Biofuels - A Viable Option?

Picture by: Oxfam on Flickr

The impact of biofuels option on climate change has been another area of immense debate.

Supporters of biofuels consider it a carbon-neutral option. The carbon that would be released arising from its use, should theoretically not exceed the amount earlier absorbed through photosynthesis. Life cycle analysis (LCA) studies conducted in the early 2000s generally demonstrated the potential of biofuel in reducing Global Warming Potential (GWP), as compared to fossil fuel use.

GHG Emissions (gCO2-eC m^2/yr)
Source:  Adler et al (2007)

The LCA conducted by Adler et al (2007) on biofuel cropping systems suggested that ethanol and biodiesel from crop rotations reduced greenhoue gas (GHG) emissions by between 40-115% as compared to the life cycle of gasoline and diesel.

An earlier LCA study by Spath and Mann (2004) also illustrated that producing electricity from biomass instead of fossil fuels with CO2 sequestration, can be a cost effective solution in reducing GHG emissions.

However, recent studies have asserted that biofuels may not be as carbon neutral as we have assumed. Indirect carbon emissions arising from landuse change were not factored in earlier LCAs that could have major impact on the climate. Fargione et al (2008) suggested that converting natural habitats such as peatland and savannas to produce food crop–based biofuels creates a “biofuel carbon debt” by releasing 17 to 420 times more CO2 than GHG reductions from fossil fuels avoidance arising from biofuel use.

Greater biofuel production might also decrease overall energy prices, leading to an increase in energy consumption and GHG release.

Holtsmark (2011) analysed the production of wood-based biofuels and concluded that the increased harvest of a boreal forest will create a biofuel carbon debt that takes 190–340 years to repay, and thus would not constitute a climate-neutral option.

Apart from landuse, the issue of indirect emissions was raised by Melillo et al (2009) who argued that increases in fertilizer use leading to more nitrous oxide emissions will be more important than carbon losses themselves in terms of warming potential.

Schulze et al (2012) also cautioned that biofuels production could result in a reduction of biomass pools that may take decades to centuries to be paid back by fossil fuel substitution. Depleted soil fertility will make biofuel production unsustainable and require fertilization, which in turn increases GHG emissions due to N2O emissions. The IPCC has listed N2O as having a GWP that is 310 times more that CO2 over a 100-year timeframe.

Apart form the science, the paper by Gasparatos et al (2013) suggested that there are still many areas of social-economic and environmental areas of concern that needs to be addressed in relation to biofuels production, such as rural development, biodiversity loss and water pollution. For example, the Guardian in October 2013 reported that campaigners condemned new UN recommendations on biofuels, claiming that they defend the interests of the industry rather than those of small farmers in poor countries.

These add on to the myriad range of considerations behind the sustainability of biofuel as a climate change mitigation alternative.

On balance, I believe that biofuels offer an option to diversify the energy mix for societies that may be constrained in terms of natural resources, contributing towards energy security. However, biofuels bring along a set of social and economic issues such as food security that would decision makers would need to consider. There may also be a need to consider more robust forms of life-cycle analysis that takes into consideration indirect CO2 emissions arising from areas such as land use change and fertiliser production, so that a more comprehensive assessment can be made to determine the carbon-neutrality of biofuels.

Reality Check

The New York Times has recently published the illustration below on how China and the US are faring in terms of renewable energy generation and fossil fuel use for the past years.

It appears that China has been rather aggressive in its renewal energy growth, in particular for wind (82%) and solar (85%) technologies. Nonetheless, there has also been an increase in fossil fuel consumption such as natural gas (19%) and coal (8%).

On the other hand, while the US may be experiencing slower growth in its renewable energy sector relative to China, the US has been able to curb fossil fuel consumption for coal and oil at a 2% annual rate of reduction.

As we consider the issue of energy use and its impact on climate change, the statistics could help provide a glimpse of the different approaches that some of the major economies have undertaken to reduce carbon emissions, either through renewable energy promotion, or by reduction of fossil fuel consumption.

Chart by Bill Marsh of New York Times
Information source from US Energy Information Administration

Perception of Shale

In September 2013, UK Secretary of State for Energy and Climate Change, Edward Davey supported the safe and responsible exploration of shale gas in the UK, in line with UK’s climate change targets. He believed that shale gas, as the cleanest fossil fuel, would be help in UK's efforts to move away from coal.

Meanwhile, a Telegraph report mentioned that debate within EU countries remains highly polarised, with countries such as France, Bulgaria, Denmark and the Czech Republic either banning exploration or planning to do so. Within the European Commission, opinion was divided between the need for firms to do more to track methane emissions, and the view that Europe's energy industry cannot be sacrificed at the expense of unrealistic climate change goals.

Photo by: Bill Baker on Flickr

A study conducted by Rabe and Boric (2011), based on a survey conducted on residents in Pennsylvania, suggested that public views on fracking could be positive. The people generally believed that the benefits arising from the shale gas extraction out-weighed cost. Interestingly, the survey revealed that there was general distrust in the authorities on the issue. 

In another study on public perception of communities near shale gas locations, Theodori (2009) found that respondents generally felt that the shale gas operations had contributed towards worsening traffic conditions and competition for freshwater resources. Nonetheless, respondents also acknowledged the improvement in economic and service-related areas such as healthcare arising from such developments.

In my last post, we had a glimpse of how scientists remain divided over the carbon dioxide and methane's mitigation potential arising from fracking operations. Politically, various countries have taken differing stance towards adoption of the fracking technology. The surveys discussed in this post on public perception appeared to be rudimentary studies, and more work remains to be done in order to better understand the communities' sentiments towards shale gas extraction. 

Fracking will likely remain controversial for some years. Meanwhile, I would suggest that it may be prudent for policy makers to consider taking a more conservative position on shale gas extraction, while awaiting for the scientific community and the industry to ascertain the risks and benefits of fracking. 

Shall We Rely On Shale?

Hydraulic fracturing or “fracking” is a technique that creates narrow fractures in rock using water pumped at high pressure so as to extract pockets of natural gas. The water contains small quantities of chemicals and sand to facilitate the process.  

While some may consider natural gas as a means of reducing CO2 emissions in comparison to coal, its extraction through fracking has attracted a fair share of controversy on issues such as its potential to create geological instability and ground water contamination.

The figure below illustrates a typical fracking process. 

Illustration by Wikipedia

From the climate change perspective, many have questioned if fracking is truly able to mitigate CO2 emissions. 

Mackay and Stone (2013), in a report commissioned by the DECC titled "Potential Greenhouse Gas Emissions Associated with Shale Gas Extraction and Use" in September 2013, concluded that the net effect of shale gas production on UK greenhouse gas emissions will be relatively small, with the right safeguards in place.

They calculated that the carbon footprint of shale gas extraction and use is likely to be in the range 200 – 253 g CO2e per kWh, which is lower than that of Liquefied Natural Gas (233 - 270g CO2e/kWh). For electricity generation (see chart below), shale gas' carbon footprint (423 – 535 g CO2e/kWh) is also significantly lower than coal (837 – 1130 g CO2e/kWh).



Comparison of the life-cycle emissions for the production of electricity from various sources of gas, and coal.

Chart from DECC Report titled "Potential Greenhouse Gas Emissions Associated with Shale Gas Extraction and Use"

There has nonetheless been divided scientific opinion on the rate of greenhouse gas (GHG) emissions arising from fracking. Apart from CO2, the other GHG of concern is methane. According to the IPCC, methane has a global warming potential 21 times greater than CO2, based on a 100-year time horizon. 

For example, there has been an exchange of opinion between Cathles et al (2011) and Howarth et al (2011, 2012) on the life cycle emissions on shale gas. Howarth et al (2011) had proposed that shale gas has a larger GHG footprint than coal. Catheles et al (2011) subsequently raised queries on Howarth el al (2011)'s methodology and results, such as its estimates on the methane gas release. Howarth et al (2012) followed up to published a response which included a comparison of methane release from life cycle analysis shale gas across various studies to substantiate his findings (see table below).




Comparison of published estimates for full life-cycle methane emissions from conventional gas and shale gas, expressed per unit of Lower Heating Value (gC MJ−1).

Table from Howarth et al (2012)

It may be interesting to note that Mackay and Stone (2013)'s DECC report commented on Howarth et al's study as being "considered by many to be an outlier" through the chart below.

Gas volumes released during well completion versus respective studies

Chart from DECC Report titled "PotentialGreenhouse Gas Emissions Associated with Shale Gas Extraction and Use"

While studies seem to suggest that GHG emissions arising from fracking are not substantial, I am of the opinion that various operational risks, such as the probability of drill well cracks leading to fugitive GHG release, may not have been examined in detail thus far. More studies would be needed to validate claims on the potential for shale gas extraction as a means to mitigate climate change.

Not withstanding the vibrant debate that will continue to take place within the scientific community, it would be prudent that the existing shale gas industry commits itself to work closely with regulators and ensure that the highest level of safety is practised, through adopt the principle of reducing emissions to as low a level as reasonably practicable (ALARP) in its operations as recommended in the DECC report. Public opinion will also be a key factor that policy makers and industry players have to manage moving forward, given the controversies that fracking has raised. 

How did it all start?

Photo by José Luís Agapito on Flickr

So when did mankind started our reliance on fossil fuels?

The first significant use of fossil fuels, as postulated by Steffen et al (2011), was in China during the Song dynasty (960–1279), primarily in its usage of coal to support the iron industry. England subsequently overtook China's fossil fuels usage by the 1600s, burning around 360,000 tonnes of coal annually. Nonetheless, CO2 atmospheric emissions were not massive then. 

Subsequently, the industrial revolution in the 1800s saw energy use grow by about 40-fold and economic production by 50-fold. The subsequent "Great Acceleration", as termed by Steffen et al (2011),  saw human population increase from 3 to 6 billion in just 50 year with a rise of 15-fold in economic activity. Fossil fuel consumption has since grown on an upward trajectory, resulting in carbon emission levels illustrated by the chart below. 



Chart by Carbon Dioxide Information Analysis Centre (CDIAC),
funded by US Department of Energy

With industrialisation and urbanisation taking place at such a rapid place, Ellis (2011)  argued that humans may have irreversibly altered the terrestrial biosphere through our activities. Amongst others, the use of fossil energy to replace biomass fuel and human and animal labour was likely one of the key contributing factors

Here's a video clip that summarises for us in 300 seconds, mankind's history of using fossil fuels in the last 300 years. 

The 2°C Target

In a report by the Guardian in July 2013, Swedish scientists have asserted that limiting carbon emissions to achieve no more than 2 °C rise in global temperature, would not be enough to stop potential problems such as biodiversity impacts, sea-level rise, or halt the acidification of the oceans.

Some of us may also be familiar with the 2 °C target that has often been cited by governments in UNFCCC negotiations. This leads one to wonder why 2 °C? 

Building on the work of the German Advisory Council on Global Change (WBGU) in 1995, Bruckner and Schellnhuber (1999) suggested that to prevent shut-down of the North Atlantic thermohaline circulation (which plays an important role in bringing heat to the polar regions), global mean temperature change should be kept to less than 2 °C relative to the pre-industrial level. 

Illustration by Wikipedia

In light of this background, there may be some basis to the scientists claim that more ambitious targets may be needed, since there are many potential impacts apart from polar ice melt that could arise due to global warming. 

This thus leads us to the next question. How far down are we in terms of mankind's fossil fuel emissions with respect to the 2°C Target ? 

The 5th assessment report (AR5) of the IPCC calculated that the combustion of fossil fuels (coal, gas, oil, and gas flaring) and the production of cement have resulted in 365 GtC being released to the atmosphere between the period of 1750 to 2011. Cement production constitutes about 8 GtC to this value. 

The other major contribution comes form land use change activities, mainly deforestation, which released an additional 180GtC . 

The combined fossil fuel and land use change emissions make up the bulk of anthropogenic carbon emissions. 531 GtC of anthropogenic carbon was emitted by 2011.

For a more than 50% probability of limiting warming to less than 2°C (since the period of 1861–1880), IPCC thinks that CO2 emissions from all anthropogenic sources will need to be limited to 840 GtC. 

The video below from "Shrink that footprint" provides a simple illustration of what this may all mean. 

We are indeed nearing the upper limits of the 2 °C guard-rail. Fossil fuel use, being the major contributor, would be a key area that would deserve our attention in our bid to better understand how measures can be taken to minimise its impact on global warming.

Consider this...

Photograph by Skip Brown, National Geographic

Mankind's relentless pursuit for energy sources has sparked a long-standing debate on how we have impacted our planet through global warming.

The 5th Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) released on 27 Sep 2013 opined that warming of the climate system is unequivocal. CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions.

Faced with mounting scientific evidence, many may feel the need for societies to rethink its approaches towards sustaining economic growth and development, and whether there are suitable climate-friendly alternatives to fossil fuels.

Being bred from a tiny Singapore island (smaller than half of London's land area), which is devoid of natural resources, has also led me to appreciate the fine balance between energy security and environment protection.

The UK Department of Energy and Climate Change (DECC) and the Carbon Trust had earlier embarked on a series of events entitled the "British Energy Challenge" to consider the various options affecting the demand and supply of energy for the UK. How everyday decisions could be turned into potential opportunities to mitigate the effects of global warming were also explored.

Through this blog, I hope to likewise embark on a journey to examine the relationship between energy and climate change. Hopefully we can come to some conclusions on the essential factors behind an energy mix that would meet urban cities' developmental needs, while balancing our aim of minimising impact on the earth through global warming.

Do stay tuned for more.