Climate explained: how much of the world’s energy comes from fossil fuels and could we replace it all with renewables?

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Robert McLachlan, Massey University

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Climate explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz

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How are fossil fuels formed, why do they release carbon dioxide and how much of the world’s energy do they provide? And what are the renewable energy sources that could replace fossil fuels?

Fossil fuels were formed over millions of years from the remains of plants and animals trapped in sediments and then transformed by heat and pressure.

Most coal was formed in the Carboniferous Period (360–300 million years ago), an age of amphibians and vast swampy forests. Fossilisation of trees moved enormous amounts of carbon from the air to underground, leading to a decline in atmospheric carbon dioxide (CO₂) levels — enough to bring the Earth close to a completely frozen state.

This change in the climate, combined with the evolution of fungi that could digest dead wood and release its carbon back into the air, brought the coal-forming period to an end.

Oil and natural gas (methane, CH₄) were formed similarly, not from trees but from ocean plankton, and over a longer period. New Zealand’s Maui oil field is relatively young, dating from the Eocene, some 50 million years ago.

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Burning buried sunshine

When fossil fuels are burnt, their carbon reacts with oxygen to form carbon dioxide. The energy originally provided by the Sun, stored in chemical bonds for millions of years, is released and the carbon returns to the air. A simple example is the burning of natural gas: one molecule of methane and two of oxygen combine to produce carbon dioxide and water.

CH₄ + 2 O₂ → CO₂ + 2 H₂O

Burning a kilogram of natural gas releases 15kWh of energy in the form of infrared radiation (radiant heat). This is a sizeable amount.

To stop continuously worsening climate change, we need to stop burning fossil fuels for energy. That’s a tall order, because fossil fuels provide 84% of all the energy used by human civilisation. (New Zealand is less reliant on fossil fuels, at 65%.)

Wind energy is one of the renewable sources with the capacity to scale up.
Shutterstock/YIUCHEUNG

There are many possible sources of renewable or low-carbon energy: nuclear, hydropower, wind, solar, geothermal, biomass (burning plants for energy) and biofuel (making liquid or gaseous fuels out of plants). A handful of tidal power stations are in operation, and experiments are under way with wave and ocean current generation.

But, among these, the only two with the capacity to scale up to the staggering amount of energy we use are wind and solar. Despite impressive growth (doubling in less than five years), wind provides only 2.2% of all energy, and solar 1.1%.

The renewables transition

One saving grace, which suggests a complete transformation to renewable energy may be possible, is that a lot of the energy from fossil fuels is wasted.

First, extraction, refining and transport of fossil fuels accounts for 12% of all energy use. Second, fossil fuels are often burnt in very inefficient ways, for example in internal combustion engines in cars. A world based on renewable energy would need half as much energy in the first place.

The potential solar and wind resource is enormous, and costs have fallen rapidly. Some have argued we could transition to fully renewable energy, including transmission lines and energy storage as well as fully synthetic liquid fuels, by 2050.

One scenario sees New Zealand building 20GW of solar and 9GW of wind power. That’s not unreasonable — Australia has built that much in five years. We should hurry. Renewable power plants take time to build and industries take time to scale up.

Other factors to consider

Switching to renewable energy solves the problems of fuel and climate change, but not those of escalating resource use. Building a whole new energy system takes a lot of material, some of it rare and difficult to extract. Unlike burnt fuel, metal can be recycled, but that won’t help while building a new system for the first time.

Research concluded that although some metals are scarce (particularly cobalt, cadmium, nickel, gold and silver), “a fully renewable energy system is unlikely to deplete metal reserves and resources up to 2050”. There are also opportunities to substitute more common materials, at some loss of efficiency.

Building a new system will require energy and resources.
Shutterstock/Jacques Tarnero

But many metals are highly localised. Half the world’s cobalt reserves are in the Democratic Republic of Congo, half the lithium is in Chile, and 70% of rare earths, used in wind turbines and electric motors, are in China.

Wasteful consumption is another issue. New technologies (robots, drones, internet) and economic growth lead to increased use of energy and resources. Rich people use a disproportionate amount of energy and model excessive consumption and waste others aspire to, including the emerging rich in developing countries.

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Renewable energy can save the natural world – but if we’re not careful, it will also hurt it

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Research analysing household-level emissions across European countries found the top 1% of the population with the highest carbon footprints produced 55 tonnes of CO₂-equivalent emissions each, compared to a European median of 10 tonnes.

Scientists have warned about consumption by the affluent and there is vigorous debate about how to reduce it while preserving a stable society.

One way of turning these questions around is to start from the bottom and ask: what is the minimum energy required for basic human needs?

One study considered “decent living” to include comfortable housing, enough food and water, 10,000km of travel a year, education, healthcare and telecommunications for everyone on Earth — clearly not something we have managed to achieve so far. It found this would need about 4,000kWh of energy per person per year, less than a tenth of what New Zealanders currently use, and an amount easily supplied by renewable energy.

All that carbon under the ground was energy ripe for the picking. We picked it. But now it is time to stop.

Robert McLachlan, Professor in Applied Mathematics, Massey University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Albanese says we can’t replace steelmaking coal. But we already have green alternatives

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Dominique Hes, University of Melbourne

Despite a wealth of evidence to the contrary, some still propagate the myth that the world will need Australian coal for decades to come. Last weekend Opposition Leader Anthony Albanese joined in, saying thermal and metallurgical coal mining and exports would continue after 2050, even with a net zero emissions target.

Metallurgical coal (or “coking coal”) is mined to produce the carbon used in steelmaking, while thermal coal is used to make steam that generates electricity.

Albanese argues there’s no replacement for metallurgical coal, but this is not the case. The assertion stems from a fundamental misunderstanding of modern steelmaking, and places Australian manufacturers at risk of missing out on massive opportunities in the global shift to a low-carbon economy.

Just as thermal coal can be replaced with clean energy from renewables, we can use low-emissions steel manufacturing to phase out metallurgical coal.

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The problem with steel

Steel is the second-most polluting industrial material in the world after cement, causing 7-9% of global emissions.

Australia manufactures a relatively small amount of steel – 5.3 million tonnes, or 0.3% of world output. Yet, we’re one of the biggest exporters of raw materials for steel production.

There is potential to not only strengthen Australia’s steel manufacturing industry, but also to grow it using the ore (rock containing metals like iron) we currently export and our extensive renewable energy sources.

Doing so would work to our manufacturing strengths, history, abundant resources, and would cater to the future low-carbon market that will still require steel.

There are a few ways we can do this.

Recovering waste

Seventy-two per cent of the world’s virgin steel (steel made from ore, not from recycled material) is created from a high emissions manufacturing process – via the integrated steel-making route. This involves a blast furnace and a basic oxygen furnace, using coal, coke, iron ore and gas.

We can replace the coal and coke with rubber tyres that would otherwise end up in landfill, as shown by University of NSW’s Professor Veena Sahajwalla, who dubbed this process “green steel”.

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Right now we can also boost the recovery of steel from landfills in greater percentages. According to a 2018 national waste report, Australia generated an estimated 67 million tonnes of waste in 2016-17.

Steel makes up 2.5% of this. That’s more than 1.5 million tonnes, enough to build 150,000 buses.

‘Direct reduction’ from renewable hydrogen

But the best way to reduce emissions in steel manufacturing is to shift to “direct reduction”. This process produces more than 60 million tonnes of primary steel each year.

And almost 50 plants around Australia already make steel this way. It results in 40% lower greenhouse gas emissions, while supporting a viable and thriving manufacturing industry, which uses our own raw materials rather than exporting them.

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Enough ambition (and hydrogen) could get Australia to 200% renewable energy

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Here’s how it works. Direct reduction removes the oxygen in ore, which produces metallic iron. The chemical reaction that drives this process uses carbon monoxide and hydrogen, sourced from greenhouse gases – reformed natural gas, syngas or coal.

But there’s no reason these fossil fuels can’t be entirely replaced with renewable hydrogen in the near future.

We’ve seen this from two leading direct-reduction technologies, called Midrex and Energiron. Both use fossil fuels, but also with a high proportion of hydrogen. In fact, Energiron facilities can already use up to 70% hydrogen, and they’ve also trialled 100% hydrogen.

The source of this hydrogen is critical, it can be made from fossil fuels, or it can be made using renewable energy.

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Read more:
For hydrogen to be truly ‘clean’ it must be made with renewables, not coal

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At least five companies in Europe are also working on producing low emissions steel. What’s more, three companies (SSAB, LKAB and Vattenfall) are collaborating to progress the technology, creating the “world’s first fossil-free steel-making technology, with virtually no carbon footprint” – called the “HYBRIT system”.

In fact, SSAB recently announced they’re bringing their plans forward to will produce fossil-free steel by 2026.

A new Aussie industry

The key message is this: it is possible to create low-emissions steel, without metallurgical coal. And it is already happening.

With the support of industry and government, non-metallurgical, low-emissions steel could provide an opportunity to create jobs, develop a decarbonised industry and extend the steel market’s contribution to Australia’s economy.

Not to mention what products we can produce from the steel – adding value in many more ways than just exporting ore – and taking advantage of an increasing consumer demand for low carbon products. This is especially relevant for communities transitioning away from fossil fuels.

There’s not much stopping low-emissions steel from forming a core new Australian industry. Australia must address the costs involved in transitioning the infrastructure, to upgrade plants and processes.

But it needs to start with working from facts – and effective government support and vision.

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How hydrogen power can help us cut emissions, boost exports, and even drive further between refills

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Dominique Hes, Senior Lecturer in Sustainable Architecture, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Storage can replace gas in our electricity networks and boost renewables

Dylan McConnell, University of Melbourne

Energy storage could replace peak gas in our electricity network. That’s the finding of a study that my colleagues and I recently published in the Journal of Applied Energy.

Energy storage is often considered the holy grail of the electricity sector. Tesla’s Powerwall home battery system, for instance, allows households to store energy from solar panels, to be used when the sun isn’t shining. It is seen as a vital piece of the puzzle in a future with more renewable energy.

Storage is great for households, but could also be as important in the wider electricity network. Here’s how it could work.

Volatile prices

Generators or power stations sell their electricity on a wholesale market (in eastern Australia this is the National Electricity Market or NEM). From there it is passed onto households and businesses by retailers at retail prices. The wholesale price is a significant factor in the cost of electricity (other factors include poles and wires).

The wholesale price varies throughout the day – sometimes quite considerably, as you can see in the chart below from Queensland. In times of peak demand, prices can skyrocket to 300-400 times the average price.

Half-hourly wholesale electricity prices in Queensland, at the beginning of this year. The average price for the full 2014-2015 financial year was about $50/MWh.
(Author provided, data from AEMO)

This volatility is largely a result of physics: generators have to match demand instantaneously, because electrical energy can’t directly be stored.

People don’t use electricity equally throughout the day. Usually electricity use is concentrated at the end of the day, or on the very hottest day of summer when people fire up their air conditioners.

Electricity networks are typically set up to meet the maximum possible peak demand. They meet this demand with flexible generators such as open cycle gas turbines (which are quick to fire up and shut down, unlike generators such as coal-fired power stations). Such “peak” gas generators are typically used less than 5% of the time.

Load duration curve for the National Electricity Market in the 2008-09 financial year. Curve illustrates the percentage of time that the system is at or above a particular demand level. A large amount of capacity is required for small time periods throughout the year.
Author provided, data from AEMO

These rapid variations in energy demand, along with outages of generators or transmission lines and generator bidding behaviour on the market, can result in highly volatile prices. This is where storage can play a role.

Energy can be stored as chemical energy (in the case of batteries), or in other ways such as gravitational potential energy (in the case of pumped hydro), to be used later to generate electricity when convenient.

These electricity storage technologies can also provide peak capacity. In our paper, we found that this was the main value of energy storage. In fact, peak capacity potential may turn out to offer greater value than other options for meeting peak demand.

Surprisingly, we found this value wasn’t affected by energy losses involved in storage (not all energy is recovered when released from storage).

Powering up with storage and renewables

Due to its high flexibility, gas is often considered to be an ideal partner for renewable energy, because it can pick up the slack when the sun isn’t shining or the wind isn’t blowing.

But as the share of renewable energy continues to expand, large-scale electricity storage offers a promising alternative to gas.

In fact, a study by the Australian Energy Market Operator suggested that significant energy storage was crucial to a 100% renewable energy system, in order to minimise costs while maintaining reliability and security standards.

Our research found that storage actually has a competitive advantage over gas when it comes to meeting peak demand. While both can provide peak capacity, storage can also gain extra revenue by taking advantage of smaller price differences that occur on a more frequent (such as daily) basis. When taking this into account, storage may already be cheaper than gas in meeting peak demand. New reports from the US estimate batteries could replace gas in 3-5 years.

Relative costs of providing capacity from an open cycle gas turbine (OCGT) and pumped hydro electric storage (PHES). The right most bar shows the cost of capacity when the revenue from daily arbitrage is taken into account.
(Author provided)

Australia’s electricity system is currently oversupplied with capacity to generate electricity – by around 37%. As such, there appears to be no need for new capacity for the foreseeable future.

However, there may be demand for new storage capacity if older generators are withdrawn from the electricity network. Alternatively, the outlook for storage may improve as renewable energy generation is increased to meet mandated targets.

Increasing penetration of variable renewable energy will increase revenues for storage. In times of high generation output there will be more opportunities for storage owners to shop around for lower prices. This fluctuation between prices is already happening in South Australia.

In this way, storage and renewables may prove mutually beneficial.

Dylan McConnell, Research Fellow, Melbourne Energy Institute, University of Melbourne

This article was originally published on The Conversation. Read the original article.

Check In: Day 2 of Holiday

I have had a most interesting couple of days on the road and in the bush. Currently I’m in a motel room at Woolgoolga, near Coffs Harbour on the mid-north coast of New South Wales, Australia. ‘Hardly the wild,’ I hear you say, and you’re quite right – it isn’t. The weather was beginning to change I noticed on the final leg of my day’s itinerary, so I decided to hide out in a motel room for the night – good decision, it’s pouring outside.

I won’t give all away – I’ll leave the main description of the holiday to the website – but just some of the ‘downlights’ of the first couple of days for this post.

I didn’t arrive at Cathedral Rock National Park until just on dark, but did get the tent up prior to darkness arriving – when it did, it was dark! The campfire took an eternity to get going as all of the timber was damp and by the time I got it started it was time for bed – all-be-it an early night (7.30pm). I had decided to not spend the money on replacing all of the gear I needed to replace for camping, following the loss of a lot of gear over the years due to storage, etc. I hadn’t done much in the way of bushwalking or camping for years due to injuries sustained in my car crash and a bad ankle injury, so I left it all a bit late. I figured that for this holiday I’d make do and replace the gear with quality gear before the next trip. In short, I’ll get by – but it would have been nice to have some good gear just the same. It was a very cold night let me tell you – and long.

When I reached the heights of my first walk today, standing on top of Cathedral Rock National Park, my digital camera decided to die on me. I knew there was something wrong with it during the ascent as it was really chugging away taking pictures. I did get a couple of reasonable panoramic shots on the top of Cathedral Rock before it died, so that was good. I took stills with the video camera I was using, so it wasn’t a complete loss. When I completed the Woolpack Rocks walk I made the trip to Coffs Harbour to seek a replacement and got one for a reasonable price. It’s just another compact and so I will also buy a digital SLR prior to my next trip I hope. My previous SLR was basically destroyed when the camera cap came off during a multiple day bushwalk and all manner of stuff got into it. It wasn’t digital so I didn’t bother repairing it.

So tomorrow – off to Dorrigo National Park I hope and several lengthy walks I haven’t done before. Hopefully the rain will clear.