Passing an electric current through water (electrolysis) can separate it into hydrogen and oxygen gases. The hydrogen can be liquified in the form of ammonia and able to be used as a fuel, just like oil and gas. Except when hydrogen is used as a fuel, it’s waste product is water – it contains no carbon!
- Batteries: Large scale batteries are a necessary part of any renewable energy system to even out fluctuations in supply.
Why is it good?
Renewable electricity generation is now cheaper than coal and gas-fired electricity, and the cost is expected to continue to fall. In Australia (and generally elsewhere), coal-fired power stations are beginning to be closed before their design life because they are no longer economic.
While renewable energy plants may be expensive to build, their operation requires no fuel and is relatively cheap. Their levelised cost of energy (LCOE) – the cost of supplying electricity over their entire life – has become lower than coal, gas or nuclear.
Renewable power generation is generally far less polluting than energy generated by burning fossil fuels, so it’s healthier for the planet and for people.
Burning fossil fuels emits particles in to the atmosphere which are harmful to human health and are estimated to cause at least 1-2 million premature deaths each year worldwide.
Burning fossil fuels also releases greenhouse gases in far greater quantities than other renewable power generation.
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It is more flexible
Fossil fuel power generation is generally via large and costly power stations that require enormous up-front investment with uncertainty about whether that investment will be profitable.
On the other hand, renewable energy generation can be provided by plants that are small and local, even down to rooftop solar power, as well as larger plants. The initial investment can be smaller and much of the energy can be generated close to where it is needed.
It provides energy independence
Australia imports oil and exports coal and gas. This makes our transport systems (which depend on oil) vulnerable if war or the economy make oil less readily available. Other countries are who import our coal and gas are vulnerable in a similar way.
In contrast, renewable energy sources are far less vulnerable because they are far less dependent on imports from overseas.
Can renewable energy supply all our needs?
To be 100% renewable, all our energy needs (power, transport and heating) would have to be provided by electricity or heat generated from renewable resources.
There are disagreements about whether this is practicable. Increasing our use of renewable energy, especially for power generation, is easy, because it has become cheaper. But increasing the amount of renewable sources becomes more costly because they don’t produce a constant supply – solar plants don’t generate power at night and wind farms don’t generate energy on still days. Thus increased energy storage is required.
But experts say close to 100% renewable energy can be practically achieved, with carbon capture from the atmosphere allowing us to achieve net zero emissions. Australia is especially capable of achieving close to 100% renewable energy generation, because:
- We are a large country, so a national electricity grid allows power to be sources from the other side of the continent. It is rare that there won’t be wind or sun somewhere in Australia.
- Pumped storage hydro-power is available. The Snowy Scheme together with other sites are capable of providing more than sufficient capacity for the required pumped hydro if Australia moves to 100% renewable-sourced electricity.
- Large scale batteries can provide short term storage to fill in gaps in power generation.
- Tidal and geothermal power can also provide consistent base-load power, and Australia has a large coastline to generate tidal power.
So close to 100% renewable is feasible for Australia. Other countries may not be as well placed as Australia is.
Renewable energy worldwide
Many countries around the world have moved to renewable energy much more than Australia has. Two figures are important here: the percentage of electricity generation from renewable sources and the percentage of total energy from renewable sources. Typically it is easier to generate electrical power from renewable sources than it is to use renewable sources for transportation.
Costa Rica, Iceland, Norway, Paraguay and Uruguay plus many African countries are close to 100% renewable electricity generation. European countries like Sweden, Germany and UK have ambitious plans to move to renewable electricity. Australia generates just over 20% of its electricity from renewable sources (21% in 2019).
I have found it hard to obtain consistent figures for total renewable energy use, but it is clear it is much lower.
- According to OECD a bunch of African and Central and South American countries have more than half their total energy from renewable sources,.
- In the European Union, about 20% of total energy comes from renewable sources, with renewables making up 38% of electricity (compared to 37% from fossil fuels, with nuclear making up most of the rest), 20% of heating and cooling and almost 10% of transport energy. Only Iceland, Norway and Sweden are above 50%.
- Australia’s total energy from renewables is just 7%, just over half the world average.
So it is clear that it is possible (even for less wealthy countries) to move to a high level of renewable energy. And despite our many advantages of space, wind, sun and coastline, Australia is well behind most of the world.
What will renewable energy look like in Australia?
It all starts with electricity generation.
There are two requirements of an electricity generation system: it must be large and reliable enough to provide the base load demand (the amount of electricity required day in and day out) plus it must be flexible enough to meet sudden changes in demand in peak periods.
Current Australian energy generation
Australia currently has one major electricity grid (the National Electricity Market, NEM) covering all states except WA and NT, and several smaller grids. The NEM’s main source of power is 19 coal-fired power stations which provide the base load (68% of total). Additional (often peak) power comes from gas (8%) and renewables – wind (7.5%), grid solar (3%), small rooftop solar installations (6%) and hydroelectricity (7.1%).
Heating and transport energy is also mostly provided by fossil fuels – gas and electricity for heating and oil for transport.
Future Australian energy generation
In the future, as coal-fired power stations are phased out, having reached the end of their economic life, renewables will be responsible for more and more of the base load. Renewables are excellent for peak demand because they can be switched on and off easily, but they are not always able to supply base load when there is no wind or sunlight. Rooftop solar and smaller local wind and solar sources will supply a significant part of demand (likely more than a third of total capacity), while larger solar and wind farms can conveniently be built in more remote locations. All this will require major modifications to the supply networks.
Because the NEM grid is one of the largest in the world, there will rarely be times when there is no wind or sun across the whole network, but shortfalls will be common. Large battery storage can even out the fluctuations and pumped hydro, tidal and possibly geothermal will fill in the larger gaps. Experts are confident that close to 100% renewable electricity is practicable, cheaper than any alternatives such as gas or nuclear, safer and cleaner.
Electricity, solar thermal and geothermal can replace most gas for heating and cooling, but the bigger challenge is transport. Electric car technology is advancing rapidly, and if the government sponsored the establishment of a network of charging stations, electric vehicles will be suitable for most uses. This will require creating new capacity in the electricity grid.
Some remote locations will be difficult to provide for electric vehicles, but hydrogen power will eventually be viable for air travel and large road transport, and perhaps even for cars one day. So some fossil fuel usage will continue for a time at least. To achieve net zero carbon emissions will thus require some carbon capture to offset this transport usage.
The bottom line
Renewable energy is the way of the future. It will be cleaner, healthier, cheaper and practical.
If the government phased out the billions of dollars of subsidies to the fossil fuel industry and invested that money in the renewable energy network, Australia could become a renewable energy and technology innovator and exporter.
The Australian Energy Market Operator says there are “no fundamental limits to 100% renewables”, and that the current standards of the system’s security and reliability would be maintained.
- Renewable Energy. Australian Renewable Energy Agency.
- Setting the Record Straight About Renewable Energy. Susan Tierney & Lori Bird, World Resources Institute, May 2020.
- Fact sheet: The National Electricity Market. Australian Energy Market Operator, July 2020.
- National Electricity Market. Chapter 2 in State of the Energy Market, Australian Energy Regulator, 2018.
- What would Australia look like powered by 100% renewable energy? Nicky Ison, Guardian, January 2019.
- 100% renewable electricity in Australia. Andrew Blakers, Bin Lu, Matthew Stocks, ANU, May 2017.
- Renewable energy makes business sense. Hughes Fact Check, March 2021.
Photo: Wind turbines by CSIRO.