Losing the Climate War to Methane? The role of methane emissions in the global warming puzzle

Posted on by Highwire Earth

Written by Dr. Arvind Ravikumar

There is much to cheer about the recent climate agreement signed last December at the 21st Conference of Parties (COP 21) in Paris, France to reduce greenhouse gas emissions and limit global temperature rise to below 2° C. Whether countries will implement effective policies to achieve this agreement is a different question. Leading up to the Conference in Paris, countries proposed their intended nationally determined contributions (INDCs). These refer to the various targets and proposed policies pledged by all countries that signed the United Nations Framework Convention on Climate Change on their intended contribution to reduce global warming. The United States, among other things, is banking on the recently finalized Clean Power Plan by the Environmental Protection Agency (EPA) – this policy aims to reduce US greenhouse gas (GHG) emissions from the power sector by 26 to 28% in 2030, partly by replacing high-emitting coal fired power plants with low-emitting natural gas fired plants, and increased renewable generation (primarily wind and solar). Electricity production by natural gas fired plants is therefore expected to increase over the next few decades, acting as a ‘bridge-fuel’ to a carbon-free economy. Even though the US Supreme Court recently halted the implementation of the Clean Power Plan, the EPA anticipates that it will eventually be upheld.

A major component of natural gas is methane. This is a highly potent greenhouse gas whose global warming potential (i.e. ability to increase the Earth’s surface temperature through the greenhouse effect) is 36 times that of carbon dioxide in long-term (100-year impact) and over 80 in the near-term (20-year impact). Although carbon dioxide is a major component of US greenhouse gas emissions (see Fig. 1), it is estimated that methane contributes around 10% of the total emissions. Thus, given its significantly higher global warming potential, methane emissions and leakage can potentially erode the climate benefits of declining coal production.

Figure 1: US greenhouse gas inventory (2013) Data from EPA
Figure 1. US greenhouse gas inventory (2013). Source: EPA

Methane emissions are fairly diversified across natural and man-made sources. Figure 2 shows the sources of methane emissions in the US (2013) as estimated by the EPA through its GHG monitoring program. While 50% of emissions can be attributed to agriculture and waste-disposal activities, we can see that about 30% of methane emissions come from the oil and gas industry. Much of this can be attributed to the recent boom in non-conventional or shale gas production through fracking technology. The combination of low natural gas prices and higher demand from the power sector makes it imperative to reduce methane emissions as much as technologically feasible.

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Figure 2. US methane emission by source (2013) . Source: EPA.

Currently, methane leaks occur at all stages of the natural gas infrastructure – from production and processing, transmission to distribution lines in major cities. While the global warming effects of higher methane concentrations are fairly well understood, there is currently little consensus on the magnitude of emissions from the natural gas infrastructure. For example, a recent study found that the average methane loss in all distribution pipelines around Boston was about 2.7%, significantly higher than the 1.1% reported in inventory estimates to the EPA. Another study that was published in the academic journal, Science, showed that various independent measurements of methane leakage rate across the US infrastructure varied from about 1% to over 6%. Climate benefits of switching from coal to natural gas fired power plants would critically depend on this leakage rate.

[…], detailed measurements from the Barnett shale region in Texas showed that just 2% of the facilities in the region account for 50% of all the methane emissions.

To better estimate methane leakage, the Environmental Defense Fund (EDF), a non-profit organization based in Washington, DC, organized and recently concluded a series of 16 studies to find and measure leaks in the US natural gas supply chain. While some of the results are currently being analyzed, much of the data show that conventional inventory estimates maintained by the EPA have consistently underestimated the leakage from various sources. It was shown that the Barnett shale region in Texas that produces about 7% of the nation’s natural gas, emitted 90% more methane compared to EPA estimates. To complicate matters further, until recently, estimates from atmospheric top-down data measured using satellites and aircrafts significantly exceeded land-based bottom-up measurements using methane sensors. On a similar note, detailed measurements from the Barnett shale region in Texas showed that just 2% of the facilities in the region account for 50% of all the methane emissions. Such a small fraction of large emission sources will further complicate direct measurements where typically only a small fraction of the facilities in a region are measured. While the EDF and other studies have been instrumental in our current understanding of methane leaks in the US and its contribution to greenhouse gas emissions, much work is required to understand sources, and most importantly, ways to cost-effectively monitor, detect and repair such leaks.

Aerial footage of the recent natural gas leak from a storage well in Aliso Canyon near LA. The leak is estimated to have released 96000 metric tons of methane, equivalent to about 900 million gallons of gasoline burnt and $15 million worth of natural gas. Source: Environmental Defense Fund, 2015.

Methane leakage in the context of global warming has only recently caught public attention – see here, here and here. In addition to greater awareness in business and policy circles, significant efforts are required to identify economically viable leak detection and repair programs. Currently, the industry standard to detect methane leaks include high-sensitivity but high-cost sensors, or low-cost but low-sensitivity infrared cameras. There is an immediate need to develop techniques that can be used to cost-effectively detect leaks over large areas (e.g. thousands of squared miles). From a regulatory perspective, EPA has released proposed regulations to limit methane leaks from the oil and gas industry. This comes on the heels of the goals set by the Obama administration’s Climate Action Plan to reduce methane emissions from the oil and gas sector by 40 to 45% from 2012 levels by 2025. These regulations require oil and gas companies involved in the entire natural gas life cycle to periodically undertake leak detection and repair procedures, depending on the overall leakage levels. The final rule is expected to be out sometime in 2016.

The success of the Clean Power Plan in reducing greenhouse gas emissions will significantly depend on the strength of the proposed regulations to curb methane leaks. We now have a better estimate of fugitive emissions (leaks) of methane from the US natural gas infrastructure. Concurrently, there should be a greater focus on developing cost-effective programs to detect and repair such leaks. It was recently reported that replacing old pipelines with newer ones in the gas distribution network in a city is effective in reducing leaks, and improving public safety. With a considerably higher global warming potential than carbon dioxide, methane has the potential to erode the climate benefits earned by switching from high emitting coal plants to low emitting natural gas power plants. Ensuring that does happen will take a coordinated effort and commitment from both the industry and government agencies.

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Arvind graduated with a PhD in Electrical Engineering from Princeton University in 2015 and is currently a postdoctoral researcher in Energy Resources Engineering at Stanford University. Somewhere later in grad school, he became interested in the topics of energy, climate change and policy. Arvind is an Associate Editor at Highwire Earth. You can read more about his work at his personal website.

Energy Efficient Buildings: The forgotten children of the clean energy revolution

Posted on by Highwire Earth

Written by Victor Charpentier

The world’s population will increasingly become urbanized. In the 2014 revision of the World Urbanization Prospects, the United Nations (UN) estimate that the urban population will rise from 54% today to 66% of the global population by 2050. Therefore it is no surprise that cities and buildings are at the heart of the 11th Sustainable Development Goal of the UN: “Make cities and human settlements inclusive, safe, resilient and sustainable”. With an ambitious time objective of 2030, the goal is set to improve the sustainability of cities and the efficient use of their resources.

The impact of buildings on the energy consumption

Energy consumption is often described in terms of primary energy – that is, untransformed raw forms of energy such as coal, wind energy, or biomass. Buildings represent an incredible 40% of the total primary energy consumption in most western countries, according to the International Energy Agency (IAE). A growing awareness of energy issues in the United States led the Department of Energy (DOE) to create building energy codes and standards for new construction and renovation projects setting requirements for reduction of energy consumption (e.g. revised ASHRAE Standard 90.1 2010 & 2013). The LEED certification created in 1994 by the non-profit US Green Building Council for the American building industry has proven that there is a private sector interest to recognize the quality of new buildings. The DOE’s building energy codes mainly focus on space heating and cooling, lighting and ventilation, since these are the main energy consumers in buildings. Great energy savings can thus be reaped from improving the performance of new buildings and renovating existing ones in these categories. Refrigeration, cooking, electronic devices (featured in category ”others” in Figure 1) and water heating, related to the occupants’ activity, are comparatively minor.

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Figure 1. Operational energy consumption by end use in residential (left) and commercial (right) buildings. Source: DOE building energy data book.
Energy end-uses play a significant role in driving energy transitions

Despite the regulatory efforts that have been implemented in the past decade, significant improvements remain necessary to reach the ambitious goals set by the UN. To help achieve them in the US, the DOE has listed strategic energy objectives in its 2015 Quadrennial technology review. One of them reads: “Increasing Efficiency of Building Systems and Technologies”. This report notes that in the case of lighting technologies, for instance, 95% of the potential savings due to advanced solid-state lighting remains unrealized due to lack of technology diffusion. This underlines the need for implementation incentives in addition to research and development in the field of building technologies.

In contrast with this dire need for investments in end-use innovation, scientists showed in a 2012 study that the current investment levels in energy related innovation are largely dominated by energy-supply technologies. Energy-supply technologies are those that extract, process or transport energy resources, while end-use technologies are those that improve energy efficiencies and replace pollutant energy sources when feasible with clean sources (e.g. electric buses in cities). The discrepancy is high between supply and end-use investments. End-use technologies only represent about 2% of the total investments in energy innovations, as shown in Figure 2 below.

The consequences are that buildings technologies receive less investment to finance R&D than they should. In addition, the study suggests that end-use investments provide greater return-on-investments than energy-supply investments. The reason for this misalignment is mainly political as public and financial institutions, and policy makers tend to privilege the latter. The authors of the study suggest that this may be linked to a lack of coherent influence or lobbying for the end-use sector in great contrast with large energy supply companies such as oil or nuclear companies. Thus, to make longer strides in reducing our carbon footprint from the energy sector this needs to change.

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Figure 2. Investments (or mobilization of resources) for energy technologies, energy efficiency improvements in end-use technologies (green), energy resource extraction and conversion separated into fossil-fuel (brown), renewable (blue), and nuclear, network and storage (grey) technologies. Source: Nature Climate Change, 2(11), 780-788.
Building energy efficiencies: application to the design of better building skins

One way of improving energy efficiency in buildings is by focusing on the design of their skins or envelopes, which shelter their inside from the conditions outside. As interfaces between the controlled interior environment of buildings and the weather variations on the outside, building skins regulate the energy flow between these two environments. High insolation through windows, for instance, can result in large energy consumption needed for cooling the building. The extreme case imaginable would be in a skyscraper with an all-glass façade in a moderate or warm climate. In fact, balancing the heat coming from the sun (mainly through the windows) represents in average almost 50% of the cooling load in non-residential buildings and more than 50% in residential buildings. The warming that climate change will bring to many regions around the world will also make this worse.

Conventional shading devices such as fixed external louvers and Venetian blinds (see examples in Figure 3) can have a strong impact on the reduction of cooling loads. If they are controlled correctly and regularly adjusted, the building’s annual cooling load can be decreased by as much as 20%. 

 

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Figure 3. Current shading systems often combine external fixed louvers (left) and interior Venetian blinds (right). Source: Unicel Architecture – Blindtex.

One can add an additional level of performance by making these skins adaptable such that they provide benefits under varying conditions (weather, urban context, occupancy) through the physical change of their geometry. Implementations of such adaptive building skins have demonstrated reduction of energy demand by as much as 51% and high efficiency in moderate to hot climates. For instance, the Al Bahr twin towers (in Abu Dhabi), seen on Figure 4, are a good example of modern building skin implementation.

 

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Figure 4. Dynamic façade of Al Bahr twin towers, Abu Dhabi, United Arab Emirates. GIF Source: CNN cited by https://www.papodearquiteto.com.br. Pictures’ Source: http://compositesandarchitecture.com/.

As those two systems demonstrate, there is great potential for these advanced shading systems and for building innovation in general, but their development is still slowed down by the lack of innovative policy and desire to invest in energy efficient building technologies.

Let’s get buildings on board with the energy revolution

Buildings do not get as much attention as automobiles or new technologies but they may be equally important in our long-term future. This is because the energy consumed for heating and cooling spaces, lighting, ventilation and others represents a very large part of our total energy consumption. However, there are solutions and fixes to this situation. Buildings have been greatly improved over the 20th century but we need to take them a step further to prepare better, more efficient homes and offices that will meet our new standards of living in a warming world. The facts call for stronger investment and political commitment. Let’s get buildings on board with the energy revolution!

 

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Victor is a second-year PhD student in the Department of Civil and Environmental Engineering advised by Professor S. Adriaenssens. His research interests lie in reducing energy consumption of buildings and elastic deformation of shell structures.