Why battery-powered vehicles stack up better than hydrogen



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A battery electric vehicle in The University of Queensland’s vehicle fleet.
CC BY-ND

Jake Whitehead, The University of Queensland; Robin Smit, The University of Queensland, and Simon Washington, The University of Queensland

Low energy efficiency is already a major problem for petrol and diesel vehicles. Typically, only 20% of the overall well-to-wheel energy is actually used to power these vehicles. The other 80% is lost through oil extraction, refinement, transport, evaporation, and engine heat. This low energy efficiency is the primary reason why fossil fuel vehicles are emissions-intensive, and relatively expensive to run.

With this in mind, we set out to understand the energy efficiency of electric and hydrogen vehicles as part of a recent paper published in the Air Quality and Climate Change Journal.

Electric vehicles stack up best

Based on a wide scan of studies globally, we found that battery electric vehicles have significantly lower energy losses compared to other vehicle technologies. Interestingly, however, the well-to-wheel losses of hydrogen fuel cell vehicles were found to be almost as high as fossil fuel vehicles.

Average well-to-wheel energy losses from different vehicle drivetrain technologies, showing typical values and ranges. Note: these figures account for production, transport and propulsion, but do not capture manufacturing energy requirements, which are currently marginally higher for electric and hydrogen fuel cell vehicles compared to fossil fuel vehicles.

At first, this significant efficiency difference may seem surprising, given the recent attention on using hydrogen for transport.




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While most hydrogen today (and for the foreseeable future) is produced from fossil fuels, a zero-emission pathway is possible if renewable energy is used to:

Herein lies one of the significant challenges in harnessing hydrogen for transport: there are many more steps in the energy life cycle process, compared with the simpler, direct use of electricity in battery electric vehicles.

Each step in the process incurs an energy penalty, and therefore an efficiency loss. The sum of these losses ultimately explains why hydrogen fuel cell vehicles, on average, require three to four times more energy than battery electric vehicles, per kilometre travelled.

Electricity grid impacts

The future significance of low energy efficiency is made clearer upon examination of the potential electricity grid impacts. If Australia’s existing 14 million light vehicles were electric, they would need about 37 terawatt-hours (TWh) of electricity per year — a 15% increase in national electricity generation (roughly equivalent to Australia’s existing annual renewable generation).

But if this same fleet was converted to run on hydrogen, it would need more than four times the electricity: roughly 157 TWh a year. This would entail a 63% increase in national electricity generation.

A recent Infrastructure Victoria report reached a similar conclusion. It calculated that a full transition to hydrogen in 2046 – for both light and heavy vehicles – would require 64 TWh of electricity, the equivalent of a 147% increase in Victoria’s annual electricity consumption. Battery electric vehicles, meanwhile, would require roughly one third the amount (22 TWh).




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Some may argue that energy efficiency will no longer be important in the future given some forecasts suggest Australia could reach 100% renewable energy as soon as the 2030s. While the current political climate suggests this will be challenging, even as the transition occurs, there will be competing demands for renewable energy between sectors, stressing the continuing importance of energy efficiency.




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It should also be recognised that higher energy requirements translate to higher energy prices. Even if hydrogen reached price parity with petrol or diesel in the future, electric vehicles would remain 70-90% cheaper to run, because of their higher energy efficiency. This would save the average Australian household more than A$2,000 per year.

Pragmatic plan for the future

Despite the clear energy efficiency advantages of electric vehicles over hydrogen vehicles, the truth is there is no silver bullet. Both technologies face differing challenges in terms of infrastructure, consumer acceptance, grid impacts, technology maturity and reliability, and driving range (the volume needed for sufficient hydrogen compared with the battery energy density for electric vehicles).

Battery electric vehicles are not yet a suitable replacement for every vehicle on our roads. But based on the technology available today, it is clear that a significant proportion of the current fleet could transition to be battery electric, including many cars, buses, and short-haul trucks.

Such a transition represents a sensible, robust and cost-efficient approach for delivering the significant transport emission reductions required within the short time frames outlined by the Intergovernmental Panel on Climate Change’s recent report on restraining global warming to 1.5℃, while also reducing transport costs.

Together with other energy-efficient technologies, such as the direct export of renewable electricity overseas, battery electric vehicles will ensure that the renewable energy we generate over the coming decades is used to reduce the greatest amount of emissions, as quickly as possible.




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Meanwhile, research should continue into energy efficient options for long-distance trucks, shipping and aircraft, as well as the broader role for both hydrogen and electrification in reducing emissions across other sectors of the economy.

With the Federal Senate Select Committee on Electric Vehicles set to deliver its final report on December 4, let’s hope the continuing importance of energy efficiency in transport has not been forgotten.The Conversation

Jake Whitehead, Research Fellow, The University of Queensland; Robin Smit, Adjunct professor, The University of Queensland, and Simon Washington, Professor and Head of School of Civil Engineering, The University of Queensland

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

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



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Could this be the way to fill up in future?
CSIRO, Author provided

Sam Bruce, CSIRO

Hydrogen could become a significant part of Australia’s energy landscape within the coming decade, competing with both natural gas and batteries, according to a new CSIRO roadmap for the industry.

Hydrogen gas is a versatile energy carrier with a wide range of potential uses. However, hydrogen is not freely available in the atmosphere as a gas. It therefore requires an energy input and a series of technologies to produce, store and then use it.

Why would we bother? Because hydrogen has several advantages over other energy carriers, such as batteries. It is a single product that can service multiple markets and, if produced using low- or zero-emissions energy sources, it can help us significantly cut greenhouse emissions.

Potential uses for hydrogen.
CSIRO, Author provided

Compared with batteries, hydrogen can release more energy per unit of mass. This means that in contrast to electric battery-powered cars, it can allow passenger vehicles to cover longer distances without refuelling. Refuelling is quicker too, and is likely to stay that way.

The benefits are potentially even greater for heavy vehicles such as buses and trucks which already carry heavy payloads, and where lengthy battery recharge times can affect business models.




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Hydrogen can also play an important role in energy storage, which will be increasingly necessary both in remote operations such as mine sites, and as part of the electricity grid to help smooth out the contribution of renewables such as wind and solar. This could work by using the excess renewable energy (when generation is high and/or demand is low) to drive hydrogen production via electrolysis of water. The hydrogen can then be stored as compressed gas and put into a fuel cell to generate electricity when needed.

Australia is heavily reliant on imported liquid fuels and does not currently have enough liquid fuel held in reserve. Moving towards hydrogen fuel could potentially alleviate this problem. Hydrogen can also be used to produce industrial chemicals such as ammonia and methanol, and is an important ingredient in petroleum refining.

Further, as hydrogen burns without greenhouse emissions, it is one of the few viable green alternatives to natural gas for generating heat.

Our roadmap predicts that the global market for hydrogen will grow in the coming decades. Among the prospective buyers of Australian hydrogen would be Japan, which is comparatively constrained in its ability to generate energy locally. Australia’s extensive natural resources, namely solar, wind, fossil fuels and available land lend favourably to the establishment of hydrogen export supply chains.

Why embrace hydrogen now?

Given its widespread use and benefit, interest in the “hydrogen economy” has peaked and troughed for the past few decades. Why might it be different this time around? While the main motivation is hydrogen’s ability to deliver low-carbon energy, there are a couple of other factors that distinguish today’s situation from previous years.

Our analysis shows that the hydrogen value chain is now underpinned by a series of mature technologies that are technically ready but not yet commercially viable. This means that the narrative around hydrogen has now shifted from one of technology development to “market activation”.

The solar panel industry provides a recent precedent for this kind of burgeoning energy industry. Large-scale solar farms are now generating attractive returns on investment, without any assistance from government. One of the main factors that enabled solar power to reach this tipping point was the increase in production economies of scale, particularly in China. Notably, China has recently emerged as a proponent for hydrogen, earmarking its use in both transport and distributed electricity generation.

But whereas solar power could feed into a market with ready-made infrastructure (the electricity grid), the case is less straightforward for hydrogen. The technologies to help produce and distribute hydrogen will need to develop in concert with the applications themselves.

A roadmap for hydrogen

In light of this, the primary objective of CSIRO’s National Hydrogen Roadmap is to provide a blueprint for the development of a hydrogen industry in Australia. With several activities already underway, it is designed to help industry, government and researchers decide where exactly to focus their attention and investment.

Our first step was to calculate the price points at which hydrogen can compete commercially with other technologies. We then worked backwards along the value chain to understand the key areas of investment needed for hydrogen to achieve competitiveness in each of the identified potential markets. Following this, we modelled the cumulative impact of the investment priorities that would be feasible in or around 2025.


CSIRO, Author provided

What became evident from the report was that the opportunity for clean hydrogen to compete favourably on a cost basis with existing industrial feedstocks and energy carriers in local applications such as transport and remote area power systems is within reach. On the upstream side, some of the most material drivers of reductions in cost include the availability of cheap low emissions electricity, utilisation and size of the asset.




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The development of an export industry, meanwhile, is a potential game-changer for hydrogen and the broader energy sector. While this industry is not expected to scale up until closer to 2030, this will enable the localisation of supply chains, industrialisation and even automation of technology manufacture that will contribute to significant reductions in asset capital costs. It will also enable the development of fossil-fuel-derived hydrogen with carbon capture and storage, and place downward pressure on renewable energy costs dedicated to large scale hydrogen production via electrolysis.

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The Conversation

In light of global trends in industry, energy and transport, development of a hydrogen industry in Australia represents a real opportunity to create new growth areas in our economy. Blessed with unparalleled resources, a skilled workforce and established manufacturing base, Australia is extremely well placed to capitalise on this opportunity. But it won’t eventuate on its own.

Sam Bruce, Manager, CSIRO Futures, CSIRO

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

Explainer: how do we make hydrogen from coal, and is it really a clean fuel?


Jessica Allen, University of Newcastle

Energy giant AGL this week unveiled plans to produce hydrogen power at its Loy Yang A coal station. But how do we transform coal, which is often thought of as simply made of carbon, into hydrogen – a completely different element?

In fact, coal is not just made of carbon. It also contains other elements, one of which is hydrogen. But to get a lot of hydrogen, the coal needs to be “gasified” rather than burned, creating compounds that can then be reacted with water to make hydrogen. This is where the majority of hydrogen comes from in this case – not from the coal itself.




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What is coal made of?

In simple terms, coal is a mixture of two components: carbon-based matter (the decayed remains of prehistoric vegetation) and mineral matter (which comes from the ground from which the coal is dug). The carbon-based matter is composed of five main elements: carbon, hydrogen, oxygen, nitrogen and sulfur.

You can think of coal’s formation process as a progression from biomass (newly dead plant matter) to charcoal (almost pure carbon). Over time, the oxygen and some hydrogen are gradually removed, leaving more and more carbon behind.

Brown coal thus contains slightly more hydrogen than black coal, although the biggest difference between the two is in their carbon and oxygen contents.

https://datawrapper.dwcdn.net/HUgdy/2/

What is gasification?

We can understand gasification by first understanding combustion. Combustion, or burning, is the complete oxidation of a fuel such as coal, a process that produces heat and carbon dioxide. Carbon dioxide itself cannot be further oxidised, and thus is the non-combustible end product of the burning process.

In gasification, however, the coal is not completely oxidised. Instead, the coal is reacted with a compound called a gasification agent. Gasification is endothermic, which means it doesn’t produce heat. Quite the opposite, in fact – it needs heat input to progress. Because the resulting gas is not fully oxidised, that means it can itself be burned as a fuel.

So how do we make hydrogen?

Now we know the key concepts, let’s start again at the start. To produce hydrogen from coal, the process begins with partial oxidation, which means some air is added to the coal, which generates carbon dioxide gas through traditional combustion. Not enough is added, though, to completely burn the coal – only enough to make some heat for the gasification reaction. The partial oxidation also makes its own gasification agent, carbon dioxide.

Carbon dioxide reacts with the rest of the carbon in the coal to form carbon monoxide (this is the endothermic gasification reaction, which needs heat input). No hydrogen yet.

Carbon monoxide in the gas stream is now further reacted with steam, generating hydrogen and carbon dioxide. Now we are making some hydrogen. The hydrogen can then be run through an on-site fuel cell to generate high-efficiency electricity, although the plan at Loy Yang A is to pressurise the hydrogen and ship it off to Japan for their Olympic showcase.

Making hydrogen from coal.
J. Allen

Brown coals are generally preferred for gasification over black coals for several reasons, which makes the brown coal of Victoria’s Latrobe Valley a good prospect for this process.

The main reason is that, because of the high oxygen content of this type of coal, it is less chemically stable and therefore easier to break apart during the gasification reaction. Plus there is a small boost from the hydrogen that is already present in the coal.

Hydrogen produced in this way is not a zero-emission fuel. Carbon dioxide is emitted through the combustion and thermal decomposition reactions, and is also a product of the reaction between carbon monoxide and water to make hydrogen and carbon dioxide.

So why bother making hydrogen?

When hydrogen is used as a fuel, it releases only water as a byproduct. This makes it a zero-emission clean fuel, at least at the point of use.

Producing hydrogen from coal in a large, central facility means pollution control can be put in place. Particulates, and potentially carbon dioxide, can be removed from the gas stream very efficiently.

This is not possible on a small scale, such as hanging off the back of your car. Road transport currently emits dangerous levels of pollutants in our cities every day.




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Gasification processes that use hydrogen fuel cells on site can substantially increase their efficiency compared with traditional coal-fired power. However, depending on the end-use of the hydrogen, and subsequent transport processes, you might be better off in terms of energy output, or efficiency (and therefore carbon emissions), just straight-up burning the coal to make electricity.

But by using gasification of coal to make hydrogen, we can start building much-needed infrastructure and developing consumer markets (that is, hydrogen fuel cell vehicles) for a truly clean future fuel.

The ConversationI predict that hydrogen power will be zero-emission one day. It can be made in a variety of ways through pure water splitting (including electrolysis, or through solar thermochemical and photoelectrochemical technologies, to name a few). It’s not there yet in terms of price or practicality, but it is certainly on its way. Boosting development of the hydrogen economy through production from coal in the meantime is, in my book, not a terrible idea overall.

Jessica Allen, Researcher and Lecturer in Low and Zero Emission Energy, University of Newcastle

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