Greenhouse gas emissions – Sustainable Gas Institute Blog

What are the best options for road freight transport?

7 April 2021

Pedro Gerber Machado, a visiting researcher from the University of São Paulo, Brazil, summarises his recent review paper examining the life cycle emissions for road freight transport. The review was carried out in collaboration with the Institute of Energy and Environment at the University of São Paulo, Brazil.

Author: Pedro Gerber Machado

The transport sector is responsible for around 30% of the world’s energy consumption and 16% of greenhouse gases (GHG) emissions. To achieve an energy transition to guarantee net-zero emissions, reducing emissions from road transport is fundamental. Diesel is still the most common fuel used for heavy road transport and freight. While worldwide there is a move towards electric vehicles, their environmental benefit in reducing emissions depends on the area’s electricity sources. Our review paper examines the total environmental life cycle emissions of different fuel options and technologies for road freight transport (trucks) in 45 studies.

Source of electricity

The source of electricity can make a big difference to greenhouse gas emissions. We found that with greenhouse gas emissions, higher values (3,148–3,664 g/km) are found in places where coal has a significant share in electricity generation. Lower emissions are found where renewables have higher percentages in electricity generation (496 g/km). In China, emissions can reach 5,479 g/km since electricity generation “is mostly from coal.”

Compressed Natural Gas (CNG)

For Compressed Natural Gas (CNG) technology, greenhouse gas emissions vary due to differing efficiency and assumptions about methane leakage during natural gas transportation. But future projections are optimistic due to the potential for improvements in controlling methane emissions (514 g/km in 2050).

Biodiesel

In the analysis, biodiesel had a higher energy consumption and higher emissions profile in the production phase equal to diesel, which is the main reason for its low environmental performance.

Hydrogen

The greenhouse gas emissions intensity from hydrogen varies as it is depends on its method of production such as coal gasification, steam methane reforming (SMR), and hydrolysis. The use of carbon capture and storage (CCS) and liquid or gaseous use also influences its final emission profile.

Fuels vs. diesel

On average, the review showed that biogas, fuel-cell hydrogen, and Liquefied Natural Gas (LNG) have lower emissions in their life cycle than diesel, with a chance of a 57% reduction in emissions for biodiesel, 77% for fuel-cell hydrogen, and 100% chance for biogas. Interestingly, even though biodiesel is a renewable source of fuel that receives significant attention due to its capacity to reduce greenhouse gas emissions, in our review, it had a higher average emission than diesel.

Battery electric, hydrogen fuel cells and biogas

We found that if a clean electricity matrix is available, with high renewable energy shares, battery electric vehicles provide the best option. Hydrogen fuel-cells, when hydrogen comes from renewable sources, are also comparable to battery electric vehicles. Biogas can serve as a feedstock for hydrogen production in substituting natural gas in steam methane reform or liquefied for use in Liquid Natural Gas (LNG) trucks.

Further research into biogas emissions, fuel consumption, and its economics is essential. Since biogas production is possible from several sources, it could be suitable for different countries, such as Brazil.

Analysing air pollutants

There is a lack of studies exploring the life cycle of these options when it comes to air pollutants. Even though pollutant emissions in the use phase (for internal combustion options) have received more attention from the scientific community, emissions for the whole life cycle should also be studied. Even so, uncertainties related to the Tank-to-Wheel evaluation can increase the inaccurate values from this side of the analysis and the error propagation, directly impacting the policymakers. For PM2.5, hybrid and LNG options have greater changes in reducing the emissions. Fuel-cell, LNG, CNG, and hybrid trucks have higher chances of reducing nitrogen oxide (NOx) emissions. In contrast, sulphur oxide (SOx) emissions came out inconclusive due to a lack of studies.

But what about the economics…

CNG, LNG, and hybrid trucks were the best options from an economic perspective. CNG has lower life cycle costs and fuel costs in most analyses, with values ranging from 50% lower life cycle costs than diesel to a 2% reduction, to 16% average increase. CNG is the most economical fuel for large fleets that conduct urban operations and can support private infrastructure.

LNG could have a payback time of 2.5 years or lower, considering the price differential mostly in long-haul operations due to its lower fuel costs. However, economic viability could be achieved due to the higher cost of LNG vehicles and maintenance and the limited range of LNG trucks relative to diesel. The studies also showed that the fuel efficiency in LNG trucks could dictate its economic viability. Relative efficiencies of less than 80% reduce the chances of lower costs by 50%.

Finally, hybrid trucks show a total life cycle cost from 10% lower to practically no difference. Although the incremental cost of hybrid trucks is expected to become close to zero in the future, additional investments of more than $35,000 in hybrid technology hinder its viability, especially with low diesel fuel costs.

In the developing world…

The question arises then if the best options regarding GHG and local pollutant emissions will ever be a possibility for developing regions. Even though authors point out that electric trucks could cause an increase in emissions in several places in the world and that it is still necessary to evaluate peak power demand to understand the operational aspects of transport electrification, electric trucks in countries with a high share of renewables have the most radical reductions in GHG. However, being the most expensive options, there is a slight chance that governments in poorer countries or even the private sector will be willing to pay the price, based solely on environmental reasons.

The way to go in these countries has been to continue to depend on diesel. Most recently, the discussion on natural gas use in the transport sector has gained some momentum. Cheaper than other alternative options, natural gas might be an option due to its lower PM emissions, even though other pollutants, or GHG emissions, are higher.

Exploring ways to decarbonise heat in Chilean cities

Zara Qadir

1 March 2019

Chile is committing to decarbonising its electricity sector with a target of 60% renewable power by 2035, but there are still some challenges with decarbonising the heat sector. Chileans still rely heavily on natural gas to heat their homes. Jorge Salgado Contreras from Chile, visited the Sustainable Gas Institute for two months, funded by the Chilean National Commission for Science and Technology, and tasked with investigating ways of developing heat decarbonisation pathways for cities in Chile. We interviewed Jorge about his research.

What is your background?

I am an industrial engineer and now Head of the Electrical and Electronics Department at Inacap in Punta Arenas University, Chile. I have combined experience in the energy sector, working in academic, private and public sectors. In the private sector, I have worked for both the national gas retailer (Intergas Inc) on both business development and the technical side, as well as in an energy start-up. I also worked for the Ministry of Energy of Chile, on renewable energy and energy efficiency projects, where I was in charge of cogeneration initiatives and lead the long-term energy plans for two cities in Patagonia.

How did you find out about the Sustainable Gas Institute, and what first sparked your interest in working here?

I found the Sustainable Gas Institute website, and it was actually the name that first caught my attention. I really liked the aims of the Institute as it is clear we cannot move to 100% renewables straight away, and a transition is necessary. I also thought the White Paper Series is really trying to address some unresolved issues. Even though the reports are written by academics, they are very influential from a policy context.

The energy mix in Chile (Source: Ministry of Energy, Chile).

Your project is to understand how to decarbonise heat for Chile. Can you tell us why it’s so important an issue?

Chile is actually very cold, especially the southern end which is where I am from; it can go below -10 °C. While Chile has ambitious climate targets to increase renewables to 70% by 2050, these targets have only been set for the electricity sector and there are little targets, plans or research taking place to reduce the emissions intensity of the heat sector.

We currently use so many energy to heat our homes in Chile. Fortunately, Chile does have a good renewables portfolio (22% renewables), increasingly with solar and wind. However, in my region (Magallanes and chilean Antarctica, Chile), we still use natural gas to heat our homes, as you do in the UK. We do have access to our own natural gas and biomass but in other regions, for example in Southern Chile, natural gas is imported from overseas. The natural gas subsidy for residential and commercial use in the Magallanes region is around 100 million US$/year and represents about 70% of the Chilean Ministry of Energy National Budget.

What is the project about and who have you been working with?

I have been trying to understand whether we can work with low-carbon options such as hydrogen to decarbonise the existing gas grid infrastructure. In Chile, there is not much research taking place to understand the role of hydrogen in heat decarbonisation.

I have also been looking at the use of electrification and technologies, such as heat pumps. The recent report by the UK Committee on Climate Change into this was very useful as a case study. The idea is to adapt for the Chilean context, and we could move forward towards a low carbon economy by replacing natural gas with hydrogen.

At the Institute, I have been mainly working with both Dr. Paul Balcombe (an expert in the supply chain for hydrogen) and Dr. Francisca Jalil Vega (who is highly knowledgeable about various heat decarbonisation options).

And finally, have you enjoyed your time at Imperial College? What do you plan to do next?

Map of Magallanes and Chilean Antarctica Region (Source: Wikimedia Commons)

I am hoping to publish a paper with Francisca and Paul, and I will continue working on this during the coming months. I might be speaking in a congress and will present my work to the Ministry of Energy in Chile.

It has been great working at Imperial College because it such a world-class international university and I really like the interdisciplinary environment. There are so many people doing relevant research here!

Read Jorge’s biography on the Sustainable Gas Institute website.

Header Photo: Picture of Torres del Paine in Patagonia in Chile (Source: Pixabay).

VIDEO: My research in a nutshell – Sandro on reducing industry emissions

Zara Qadir

19 March 2018

How to reduce emissions from industry?

By the time you finish your masters, you’ll know your thesis inside out. We challenged one of our researchers at the Sustainable Gas Institute to explain their research in a short one minute video as part of the ‘Research in a Nutshell Series’.

Sandro Luh is a visiting Masters student from the ETH Zurich. He is using the MUSE energy systems model to examine the potential of different strategies for reducing CO2 emissions in the industrial sector. This includes measures such as fuel switching, electrification and Carbon Capture & Storage.

The industrial sector is a key sector to decarbonise as it accounts for 24% of the total global CO2 emissions (2014).

If you want to find out more about Sandro’s work, read our short interview with him.

Investigating the state of low-carbon transport policies at COP22

Zara Qadir

22 November 2016

Last week, Arnaud Koehl, a PhD researcher at the Department of Primary Care and Public Health at Imperial College, attended the United Nations Conference of the Parties COP22 climate conference in Marrakech. Arnaud is investigating the kind of sustainable transport policies that could co-benefit health and the economy while addressing climate change.

The importance of transport in combating climate change

The transport sector represents about 14% of worldwide greenhouse gases emissions (Intergovernmental Panel on Climate Change IPCC, 2010). More worryingly, the International Energy Agency (IEA) projects a huge growth in private motorised modes of transport; according to these estimates, there will be around 2 billion cars on the roads by 2040! It is therefore paramount that we find low-carbon pathways that will meet the increasing demand for mobility.

So how will these transport emissions (addressed by the Paris Agreement) be enforced by 2020? The way the Agreement is framed relies on the good will of each nation or signatory: countries put forward policies to reduce greenhouse gases emissions for each economic sector (e.g. industry, agriculture, housing) themselves. The legal name for these voluntary targets is “Intended Nationally Determined Contribution” (INDC). This architecture provides the flexibility needed to address climate policies according to the local context. This strategy proved to be quite successful as three out of four of all countries mention transport in their INDCs.

bikes-small — Cycle-sharing demonstration scheme in front of COP22

Lessons from COP22: Chinese engagement, policy trends and international cooperation

In the spirit of the Paris Agreement, COP22 proposes a “strong vision, light touch”. I was particularly interested in what this meant for China. The National Development and Reform Commission (NDRC), an important governmental body, just released a report titled “China’s policies and actions for addressing climate change – 2016” .

This report mentions that fuel efficiency improved by 15.9% (2005) for private cars and ships and by 13.5% (2016) for the civil aviation sector. A director at the NDRC, whom I interviewed, stressed that this was the result of an emphasis on “green, circular, low-carbon” policies imposed on the private sector within the 12^th (2011 -2015) and 13^th (2016-2020) five-year plans of the Chinese government. He was also clear on the fact that these policies are being tested and implemented through thousands of projects around China.

In terms of transport modes, I found a clear consensus on acknowledging the benefits of implementing Bus Rapid Transit systems across populated urban areas. These are dedicated lanes, typically in the center of the road. The increased use of trains and trams were also leading to a consensus between representatives from differing nations, such as Ethiopia and the United States. Smarter forms of using private motorised modes, such as carpooling, car-sharing, on-demand taxis were also seen as potential ways of reducing emissions.

Beyond its final results, COP22 was also the opportunity to seal partnerships to spread good practices internationally. Initiatives from official actors and civil society are soaring in an attempt to implement green policies on time. A good example is Mobilise Your City, gathering 100 cities around the world supporting local governments in developing countries to plan and foster sustainable low-carbon urban mobility. A core belief that Mobilise Your City is promoting among its members is that improving mobility is only relevant if there is a net well-being effect.

How research at the Sustainable Gas Institute can help

At the start of the year, I was working on the transport module of a new energy systems model developed by researchers at Sustainable Gas Institute (SGI), Imperial College London. The model is called MUSE (Modular Universal energy system Simulation Environment). The aim is that industry will be able to use the model for technology and R&D roadmapping, while it will help international governments make future plans for climate change mitigation.

Uses of the MUSE Model

MUSE could help answer key COP22 issues. Many participants at COP-22 stressed the lack of research on freight transport, despite the fact that it represents half of overall transport emissions. By taking into account freight-related transportation, MUSE enables us how to assess how policy-makers could avoid unwanted developments, such as a spread of high polluting cars, by looking at the incidence of the price of new technologies based on factors such as economic growth.

Another major opportunity would be to look at the improvement in fuel efficiency of current technologies, such as diesel, petrol and hybrid. Indeed, the share of electric vehicles in the world’s fleet will soar, but fossil fuel powered vehicles will remain an important part of the equation until 2050.

Finally, the MUSE model allows to test such interventions at the national level, which is a relevant scale as powerful policy-makers are often found in capitals. Sanjay Sath, from The Energy and Resources Institute, and Jose Viegas, from the International Transportation Forum expressed the necessity of adopting a dual approach, by implementing national policies at the local level. In that perspective, many highlighted the critical need to get more indicators measuring the progress of environmental policies on the ground to ensure of actual improvement of well-being. An example of such indicators is the proximity of public transport to social housing.

MUSE could make the most of the currently available data in order to give an insight on the future place of transport in urban dynamics, and thus help calculating these indicators further.

You can find out more about MUSE here.

BLOG: Building a cleaner natural gas supply chain

Zara Qadir

29 October 2015

The last few days in October saw the Gastech conference and exhibition carried out at the massive Singapore Expo. It was a large affair, with all the major gas companies discussing the most pressing issues for them, particularly emerging gas markets and the prospective rise of Liquefied Natural Gas (LNG). Helge Lund, the CEO of BG group, gave a keynote speech to kick off the conference. He gave his view on the challenges of incorporating gas in a lower carbon world: both a carbon price and a commitment from the industry to reduce methane and carbon dioxide emissions are vital.

It is indeed a challenge to incorporate a fossil fuel into a lower carbon world. Natural gas is likely to play a crucial role on two fronts: reducing the dependency on the more carbon-intensive coal; and providing variable and peak electricity supply as a compliment to intermittent renewables. If we are going to carry on using gas for these services in the short and medium term, the environmental impacts must be minimised.

Our recent white paper at Sustainable Gas Institute published in September, assessed what we know about both methane and carbon dioxide emissions from the natural gas supply chain. The study found emissions to be highly variable, with some significant ‘hotspots’.

In particular, very high methane emissions were found for liquids unloading processes, gas-driven pneumatic devices and compressors. For all of these sources, emissions were very variable and there are technologies and techniques that can minimise or even eliminate emissions. For example, gas-driven pneumatics could be replaced with instrument air drivers, compressors must be inspected regularly and dry-seals are much lower emitters than wet-seals for centrifugal compressors. The economic feasibility of these changes is likely to be variable but in many cases positive: i.e. a lower product loss more than pays for the increased capital or operating cost.

Another finding of the white paper on supply chain emissions was the appearance of ‘super emitters’ all across the supply chain.

Recent studies have found evidence of a small number of facilities or equipment that emit far more than the average, which significant skews the emissions distribution. These super emitters are likely to be due to the faulty or incorrect operation of equipment or ineffective inspection and maintenance procedures. Detecting the super emitters is the key challenge here, but once we do so, average emissions from the supply chain would be reduced significantly.

In summary, no technological innovation is needed to reduce supply chain emissions significantly, only commitment to action from the gas industry. It is very promising to hear words of such commitment from world leading gas producers at Gastech and now is the time to act on this.

If you are interested in finding out more, please download the report, or a short summary note or watch our short video.

To register for our monthly newsletter, email SGI@imperial.ac.uk or follow us on twitter @SGI_london.

BLOG: Tackling methane’s contribution to climate change

Zara Qadir

13 October 2015

A blog by Dr Paul Balcombe from the IPIECA-OGCI Workshop.

On Monday 12^th October, I presented at a workshop in Paris which was focussed on understanding methane emissions from the natural gas supply chain. It was a conference organised by IPIECA and OGCI, who are both voluntary initiatives set up by major oil and gas producers to share knowledge on emissions reductions.

It was great to get a chance to present the work of the Sustainable Gas Institute on methane and carbon dioxide emissions from the supply chain to all these new faces: about 30 new perspectives from industry, as well as some from government, academia and NGOs.

The aim of the conference was really to pool together all of our knowledge on what we currently know about methane emissions from the natural gas industry. The idea is that we can identify the most important gaps in our knowledge that we need to fill and to discuss how we can start to do this.

Key headlines

One of the highlights of the conference was a talk by Prof Myles Allen from the Environmental Change Institute at the University of Oxford. He delved into detail about the complicated issue of how potent methane is compared to carbon dioxide in terms of climate change. Methane is much more potent in the short term but doesn’t last as long in the atmosphere, so has a much lower lasting effect than CO₂. Prof Allen says that, because of this, we need to make sure that we focus on both methane and CO₂: if we don’t reduce CO₂, we will never stabilise our greenhouse gas emissions; but if we don’t reduce methane, we will have a much larger global temperature when we do reach the peak.

Another eye-opener was from a talk by Steve Hamburg, who heads up the work done by the Environmental Defense Fund on direct methane measurement all across the US. It was great to hear him talk so passionately about the massive task of emissions measurement and reduction. One of the take home messages Steve made was that reducing methane emissions is extremely important because this reduces the speed that we are warming the climate (whereas reducing CO₂ reduces the overall temperature).

The key challenges that we summarised from the end of the first day were:

We need to increase methane emissions data collection. We have seen a big rise in data collection in the US which is great, but we need this to continue to other regions and more downstream emissions measurement.
It is clear that emissions are highly variable and it is vital that data represents the high distribution of emissions.
It is also vital that data is validated independently. Much work is going on by the industry to measure and in future publish emissions data, but the data must be validated so that transparency is maximised.
There is real potential to reduce emissions further and the technology is there. The key is to do this in as low cost as possible and to ensure that appropriate mechanisms are in place to detect super emitters quickly.

If you are interested in finding out more about the subject, read our recent paper (or a short summary) on the challenge of methane and CO₂ emissions in the natural gas supply chain.