© chokniti @ stock.adobe.com
Our carbon-intensive economy is facing a crisis as we start to feel the effects of global warming and climate change, yet we continue to pursue growth. Global demand for transportation-related energy is projected to increase about 25 percent by 2040. Uncoupling from fossil fuels and accelerating the reduction in emissions from all sectors, and in particular, the transportation sector will play a critical role in reducing global greenhouse gas emissions. In 2020, a spate of incidents related to Very Low Sulphur Fuel Oil (VLSFO) —or "Frankenstein fuels"— drew sharp attention to the need for sustainable alternatives. The question is, can biofuels ever meet the global energy demand?
Transitioning Global Energy Use
Since the dawn of civilization, mankind has capitalized on biofuels. Wood and charcoal, the original biofuel, have been used by humans for millennia. More recently, we have relied on hydrocarbon compounds derived from coal and crude oil (fossil fuels), and to lesser extent biofuels such as alcohol and ethanol.
Fossil fuels are produced as a result of geological processes and the decomposition of carbon-based organisms typically millions of years old. When any carbon-based fuel is burned, CO2 and other greenhouse gases are released into the atmosphere to create the effect known as global warming. In the last 150 years, this has accelerated, and now greenhouse gases are at their highest level for the past 800,000 years. As temperatures creep up, we are approaching a dangerous global tipping point.
The major contributors to CO2 emissions —and therefore global warming— are the power, industry, residential, and transport sectors, together accounting for 90% of all CO2 emissions. Crude oil is a big player in this, responsible for about one-third of the world's total carbon emissions. In order to limit further global warming and slow the effects of climate change, the race is on to find suitable clean and renewable alternatives.
2020: the Anomaly
Restrictions and lockdowns imposed in a bid to contain the COVID-19 pandemic had a significant impact on the economy, which resulted in a temporary contraction of CO2 emissions. According to the International Energy Association (IEA), global energy demand fell by 6% in 2020, the largest contraction in 70 years. Global CO2 emissions are expected to decline by 8%, or almost 2.6 gigatonnes (GT), to levels from 10 years ago. But as seen with previous events such as the 2008 global financial crisis, it is expected that the rebound in emissions may be larger than the decline.
While 2020 was dominated by news of the pandemic, the shipping industry became plagued with the scandal surrounding the use of VLSFO. While global shipping is the world's sixth-largest contributor to carbon emissions, in 2015 the global body that regulates the shipping industry, the International Maritime Organization (IMO), chose not to comply with the Paris Climate Agreement, citing its importance to global trade. Following protests from environmental campaign groups and NGOs, the IMO, in what was largely seen as a 'bait and switch' greenwashing exercise, announced it would focus instead on reducing sulfur emissions. Rather than seek greener fuel sources or invest in 'scrubber' technology, the IMO implemented a ban on ships not using low-sulfur oil. However, such a fuel did not yet exist, and the result was thousands of permutations of toxic and unsafe experimental chemical and fuel mixtures coming onto the market.
Rapid adoption throughout 2020 led to a spate of disasters ranging from engine failures to shipping disasters, including oil spills, as was first reported in Mauritius in August 2020. The concoctions are so hazardous that the oil has been labeled a super-pollutant, and emit higher CO2 emissions than traditional Heavy Fuel Oil. This is not a small issue either: it affects 70% of ocean-bound ships. Ultimately shipping needs to transition away from its dependence on fossil fuels towards a cleaner alternative.
The Role of Biofuels
Because biofuels can be produced from plant matter, they are considered a renewable energy source and a sustainable alternative for the future. Growing crops for biofuels can take anything from 6 hours to 20 years and are far more easily replenished.
The first generation of biofuels derived from bioenergy crops, most commonly sugarcane and corn. Second-generation biofuels are produced from vegetable and animal waste streams, or discarded biomass, such as bioethanol, biodiesel, and biogas. The remainder of this case study will focus on third-generation biofuels; algal biofuel.
Algae contain a high amount of fatty molecules, or lipids, similar to vegetable oils. These fats can be converted into biofuel that can act as a drop-in replacement for petroleum-based gas, diesel, and jet fuel. Algae can be cultivated in an Algal Photobioreactor and algal oil is then produced in biorefineries or by using methods such as hydrotreating and hydrocracking to rupture the cell structure of microalgae and then using either solvents or sound waves to extract oil.
When considering algae for biofuel, the most common types are diatoms, green algae, golden brown, prymnesiophytes, eustigmatophytes, and cyanobacteria. However, cyanobacteria are not algae but a class of photosynthetic bacteria that can thus be refined to become biofuel too.
There are significant advantages to producing and using algal biofuel. As a single-celled organism, algae grows very quickly, with some species doubling in as little as six hours. It also does not require valuable arable land and therefore does not compete with food production. Strains can even grow in saltwater and wastewater, taking pressure off freshwater resources, and even serving Bioremediation methods such as biosorption or neutralization of toxic chemicals. Production is possible in open ponds (raceways) or closed-loop systems such as Algal Photobioreactors. Growing algae in such tanks could produce up to 60 times more oil per acre compared to land-based plants.
Algae is also a carbon sink, responsible for 40% of the global carbon fixation. With an estimated greenhouse gas footprint that is 93% less than conventional, petroleum-based diesel, it represents a significantly cleaner fuel alternative.
US-based MicroBio Engineering (MBE) is specialized in the design and construction of algae ponds for biofuel production, as well as producing algae-based animal feeds, other specialty products, and wastewater reclamation.
Solazyme creates high-performance algal biofuels that burn cleaner and perform better than petroleum-based fuels. Soladiesel BDR is a 100% algae-derived biodiesel which can be used with factory-standard diesel engines without modification. The fuel is fully compliant with the ASTM D 6751 specifications for Fatty Acid Methyl-Esther (FAME) fuel that meets ASTM D 975 and significantly outperforms ultra-low sulfur diesel in total THC, carbon monoxide, and particulate matter tailpipe emissions.
Since 2009, Synthetic Genomics and Exxon Mobil have been collaborating on research programs to develop biofuels from algae. Current programs are seeking to scale algae production to have the technical ability to produce 10,000 barrels of algae biofuel a day by 2025 —a self-confessed ambitious target, which is currently the largest algae growth pond in use with about one acre in size.
Can Biofuels Meet Global Energy Demand?
Algae certainly appeals as a biofuel. With a high-growth rate, and yielding nearly five times more biofuel per acre than plant-based biofuels such as sugar cane or corn, there is potential for biofuels to feature in our future energy mix. As a drop-in, algal biofuel could easily become a staple in transportation fuels. The IEA estimates that biofuels will comprise 6% of fuel use by 2030, although this could increase if the cost of crude oil also increases, or if more economically viable processing methods of algal biofuels are identified.
But there are still challenges to overcome.
For algal biofuel, in particular, the challenge is primarily an economic one. Fuel extraction and processing methods such as hexane extraction and supercritical CO2 fluid extraction are expensive and resource-intensive. According to a 2010 research study, producing fuel from algae grown in ponds at scale would cost between $240 and $332 per barrel, although some estimates price it at as low as $84. Given the current price of a barrel of crude oil is currently $52, it is easy to see why we have not made the switch yet.
Land use is also an issue, as to produce algal biofuel at the scale required would need significant land take. The daily demand for crude oil in 2021 is predicted to be 97.1 million barrels, and by 2040 this is expected to reach 150 million barrels per day. Global production of algal biofuel is currently around 2,000 barrels, and it is estimated that 30 million acres would be required for algae production just to meet the US demand for oil alone.
Like any crop, algae can be invaded by pests and pathogens, and therefore crop protection is a significant challenge when it comes to the viability of algal ponds and algal biofuels. Identifying strains resistant to pathogens through CRISPR could be demanding.
Further, as we head towards peak phosphorus, the point in time at which the maximum global phosphorus production rate is reached, algal biofuel production, not to mention agriculture, which both rely heavily on phosphorus for fertilizer, face a serious crisis. To succeed, large-scale algae production will need to either find alternative sources, or find ways to reduce, recycle and reuse existing phosphorus resources.
Even if it were possible to produce 10,000 barrels a day, this is a drop in the ocean. As it stands, algal biofuels can not yet compete with crude oil, but the race to find an economically viable solution is on.