Carbon Impact: A Positive Outlook
The effects of climate change are attributed to a number of different factors, but the leading cause is the burning of fossil fuels, resulting in a rapid increase in global warming. As the world seeks alternative energy sources to alleviate the strain on our planet and provide energy security, it is vital to consider the sustainability of the available options. Considering that global cooking practices involving solid and fossil fuels independently constitute 2% of annual global carbon emissions, there is a huge opportunity for transitioning to healthy fuels (Source).
Bioethanol provides a low carbon option that not only improves energy security, but also contributes to better health and environmental outcomes. A deeper look at the carbon intensity of bioethanol feedstocks shows the potential positive outcomes that can result in expanding household use of this renewable fuel.
Carbon intensity
Carbon intensity is the measurement of how much carbon dioxide (CO2) is emitted as a result of the production and consumption of goods. It is commonly analyzed in life cycle assessments (LCA) of fuel and is generally characterized as the most important factor. LCAs are a common method used for measuring the impact of a product or service. When burned, pure biofuels generally produce fewer emissions compared to fossil-fuel counterparts that do not contain biofuel. Currently, the US and a number of other countries blend gasoline with bioethanol, which allows the fuel to burn cleaner and achieve higher octane levels without the addition of more harmful octane additives. When bioethanol is utilized as a cooking fuel in a cookstove, the amount of denaturant and/or hydrocarbon in the cooking fuel is very low or non-existent, resulting in clean combustion. This clean burning fuel also results in lower percentages of respiratory and cardiovascular disease that can result from household air pollution (HAP) caused by solid and fossil fuel use.
While it is accepted that the burning of biofuels results in lower carbon emissions than solid or fossil-based fuels, the process of bioethanol production requires additional consideration with regard to carbon intensity and sustainability. Ultimately, the carbon intensity of a biofuel is directly correlated to how that fuel is produced, the type of feedstock used, and the end use of the product. Let’s break that down.
Sustainable products
Undeniably, defining the carbon intensity of bioethanol is a daunting task and requires the consideration of all co-products and waste produced throughout the entire process. Where traditional gasoline is a byproduct of crude oil, bioethanol is generally produced through the fermentation of different feedstocks or bio-waste. Two of the most widely used feedstocks for bioethanol are corn and sugarcane. Both are grown, milled, and then proceed to fermentation with yeast and enzyme addition, ending with distillation to remove excess water from the final alcohol. The final products provide bioethanol for fuel use and typically additional coproducts such as high protein animal feed, corn oil and CO2.
The USDA states that corn based bioethanol results in up to a 43% reduction of greenhouse gasses over traditional gasoline (Source). Argonne National Lab’s GREET Model noted the number to be even greater than 40% and quoted sugarcane (without land use change) to have as high as a 70% reduction (Source). Even though these are remarkably more sustainable, it should be noted that the processes for producing bioethanol fuel require heat and electricity, and while producers are increasingly becoming more efficient, these are still commonly sourced from fossil fuels.
Feedstock considerations
When it comes to feedstock type, there is often variation in both the contribution analysis and total global warming potential. A contribution analysis on corn based bioethanol has indicated that the highest contributing factors to global warming potential (gCO2eqv.) in the creation of bioethanol are feedstock and fuel production, at 40% and 43% of the total, respectively. (Source). Sugarcane based bioethanol, on the other hand, uses around 67% and 7% for feedstock and fuel production, with transportation at 24% compared to corn bioethanol’s 5% (Source). The significant difference between the two is attributed to the “Well/Field to Pump” (W/FTP) and “Pump to Wheels” (PTW) stages of production and use between the three. Where conventional gasoline utilizes 17% of fossil fuels just in the WTP stage, corn and sugar based bioethanol use 100%. That difference is the result of fertilizer use in farming and energy use in production plants (Source). In other words, the carbon intensity is tied to farming practices and energy use amongst different feedstocks.
Regardless of whether the comparison is between energy density or carbon intensity, bioethanol is much more environmentally friendly than conventional gasoline. While this is known, there is the additional consideration of variability across agricultural practices, depending on the geographical region crops are grown in and farming practices utilized between different feedstocks. Further carbon intensity reduction, as a result, is closely tied to advancement and actual use of energy efficient technology.
Some governments, including the United States, have supported efforts to reduce greenhouse gas emissions and produce biofuels using methods that require less energy than conventional fermentation. One such effort is the utilization of cellulosic biomass, decreasing the need for large scale cultivation and other inputs like fertilizer, when compared to more traditional feedstocks like corn or sugarcane. Cellulosic bioethanol provides a future source of renewable energy that creates even greater advantages in efficient water and land use. Aside from technology advancements, there are a number of major producers and distributors exploring alternative options to reduce carbon intensity.
Producer engagement
POET – the global leader in bioethanol production – announced in the Fall of 2021 that by 2030 it was going to reduce its carbon intensity by 70 percent compared to gasoline, and achieve carbon neutrality at its facilities by 2050. Doug Berven, Vice President of Corporate Affairs at POET, emphasized that he believes biofuels have extreme promise, not only as a clean fuel opportunity around the world, but also in the advancement of biotechnology. While they will continue to work on process efficiency steps, POET also aims to look into a combination of alternative forms of energy, product diversification, and agricultural improvements that benefit farmers. In fact, carbon capture and sequestration technologies are being investigated at several bioprocessing facilities, and an on-site solar farm has been installed at the Headquarters in Sioux Falls.(Source)
Eco-Energy – the leading independent provider of biofuel supply chain management – is also striving to lower the carbon impact across all possible areas it touches. Eco-Energy handles 15%, or 2.4 billion gallons of bioethanol, via its midstream terminals and physical marketing activities. This large volume moves through a complex network of 11 bioethanol producer partners and more than 10 distribution facilities. This means carbon reduction can become slightly more difficult to implement uniformly, and is tailored to each individual asset or partner. Despite this hurdle, Eco-Energy is a leader in carbon reduction strategy across the United States. A recent interview with Eco-Energy’s CEO Craig Willis, revealed that these reductions are the result of a dedicated bilateral response to both upstream and downstream practices, particularly with a newly formed solar development team. On the downstream side, that response has led to the 2021 completion of the first two fuel terminals in the United States to achieve net-zero emissions for on-site operations. On the upstream side, the goal remains the same, but focuses on providing education and carbon solutions for bioethanol producers. While these solutions provide higher carbon savings, higher initial costs still tend to remain the limiting factor for many. In the meantime, sugarcane and corn are the most cost-effective and sustainable way to produce bioethanol.
The current production capabilities and future potential of bioethanol allow organizations like Pivot to continue working with partners to build access to affordable, sustainable fuels that positively impact human health, protect the environment, and improve climate outcomes.
