What is Algae Anyway?
There are a lot of different types of algae, from the large kelp forests in our oceans (macroalgae) to the hundreds to thousands of single-celled organisms that can be in a droplet of lake water (microalgae). Microalgae, or what we call phytoplankton, are simply a large group of aquatic, photosynthesizing organisms that are shuttled around by the currents and movement of the water they live in. They typically cannot be seen with the "naked eye" but when conditions are just right, "blooms" of algae can take place that can be seen from space! Algae require a number of things to survive, mainly nitrogen, phosphorus, sunlight (solar energy), and carbon dioxide. Since algae are extremely small, their surroundings can greatly influence them. The water temperature and access to light greatly impacts the rate at which algae "grow" or reproduce. Algae compete with the algae that surround them, pitted in a battle to take up all of the necessary nutrients they require, and at time taking up more than they need to store for later uses. Algae also face a fierce predator in the zooplankton.
Microalgae make up the base of aquatic food webs, the "primary producers." If you take a deep breath, over 50% of that breath can be attributed to the microalgae that live in our streams, ponds, lakes and oceans (Take that Amazon Rainforest!). Needless to say, these little guys are extremely important for all of life on Earth. But now algae is emerging as an even more important player, an extremely promising alternative energy source! From algae we can take out the sugar and starches inside the cells and ferment them to produce ethanol. The fats, aka lipids, within the cells can be converted into diesel fuel. And all the leftovers can be digested anaerobically to produce methane.
There are a lot of different types of algae, from the large kelp forests in our oceans (macroalgae) to the hundreds to thousands of single-celled organisms that can be in a droplet of lake water (microalgae). Microalgae, or what we call phytoplankton, are simply a large group of aquatic, photosynthesizing organisms that are shuttled around by the currents and movement of the water they live in. They typically cannot be seen with the "naked eye" but when conditions are just right, "blooms" of algae can take place that can be seen from space! Algae require a number of things to survive, mainly nitrogen, phosphorus, sunlight (solar energy), and carbon dioxide. Since algae are extremely small, their surroundings can greatly influence them. The water temperature and access to light greatly impacts the rate at which algae "grow" or reproduce. Algae compete with the algae that surround them, pitted in a battle to take up all of the necessary nutrients they require, and at time taking up more than they need to store for later uses. Algae also face a fierce predator in the zooplankton.
Microalgae make up the base of aquatic food webs, the "primary producers." If you take a deep breath, over 50% of that breath can be attributed to the microalgae that live in our streams, ponds, lakes and oceans (Take that Amazon Rainforest!). Needless to say, these little guys are extremely important for all of life on Earth. But now algae is emerging as an even more important player, an extremely promising alternative energy source! From algae we can take out the sugar and starches inside the cells and ferment them to produce ethanol. The fats, aka lipids, within the cells can be converted into diesel fuel. And all the leftovers can be digested anaerobically to produce methane.
Into To Algal Biofuels The era of inexpensive fossil fuels is coming to a rapid end as global demand for energy is ever increasing. If this rate of consumption continues to grow at a conservative level of 3% annually, a recent report projects that fossil fuel resources will be completely depleted within the next 60-100 years, depending on how successful new energy reserve exploration is (Stephens et al., 2010). In addition to these resources being finite and rapidly being depleted, the environmental impacts of their combustion is beginning to be realized. Habitat destruction for mining and extraction has dramatic impacts on wildlife populations and the quality of other natural resources (water, air, etc.). The growing evidence for human-caused climate change is also a direct result from combusting these fossil fuel sources releasing an unprecedented amount of carbon dioxide (CO2) into the atmosphere. This increased level of CO2, a strong greenhouse gas, is leading to increased global temperatures, rising sea levels, and more frequent and violent storms. These findings demand that society begins to invest and develop alternative energy resources.
For these renewable resources to be realized they must:
1.) Be produced at an industrial scale to meet the increasing demand, 2.) Be produced efficiently to maintain low energy costs for the consumers 3.) Not take land from the global food system 4.) Be environmentally sustainable. |
Algae are extremely promising as a biofuel source because:
1.) They rapidly reproduce (highly productive) 2.) Require limited amounts of nutrients and have a high energy content 3.) Require very limited amounts of land compared to other biofuel options 4.) The algae life cycle from "cradle to combustion" can be carbon-neutral |
Growing Algae @ the Industrial Scale There are two main techniques employed to mass cultivate algae.
1.) Open, outdoor raceway ponds - Simply a body of water that is about 30cm in depth and is shaped like a racetrack. The algae is moved through the raceway with a slow rotating paddle wheel that maintains enough mixing to get algae the necessary sunlight and prevents them from settling to the bottom. These systems can suffer from invasion by unwanted algae, predators, and pathogens (like fungi). They also are exposed to the changing environmental conditions (temperature, light, pH, etc.)
2.) Closed Photobioreactors (PBRs) - Closed PBRs are sealed systems that can maintain sterile cultures of algae without contamination of unwanted algae, predators or pathogens. But they are much more expensive than the raceway ponds. They also can heat the water within to extreme temperatures, and even have such high levels of oxygen that it can become poisonous to the algae.
1.) Open, outdoor raceway ponds - Simply a body of water that is about 30cm in depth and is shaped like a racetrack. The algae is moved through the raceway with a slow rotating paddle wheel that maintains enough mixing to get algae the necessary sunlight and prevents them from settling to the bottom. These systems can suffer from invasion by unwanted algae, predators, and pathogens (like fungi). They also are exposed to the changing environmental conditions (temperature, light, pH, etc.)
2.) Closed Photobioreactors (PBRs) - Closed PBRs are sealed systems that can maintain sterile cultures of algae without contamination of unwanted algae, predators or pathogens. But they are much more expensive than the raceway ponds. They also can heat the water within to extreme temperatures, and even have such high levels of oxygen that it can become poisonous to the algae.
Algae to Biofuel Algae naturally produce these fats, or lipids, within their cells that are used for a number of functions for their everyday life. Some lipids are designated to produce or replenish the membrane that encapsulates the internal organs of the cell. Some lipids are produced and stored away as an insurance policy for harsh times in ahead. These storage lipids are what make algae so promising as a biofuel source. These lipids are made up of fatty acids that are a perfect precursor for diesel fuel. Different species of algae produce different amounts of storage lipids, and identifying species that produce larger quantities has been a large focus of previous research. Algal cells can also be "tricked" into producing more storage lipids than normal by stressing the cells out. Removing the nitrogen from the phytoplankton's environment begins to stress the cell, and the cells will begin investing in storing, hedging against future harsh conditions, instead of investing in reproduction. A wonderful research that I know, Dr. Maria Stockenreiter, was the first to show that as the number of algal species that are growing together increases so does the overall amount of lipids that are produced in the algal ponds! This "benefit of biodiversity" is a fundamental component of my personal research and is covered in more detail under the "Research" Tab.