University of Utah chemical engineers have developed a new method of producing biomass fuels which could make the whole process quicker, cheaper and more efficient.
Producing biofuels from microorganisms is certainly not new, with initial experimentation regarding the subject kicking off as early as 1942. Interest would wax and wane over the years - especially during crises regarding traditional fossil fuels - but despite extensive research and funding, no one had ever been able to make biofuel production profitable, both in terms of cash and energy.
Microorganisms, such as algae, can be turned into biofuel through the extraction of fatty acid contained in biomolecules known as lipids. Extracting this fatty acid traditionally required removing all the water from the microorganism, resulting in a dry powder or biomass slurry. This biomass is then placed into a solvent, which separates out the oil-rich lipids and produces a precursor to biocrude oil. Once mixed with diesel fuel, the substance - known as biodiesel - can then be used to power vehicles and generators.
The main drawback to this method is that the amount of biofuel gathered at the end is often less than the amount of energy expended to produce it, with the dehydrating process in particular demanding high energy requirements. Not only does this mean biodiesel is less efficient from a resource perspective, it also results in a more expensive end commodity, making it less attractive to consumers and dependant on heavy subsidisation.
Creating Jet-Powered Biofuels
The University of Utah team’s method of producing biofuel from algae, however, looks to not only speed up the process, but also make it less energy-dependent and ultimately cheaper. The process, as outlined in the new peer-reviewed journal, Chemical Engineering Science X, does away with the lengthy process of dehydration, and instead uses a new kind of jet mixer to extract the lipids in seconds.
Within the jet mixer reactor, jets of solvent are fired at jets of algae, creating a localised turbulence in which the algae’s lipids make a short ‘jump’ into the stream of solvent. The lipid oil is then separated, and the solvent reused to repeat the process. Although still not ‘profitable’ in terms of energy output, the experimental University of Utah system is much closer to energy parity than previous methods and could become an important element of refining the production of biofuels from microorganisms. Co-author of the paper, Professor Swomitra “Bobby” Mohanty, stated:
“There have been many laudable research efforts to advance algal biofuel, but nothing has yet produced a price point capable of attracting commercial development. Our designs may change that equation and put algal biofuel back in play.”
Business and governments have indeed been keeping an eye on biodiesel from microalgae, especially in the face of increasing energy demands and dependency on non-renewable fossil fuels. For example, the U.S. Department of Energy’s Aquatic Species Program reported in 1998 that biodiesel could be the only viable method to produce enough fuel to replace the world’s current diesel usage.
Algae in particular is an attractive source to achieve this, as compared to other biofuel crops, such as palm oil, soybeans or rapeseed oil, it is much easier to cultivate and more efficient as a fuel source. Additionally, studies have stated that to replace the global annual conventional diesel production of 1.1 billion tons, only 57.3 million hectares of algae would be required - which is much less than would be the case with other biofuel crops. Furthermore, algae can also be grown in lakes and ponds, reducing the competition on land with traditional agriculture.
Just How Dirty is Diesel?
The comparative cleanliness of diesel compared to gasoline has engendered much debate amongst the engineer and political communities. Traditionally, diesel vehicles are seen as being much cleaner than petroleum powered ones, resulting in many countries - particularly in Europe - pushing for their adoption and subsidising diesel fuel.
The reality is slightly more complex. For example, diesel actually requires more crude oil per gallon to produce and burning diesel can result in as much as 15 percent more greenhouse gas emissions than with petroleum. However, since diesel is a more efficient energy source, the amount of greenhouse gas emitted per mile is less. Diesel engines are also typically more modern and efficient than older gas-guzzlers, although they do require more energy to produce.
Additionally, diesel engines are worse polluters in regards to particulates and nitrogen oxides, which can result in smog and health complications for those who breathe them in. This resulting soot, termed ‘black carbon’, has also been linked to climate change by some.
Generally, however, governments have been more concerned with reducing their overall greenhouse gas emissions, than tackling particulate pollutants, resulting in diesel becoming an attractive alternative to gasoline. Despite this, several nations such as Germany, Ireland, India and the Netherlands have vowed to ban new diesel and petroleum powered vehicles by 2030.
The advantage of diesel, however, is that it can be turned into biodiesel resulting in much reduced emissions. Furthermore, although diesel is used for other functions, there are often alternatives in place to replace them - if still in their infancy. Previously, we have covered modern ship sails than can reduce the international shipping trade’s dependency on diesel, as well as floating solar panels that could replace diesel-fired generators on remote islands.