3 item(s) found.

Why it is so difficult to measure biofuel emissions

Why it is so difficult to measure biofuel emissions

Bunyod Holmatov

People’s use of energy around the world is increasing (WB, 2017). This is caused by a combination of factors such as a growing population, a higher concentration of people in urban areas and higher rates of industrialization (Johansson et al., 2012). Since the industrial revolution, most of the energy in the world has been obtained from fossil fuels that are, notably, linked to the release of greenhouse gas (GHG) emissions.

By now, there is widespread consensus among scientists that anthropogenic GHG emissions contribute to changing the climate by disrupting the planet’s inherent energy balance. Among all the sources of anthropogenic GHG emissions, energy production and use contributes the most – around two thirds (IEA, 2015), making the energy sector central to climate change discussions. Therefore, a transition is underway towards renewable energy obtained from “cleaner” sources such as the sun, wind, biomass, tides and so on.

Among different types of renewables, biofuels are of particular interest because they can emit less GHGs and make countries less dependent on oil imports and their volatile prices (Karatzos et al., 2014). In a little over two decades, between 1990 and 2014, emissions from the transport sector increased by 71% (IEA, 2016), and these emissions will continue to increase in the near future. The International Energy Agency (IEA, 2017) projects that under the current policies, emissions in the transport sector will increase by 17% between 2015 and 2040. Switching to biofuels can thus bring multiple long term benefits.

However, despite the general agreement that biofuels emit less than oil-derived fuels, the actual GHG emissions (for the same type of biofuels, i.e. bioethanol, biogasoline, etc.) may vary. The variation between studies emerges because of complexity of calculations that involve different inputs during the numerous production steps. Moreover, there is a distinction between the biofuels based on the type of feedstock. The so called “conventional” biofuels are produced using agricultural crops (i.e. sugarcane, sugar beet, etc.) while “advanced” refers to non-crop based biofuels (i.e. derived from biomass, algae, etc.; EC, 2016) that have not reached large commercial-scale production.

Calculating total GHG emissions of biofuels involves data from multiple stages of production, such as the crop cultivation (conventional biofuels) or extraction (advanced biofuels), processing, transport, and distribution. Each step can also have many sub-steps, i.e. producing “conventional” biofuels involves cultivating the crops that cover four main categories of inputs: (1) agro-chemical application; (2) field nitrous oxide emissions; (3) fossil fuel use; and (4) seeding material (Ecofys, 2010; EC, 2016). Thus, reported GHG emissions for the same type of biofuel can be different depending on where and how it was produced.

When discussing biofuels, it is important then to understand what type of biofuel is being discussed, what feedstock type, how it was produced (process route) and where. Sometimes, such as in the EU energy directive, the reported ranges also specify whether emissions of biofuels refer to “typical” GHG or “default” GHG. The former is an estimate that is typical in the EU while the latter is derived from the typical value using pre-determined factors (EC, 2016). In other words, factors such as the crop yield in Europe can be different from the specified ‘default’ crop yield.

The following examples demonstrate how biofuel type, feedstock type, and process route affect the GHG emissions of biofuels. “Conventional” bioethanol can be produced using a range of crops. Using sugar based crops such as sugar beet or sugarcane requires less processing steps because sugars are readily fermentable. This means that sugar based crops emit less GHGs than starch based crops such as maize, that require relatively more processing steps to convert them to fermentable sugars. Therefore, a typical emission of a “conventional” bioethanol produced from sugarcane is 28 g CO2eq/MJ and for sugar beet is around 31 g CO2eq/MJ. In contrast, a typical emission of maize based “conventional” bioethanol is around 49 g CO2eq/MJ (EC, 2016).

While both bioethanol and biodiesel are biofuels, biodiesel emissions are higher than bioethanol emissions. Typical GHG emissions of a sunflower based “conventional” biodiesel is around 40 g CO2eq/MJ. Using palm oil as the feedstock can increase typical emissions to 58 g CO2eq/MJ. It is important to note that the “default” GHG emissions can be even higher. For instance, palm oil based “conventional” biodiesel has a default emission of 70 g CO2eq/MJ (EC, 2016). At the same time, despite having higher emissions, biodiesel can be readily used in diesel cars whereas bioethanol has to be blended with a certain ratio of gasoline to prevent corrosion of car parts. 

“Advanced” biofuels are usually promoted for their dependence on non-crop feedstocks, while in reality, they also lead to less GHG emissions compared to “conventional” biofuels. For example, producing bioethanol from corn stover can lower emissions to 31 g CO2eq/MJ (IEA, 2013), whereas using wheat straw would typically emit 13.7 g CO2eq/MJ (EC, 2016). Similarly, using waste cooking oil to produce “advanced” biodiesel would typically emit 16 g CO2eq/MJ (EC, 2016).

In terms of process routes, they are more applicable to “advanced” biofuels than to “conventional” biofuels. The latter are produced using more established methods. In contrast, feedstock processing routes of “advanced” biofuels are still in development and their effect on GHG emissions are less clear cut. For example, converting wood residue to gasoline through the “pyrolysis” processing route can emit around 49 g CO2eq/MJ while choosing the “sugar catalysis” process only emits around 5 g CO2eq/MJ (IEA, 2013).

For practical reasons, biofuel’s GHG emissions are also compared to fossil fuel emissions to indicate the degree of emissions that can be ‘saved’ by switching to a given biofuel. To give some examples, approximately 87 grams of CO2eq emissions are emitted per MJ of oil based gasoline. In contrast, converting wood residue to gasoline can lower emissions to a range between 2 and 49 grams per MJ (depending on the process route) that translates to the GHG emission savings in the range of 98% and 43%, respectively (IEA, 2013).

In conclusion, many factors contribute to the GHG emissions of biofuels. General biofuel emissions always embody certain underlying assumptions related to the feedstock, process route, location specific conditions, etc. Addressing each and every assumption of biofuel production that can yield a certain cumulative GHG emission is challenging. Thus, from the policy making perspective, the old proverb “measure twice and cut once” is ever pertinent.


Johansson, T. B., Patwardhan, A. P., Nakićenović, N., & Gomez-Echeverri, L. (2012). Global energy assessment: toward a sustainable future. Cambridge, UK: Cambridge University Press.

Karatzos, S., McMillan, J.D., Saddler, J.N. (2014). The Potential and Challenges of Drop-in Biofuels. Paris, FR: International Energy Agency. 

EC. (2016). Proposal for a Directive of the European Parliament and of the Council: on the promotion of the use of energy from renewable sources (recast). Retrieved from: https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:52016PC0767R%2801%29

Ecofys. (2010). Annotated example of a GHG calculation using the EU Renewable Energy Directive methodology. Retrieved from: https://ec.europa.eu/energy/sites/ener/files/2010_bsc_example_ghg_calculation.pdf 

IEA. (2013). Advanced Biofuels – GHG Emissions and Energy Balances: A report to IEA Bioenergy Task 39. Retreaved from: https://www.ieabioenergy.com/wp-content/uploads/2018/02/Energy-and-GHG-Emissions-IEA-Bioenergy-T39-Report-May-2013-rev.pdf

IEA. (2015). Energy and Climate Change. Retrieved from https://www.iea.org/publications/freepublications/publication/WEO2015SpecialReportonEnergyandClimateChange.pdf

IEA. (2016). CO2 emissions from fuel combustion: highlights. Retrieved from https://emis.vito.be/sites/emis.vito.be/files/articles/3331/2016/CO2EmissionsfromFuelCombustion_Highlights_2016.pdf

IEA. (2017). World Energy Outlook 2017. Retrieved from https://www.iea.org/weo2017/

WB. (2017). Energy use (kg of oil equivalent per capita): World. Retrieved from http://data.worldbank.org/indicator/EG.USE.PCAP.KG.OE


Meeting EU biofuel targets: the devil is in the detail

25 March 2019

Meeting EU biofuel targets: the devil is in the detail

The Autonomous University of Barcelona team

Transport is one of the most unsustainable sectors in the EU: it lags behind all other sectors in terms of emission reduction, and alternatives have been tricky to find, monitor and implement. In 2016, just 3.8% of the energy consumed in the transport sector came from renewable energy sources (EUROSTAT, 2019). Electric vehicles are gaining momentum as a possible solution to sustainable transport, but so far they can only substitute road passenger vehicle, leaving a big gap for other forms of transport, such as shipping and aviation. Similar to electric vehicles, biofuels are seen as a solution to simultaneously lower emissions and lower dependence on imported oil. Following concerns over indirect land use change (ILUC), the recast renewable directive set strict criteria on the sustainability of biofuels, however they are still considered to be a central element to the sustainable transport transition. Differently from renewable electricity which is generated with local resources on the spot, and from fossil fuels that are extracted with associated environmental damage, biofuels represent a peculiar case of renewable energy, since, similar to fossil fuels, they rely on a multi-step process: first the cultivation of crops, and then their conversion to fuels, with intermediate steps depending on the type of fuel. This makes their accounting more complicated. With the EU setting rigorous sustainability targets for biofuel implementation, how can this sustainability be monitored when more than half of the feedstock used to produce biofuels in the EU is imported? (Buffet, 2017)

The fact that biofuels require multiple steps, and that steps can occur within different sectors and economic domain (first in agriculture and then in the energy sector) adds more layers to the openness of the system, and with each layer come difficulties in monitoring and accounting. Take the case of the Netherlands: between 2010 and 2015, the country quadrupled its consumption of residues of Used Cooking Oil (UCO) as a raw material to produce biodiesel. As it does not have an adequate local supply, it imported 81% of UCO, of which roughly 51% came from countries outside the EU (CE Delft, 2017). Following high impact media campaigns, it has become generally well known that palm oil production leads to biodiversity loss in Indonesia and Malaysia, a fact which led the EU to implement a strategy to reduce palm oil imports from Asian countries. However, the imports of UCO derived from palm oil are not limited, and if left unchecked a rise in UCO demand may lead to a rise in palm oil production. Another issue linked to the openness of the biofuel production chain is related to the double accounting mechanism, a political guideline included in the first EU renewable energy directive.

Following this guideline, the energy participation of certain residues of animal and vegetable origin are counted twice with respect to reaching the proposed objectives. What is problematic here is that not all countries have applied the guideline, and the difference in applicability has increased dynamics in waste trade. For example, Germany, which does not apply the double accounting mechanism, exports its animal fat waste to The Netherlands (where, in contrast, the double accounting principle is applied) (CE Delft, 2015). In addition, double accounting can lead to a "virtual" share of biofuels in the transport sector, which implies that this virtual percentage will be covered in the real world by another type of fuel, perhaps fossil fuels.

Biofuels are being pushed in the EU as a solution for increased sustainability and security of supply. They also generate a massive business: in economic terms, Charles et al., (2013) estimated that for 2011 the EU allocated between 9.3-10.7 billion euros to subsidize the use of conventional biofuels - a significant figure considering that the size of the biofuel market in the EU for that year was around 13-16 billion euros. Each EU country has varied agricultural production capabilities, and setting uniform targets across all member states may push governments to import feedstock to locally produce biofuels, or to see this as a business opportunity to import and export biofuels, like The Netherlands is doing. If the EU is serious about the sustainability of it transport fuels, it should account for all steps of the biofuel production process, and regulate the trade of primary and secondary products to avoid turning biofuels into a business opportunity with little positive impact on the environment.


Buffet, L., 2017. Realitycheck-10 things you didn’t know about EU biofuels policy.

CE Delft, 2017. Sustainable biomass and bioenergy in the Netherlands Report 2016. Delft.

CE Delft, 2015. Biofuels on the Dutch market Update: data for 2013. Delft, The Netherlands.

Charles, C., Gerasimchuk, I., Bridle, R., Moerenhout, T., Asmelash, E., Laan, T., 2013. Biofuels: At What Cost? A review of costs and benefits of EU biofuel policies. Int. Inst. Sustain. Dev.

EUROSTAT, 2019. Data base - EUROSTAT [WWW Document]. URL http://ec.europa.eu/eurostat/web/main/home (accessed 2.4.19).

Giuntoli, J., 2018. Advanced Biofuel Policies in select EU Member States: 2018 Updated.

Photo credit: United Soybean Board

Biofuels at a crossroads: the concerns are stacking up

Biofuels at a crossroads: the concerns are stacking up

Maddalena Ripa, Mario Giampietro, Juan José Cadillo Benalcazar

The International Energy Agency reports that ‘modern bioenergy is the overlooked giant within renewable energy.’ In the United States, as in many OECD countries, emissions from electricity generation are no longer the top contributor to climate change: the first position in terms of carbon emissions now belongs to cars and trucks. The Intergovernmental Panel on Climate Change (IPCC, 2018) recently reported that electricity’s involvement in the transport mix should increase to 1.2% in 2020, 5% in 2030 and 33% in 2050, meaning that by 2030 biofuel-powered vehicles would still be as important as e-cars.

Biofuels are therefore at a crossroads. In the EU28, biofuel consumption in the transport service has grown more than six fold over the last decade, however biofuels still account for just three to four percent of all transport fuel energy.  What are the concerns related to the plausibility of a fast and effective expansion of this option?

1. Around half of the EU’s production of crop biodiesels is based on imports of feedstock, not crops grown by EU farmers (Transport & Environment, 2017)

Over the years 2000-2016, the production of biofuels in EU28, especially biodiesels, has increased exponentially in EU28.  However, imports and exports associated with biofuels increased as well, especially in countries like The Netherlands. This scale-up adds another level of complexity, making it difficult to get a clear picture of the situation: to what extent is the production of biofuels in the EU aimed at lowering emissions, and to what extent is it a mechanism aimed at profiting on subsidies?  Looking at the feedstock mix, only 47% of the feedstocks were grown in the EU for EU production in 2015, meaning that over half the feedstock mix was imported (EC, DG AGRI, 2016). Evidence for this can be found in the different oils used in the EU: in 2016, according to OilWorld, 33% of EU vegetable-oil biodiesel came from imported palm oil. Rapeseed still remains the most used raw material (around 60%). This is also true for Used Cooking Oil (UCO): according to the European Commission DG AGRI Medium-Term Agricultural Outlook, 56% of raw materials used for the production of biodiesel in Europe originated from within the Union in 2015. However, this figure assumes that waste oil is all domestic, which is incorrect. Imported used oils mean it is likely that less than half of the biodiesel supply is from EU production. 

2. There is debate about whether biofuels represent a net energy supply (i.e., whether biofuels require more energy inputs in their production phase than what they provide).

The process of growing crops, manufacturing fertilizers and pesticides, and processing plants into fuel consumes a lot of energy. At the moment, most of the energy used in the various phases of production comes from oil, coal and natural gas (fossil energy). This implies that the assessment of the net energy supply of biofuels is still quite controversial. Endless discussions and a large amount of scientific publications have been dedicated to this issue.  For example, various studies have estimated the EROI (Energy Return on Investment)  of corn ethanol at between 0.8:1 and 1.7:1, meaning that we get between 0.8 and 1.7 joules of energy from ethanol for every joule of energy invested in producing that ethanol. The EROI of gasoline, by comparison, is between 5:1 and 20:1, depending in part on the source of the petroleum (Hall et al., 2011). However, the general agreement is that, when compared with the production of fossil fuels, the energetic convenience of producing biofuels is much lower, even less in case of advanced biofuel (Forbes, 2018).

3. Total life-cycle greenhouse gas emissions from biofuels are virtually impossible to measure

While ‘direct emissions’ can be lower for biofuels (if one agrees on how to calculate the net supply), the assessment of ‘indirect emissions’ are elusive.  Greenhouse gases (GHG) are emitted throughout various stages in the production and use of biofuels: in producing the fertilizers, pesticides, and fuels used in farming, during chemical processing, transport and distribution, up to final use. This process involves a significant amount of fossil energy uses along the entire supply chain that can make biofuels less environmentally friendly than petroleum-based fuels. In relation of indirect emissions, the elephant in the room is represented by the potential increase of overall GHG emissions due to indirect land-use change (ILUC) – e.g. the controversy over palm oil.  Indeed, when considering in the assessment the effects of land-use changes, the claim that biofuels do imply a reduction of emissions becomes very difficult to defend.

4. What about aviation?

Between 2005 and 2017, carbon dioxide emissions increased by 16% and nitrogen oxide emissions went up by 25%, according to the second European Aviation Environmental Report (EAER). Specific to aviation, total GHG emissions were projected to increase by 400%–600% between 2010 and 2050, based on projected growth in travel (ICAO, 2013).  In relation to the growing concern for this specific typology of liquid fuels, the potential use of biojet kerosene is very limited because of the higher cost compared with petroleum jet fuel. There are several initiatives to promote aviation biofuel, such as higher subsidies,  but…as the International Air Transport Association forecasts the 3.8 billion air travelers in 2016 to double to 7.2 by 2035,  the question arising is: is there enough land available to produce biojet fuel?

5. There isn’t adequate technological infrastructure to produce advanced biofuels in the EU

In the effort to decarbonise the transport sector, EU Member States recently decided to revise the Renewable Energy Directive (RED II) setting an obligation for Member States to ensure the achievement of 14% Renewable Energy Sources (RES) in transport by gradually phasing out crop-based biofuels (from 7% in 2020 to 3.8% in 2030) and boost 2nd and 3rd generation biofuels.  However, the production of advanced biofuels from non-food crop feedstocks is still limited. Biodiesel and HVO (Hydrotreated Vegetable Oil) from waste oil and animal fat feedstocks is around 6-8% of all biofuel output and is anticipated to remain modest in the short term, as progress is needed to improve technology readiness (IEA, 2019).

6. There is an acute lack of transparency about the biofuels used in the EU

Data about biofuels can generate confusion in relation to three main points:

  • What ‘biofuels’ are we talking about? - the label may refer to liquid fuels, biogas or wood pellets. These three different forms have very different functions – wood pellets, for example, cannot be used to power a car.  Summing up these three different energy forms into an overall estimate should be avoided because the overall number generated by summing ‘apples’ and ‘oranges’ does not have any policy relevance and muddles the discussion;
  • What 'primary source' are we talking about? - production can be based on two different processes. The first is the actual production of biomass. This type of primary source entails constraints on supply related to the availability of land, water and the ecological sink capacity for technical inputs. A second process is the valorisation of wastes. Here, we are dealing with ‘secondary sources’ leading to constraints on the supply determined by the availability and the cost of collection of the waste. Addressing this difference is essential to estimate how much the given supply of biofuels can be scaled-up when looking for a substitution of the actual consumption of oil;
  • Accounting of imports - imports of biofuels ‘energy carriers’ vs imports of feedstocks ‘primary sources’.  The emissions associated with the processes taking place in the countries generating the imported inputs are often neglected in local assessments. Moreover, double counting was included in the RED I (art. 3f) and was applied to the advanced or second-generation biofuels. Double counting means, for instance, that if molasses consumption is 2%, it will be counted as 4% of the total energy used in transport.   

With growing fuel demand in the transport sector, all these controversies surrounding biofuels should deserve attention at the science-policy interface.



European Commission, DG AGRI Medium-Term Agricultural Outlook 2016-2026

European Commission, 2016. Second European Aviation Environmental Report https://ec.europa.eu/transport/sites/transport/files/european-aviation-environmental-report-2016-72dpi.pdf

Forbes, 2018. The Ethanol Debate Matters, But Is Unlikely To Change. https://www.forbes.com/sites/joshuarhodes/2018/02/25/the-ethanol-debate-matters-but-is-unlikely-to-change/#648485c65e26

Hall C., Dale B. and Pimentel D., 2011. Seeking to Understand the Reasons for Different Energy Return on Investment (EROI) Estimates for Biofuels. Sustainability 3: 2413-2432 doi:10.3390/su3122413. 

International Energy Agency, 2019. Biofuels for transport. Tracking Clean Energy Progress https://www.iea.org/tcep/transport/biofuels/

International Civil Aviation Organization (ICAO), 2013. Environmental Report: Destination Green.

IPCC, 2018: Global warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [V. Masson-Delmotte, P. Zhai, H. O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J. B. R. Matthews, Y. Chen, X. Zhou, M. I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, T. Waterfield (eds.)].

Transport & Environment, 2017. Reality check - 10 things you didn’t know about EU biofuels policy. https://www.transportenvironment.org/publications/reality-check-10-things-you-didn%E2%80%99t-know-about-eu-biofuels-policy

The energetic convenience is commonly intended as EROI (Energy Return On Investment) which is the energy returned from an activity compared to the energy invested in that process. The basic equation is: EROI = Energy gained from an activity/Energy used in that activity. Any time the EROI is less than 1:1, it takes more energy to produce the fuel than the fuel contains.