Some weeks ago I wrote two posts titled: “The Potential of Bio-based Plastics” (part 1 and part 2) in which I reviewed a study regarding the potential of bio-based plastics. The study meanly concentrated on feed stock which need more or less large quantities of arable areas which could and should, in my opinion exclusively, be used for food and not for bio-fuels or bio-based plastics. At the same time the Amazon Rain Forest and the Cerrado Savannah are cut down to create space for planting soy with the final goal to extract bio-fuel. (Read my article: “The Cerrado Suffers Worse Than The Amazon.”)
So my hope went up when some weeks ago California-based Cereplast announced the manufacturing of plastics from algae. Unfortunately, but not surprisingly and although of significant importance the press release didn’t get the attention in the (professional) media that it deserved. Why? I think algae are not glamorous and everybody thinks it’s a far away technology. A wishful thinking. But is it?
Let’s have a look at Cereplast’s press release first:
Cereplast, Inc., manufacturer of proprietary bio-based sustainable plastics, announced that it has been developing a breakthrough technology to transform algae into bio-plastics and intends to launch a new family of algae-based resins that will complement the company’s existing line of Compostables and Hybrid resins.
Cereplast algae-based resins could replace 50% or more of the petroleum content used in traditional plastic resins. Currently, Cereplast is using renewable material such as starches from corn, tapioca, wheat and potatoes.
Cereplast is still in the development phase, but believes that this breakthrough technology could result in a significant new line of business in the years to come.
Frederic Scheer, Founder of Cereplast, believes that algae has the potential to become one of the most important “green” feedstocks for bio-fuels, as well as bio-plastics.
Clearly, his and my focus are on bio-plastics. Algae as biomass make sense as it helps close the loop on polluting gases and can be a significant renewable resource.
As we all know, the majority of plastics fall into the category of fossil plastics, which are non-energy products of the petroleum chemicals. Petroleum-based plastics are considered to be non-biodegradable, or at best only slowly biodegradable. This, coupled with the amount of plastics produced and ending up as litter or in landfills, is primarily responsible for the activity towards plastics that are biodegradable. Municipal solid waste contains 7% by weight and 17-25% by volume of plastics, largely from packing materials.
Replacement of petro-chemically based plastics by biologically derived plastics would reduce petroleum usage. Litter from such plastics would disappear into its surroundings to leave only normal biological residues. Unfortunately the industry is concentrating on using renewable material grown on arable lands that should be used for food.
The algal plastics and algal plastic precursors are made from filamentous green algae – pond scum, kelp, seaweed, and the like – a huge family of more than 30,000 organisms that photosynthesize sunlight but lack roots, shoots, and leaves — grows quickly, with some species nearly doubling in volume overnight. Almost half the body weight of some species are lipids, the scientific term for oil. There’s evidence that humans have used algae for millennia: Chinese texts from 5,000 BC mention it, Irish farmers once fed it to their cattle and think in terms of the wrapped sushi.
When researching this subject, you find that an acre of algae can possibly produce 100,000 gallons of fuel in a year — or maybe it’s 30,000 gallons or 4,000 gallons or 400 gallons. Yet even the lowest figure, scientists say, compares favourably with the 50 gallons for an acre of soybeans, canola’s about 160 gallons per acre per year, and palm’s about 600 gallons per acre per year. But some types of algae can produce at least 2,000 gallons of oil per acre per year.. (Note: ratio acre : hectare = approx. 2½; an US gallon = 3.786 litres).
Growing algae artificially can be a challenge. Too much light or too little, too hot or too cold and algae stop producing. And the list goes on. Various companies have come up with ingenious solutions to these problems. Although algae live in water, land-based methods are used to grow algae. Two land-based methods used today are open ponds and closed bioreactors.
Open ponds are shallow channels filled with freshwater or seawater, depending on the kind of algae that’s grown. The water is circulated with paddle wheels to keep the algae suspended and the pond aerated. They are inexpensive to build and work well to grow algae, but have the inevitable problem of water evaporation. To prevent the ponds from drying out or becoming too salty, conditions that kill the algae, an endless supply of freshwater is needed to replenish the evaporating water.
When closed bioreactors are used to grow algae, water evaporation is no longer the biggest problem for algae’s mass-production. Bioreactors, enclosed hardware systems made of clear plastic or glass, present their own problems. They can be computer-controlled and monitored around the clock for a more bountiful supply of algae. However, storing water on land and controlling its temperature are the big problems, making them prohibitively expensive to build and operate. In addition, both systems require a lot of land.
Remarkable, and almost creating a perfect loop, is NASA’s plan for algae harvesting in the ocean. Large plastic bags filled with sewage would be placed in the ocean to grow algae. These bags have semi-permeable membranes that will provide home for algae to grow (using up sewage for this purpose) and will allow fresh water to flow out, thus not getting encumbered by evaporation and refill issues that plague closed bioreactors. Furthermore it does not compete with agriculture for land or freshwater.
The bag will be made of semi-permeable membranes that allow fresh water to flow out into the ocean, while retaining the algae and nutrients. The membranes are called “forward-osmosis membranes.” They are normal membranes that allow the water to run one way. With salt water on the outside and fresh water on the inside, the membrane prevents the salt from diluting the fresh water. It’s a natural process, where large amounts of fresh water flow into the sea.
Floating on the ocean’s surface, the inexpensive plastic bags will be collecting solar energy as the algae inside produce oxygen by photosynthesis. The algae will feed on the nutrients in the sewage, growing rich, fatty cells. Through osmosis, the bag will absorb carbon dioxide from the air, and release oxygen and fresh water. The temperature will be controlled by the heat capacity of the ocean, and the ocean’s waves will keep the system mixed and active.
When the process is completed, bio-fuels and bio-based plastics will be made and sewage will be processed. For the first time, harmful sewage will no longer be dumped into the ocean. The algae and nutrients will be contained and collected in a bag. Not only will oil be produced, but nutrients will no longer be lost to the sea. According to NASA, the system is fail proof. Even if the bag leaks, it won’t contaminate the local environment. The enclosed fresh water algae will die in the ocean.
With a bit of luck and some billions in research and development we might have algal-based plastics on a large scale in some 5 years, without using arable land.