Image: This image shows a tubular glass photobioreactor for the cultivation of microalgae and other photosynthetic organisms. Credit: IGV Biotech (CC-BY SA 3.0).
Since it has become clear that ethanol and biodiesel made from food crops are doing more harm than good, the hope for finding a substitute for oil has shifted to algae and cellulose. If we can believe the advocates of this ‘second generation’ of biofuels, these combustibles will deliver way more energy than it takes to make them, without threatening the world’s food and water supplies. Upon taking a closer look, however, this is very hard to believe. They might even cause bigger problems than biofuels made from food crops. Maybe this time around we could sort this out before the damage gets done?
The biofuel disaster
Just two years ago, ethanol and biodiesel were heralded by almost everybody as a green substitute for oil. Today, almost everybody realizes that it is a foolish idea. Several studies have confirmed by now that it takes as much or even more energy to produce biofuels than they can deliver themselves.
That’s because the crops have to be planted, fertilized, harvested, transported, and converted into fuel, all processes that require fossil energy. If one also takes into account the land that is cleared to plant the energy crops, biofuels have become an extra source of greenhouse gases, while they were meant to lower them. Biofuels also helped to fuel a rise in food prices by competing for agricultural land. And very recently it also became clear that their production poisons water bodies.
In spite of this horrible record, both the European Union and the United States keep encouraging ethanol and biodiesel, mainly with the excuse that there is a ‘second generation’ of green fuels on the way, particularly cellulosic ethanol and algal fuel, which have no harmful effects. Sadly, this promises to be another dangerous illusion.
Cellulosic ethanol disaster
It is too early to say whether or not cellulosic ethanol can ever be produced with a net energy gain as a result – at the moment, it is impossible. We can only hope that scientists will never succeed, because what we do know for sure is that cellulosic ethanol will be an even larger threat to the world’s food supply than the first generation of biofuels.
Cellulosic ethanol is not made from the edible parts of crops, but from their stalks, roots and leaves. It can also be made of non-edible plants, like switchgrass. Therefore, at first sight, it seems unlikely that turning cellulose into fuel could present a danger for agriculture. However, there is one, literally invisible problem: the soil.
In nature, the concept of waste does not exist. The so-called “waste” that we plan to transform into fuel, is an essential element to keep the soil productive. Leaves, twigs and stalks are decomposed by underground organisms, which turn it into humus that can feed a next generation of plants.
If you take away this material, the soil will become less and less fertile until all you are left with is a desert. Of course, this process can be offset by adding more and more artificial fertilizers. But, here’s the rub: fertilizers are made from fossil fuels. Almost 30 percent of energy use in agriculture is attributed to fertilizer production (both their production process and their content). This means that the more energy we produce from cellulose, the more energy we will need to keep the soil fertile. In short: this makes no sense.
The first generation of biofuels might endanger the world’s food supply, but that process is reversible. We can decide at any moment to change our minds and use the corn to make food instead of fuel. A similar deployment of cellulosic fuels would destroy our agricultural soils, without any chance to repair them afterwards. We will have mined the soil – a process that is irreversible, because when the soil becomes too exhausted, even fertilizers are of no help. Cellulosic ethanol is a dangerous illusion. And if you don’t believe me, ask any soil scientist.
Nevertheless, as was announced earlier this week, the first cellulosic ethanol plant is scheduled to start working in 2009 (even despite the fact that scientists agree that a net energy gain is not yet possible).
The algae fuel disaster
Also earlier this week, the first algal fuel production facility went online and that generated lots of excitement. If we can believe the hype, it will not take long before we drive our cars and fly our planes on fuel made by algae. The figures sound impressive. Algae are expected to be able to produce 10,000 gallons of fuel per acre per year (some say 20,000 gallons), compared to 700 gallons for palm oil and less than 100 gallons for corn and soy.
Algae could also be used as a jet fuel and as a source to make plastics and detergents. Moreover, all this can be done with nothing more than sunlight and CO2 – and without the need for any potable water. If algal fuel plants are placed next to fossil fuel plants, as some companies are planning to do, the algae could even capture the CO2 from the emissions of the coal or gas plant. As one ecogeek summarized; “Welcome to the future, where single-celled plants eat our pollution and power our cars.”
There are very detailed figures on the amount of energy that will come out of the process, yet it is very hard to find any information on the energy and resources needed to make this energy output possible.
This sounds too good to be true. If you take a closer look at the claims of these companies, essential information seems to be missing. They present very detailed figures on the amount of energy that will come out of the process, yet it is very hard if not impossible to find any information on the energy and resources needed to make this energy output possible.
If algae don’t produce more energy than it takes to produce them, driving cars on algal fuel does not make much sense. And if they also use resources that are needed by agriculture, the game might not be worth the candle. These are important questions, as we have learned from the ethanol and biodiesel fiasco, yet nobody seems to wait for the answers.
Water in the desert
Algae have higher photosynthetic efficiencies than most plants, and they grow much faster. Up to 50 percent of their body weight is oil, compared to about 20 percent for oil-palm trees. They don’t need fertile ground, so that they can be grown on soil that is not suitable for agriculture.
All this sounds very good, but algae also need a few things, most notably: a lot of sunshine and massive amounts of water. To grow algae, you also need phosphorus (besides other minerals), an element that is very much needed by agriculture.
Most algae are grown in brackish or salt water. That sounds as if water is no issue, since our planet has not a shortage of salt water. However, just like solar energy plants, algae plants are best located in very sunny regions, like deserts. But, in deserts, and in very sunny places in general, there is not much water to find. That’s not a problem for solar plants, because they don’t need it. But, how are you going to get seawater to your desert algae plant? Check the websites of all these companies: not a word about it.
There are not that many possibilities. You can transport seawater to the desert, but that’s going to cost you an awful lot of energy, probably more than what can be produced by the algae. You can also take freshwater from more nearby regions or underground aquifers and turn it into artificial seawater. But, you promised that algal fuel would not compete with food production. A third option is to put your algae plant next to the sea.
Algae need a lot of sunshine and huge amounts of water - how do you get seawater to the desert?
Now, there are places which are both close to the sea and have lots of sun. But chances are slim that they are as cheap and abandoned like deserts are. Most likely, they are already filled up with tourists and hotels, to name one possibility. So you might be forced to look for a less sunny place close to the sea – which inevitably means that your energy efficiency is going down. Which again raises the question: will the algae deliver more fuel than is needed to make them?
How much water does algae production need? This information is nowhere to find. “A lot” would be a good bet for an answer, since it’s not enough to fill up the ponds or tanks just once. The water has to be supplemented regularly. Being able to produce 10,000 gallons of fuel per acre per year might sound impressive, but what really counts is how many gallons of fuel you can produce with a certain amount of water.
The water issue is not the only “detail” that threatens the energy efficiency of algal fuel. Compared to other plants, the photosynthetic efficiency of algae is high – almost 3 times that of sugar cane for instance. Compared to solar energy, however, the energy efficiency of algae is very low – around 1 percent, while solar panels have an efficiency of at least 10 percent, and solar thermal gets 20 percent and more.
So why would we choose algae over solar energy? One reason might be that it takes quite some energy to produce solar panels, while algae can be grown in an open shallow pond with nothing else but sunshine and CO2, which the organisms take from the atmosphere. You will still need energy to turn the algae into a liquid fuel, but other than that no energy input is needed.
However, these low-tech methods (comparable to growing corn, soy or palm trees to make ethanol or biodiesel) are being left behind for more efficient ones, using closed glass or polycarbonate bioreactors and an array of high-tech equipment to keep the algae in optimal conditions.
Even though some companies still prefer open ponds (like the PetroSun plant that started production last week), this method has serious drawbacks. The main problem is contamination by other kinds of algae and organisms, which can replace the energy producing algae in no time. Ponds also need a lot of space, because sunlight only penetrates the upper layers of a water body. It’s the surface of the pond that counts, not the depth.
The laws of physics
Transparent aquariums (called closed bio-reactors) solve all the problems of open ponds. These bioreactors can be placed inclined or suspended from the roof of a greenhouse so that they can catch more sun on a given surface. And since they are closed, no other organisms can enter. However, this method introduces a host of other issues. Bioreactors have a higher efficiency, but they also use considerably more energy.
First of all, you have to build an array of structures: the glass or polycarbonate containers themselves, the metal frames, the greenhouses. The production of all this equipment might consume less energy (and money) per square meter than the production of solar panels, but you need much more of it because algae are less efficient than solar plants.
Moreover, in closed bioreactors, CO2 has to be added artificially. This is done by bubbling air through the water by means of gas pumps, a process that needs energy. Furthermore, the containers have to be emptied and cleaned regularly, they have to be sterilized, the water has to be kept at a certain temperature, and minerals have to be added continuously (because also here, just as with cellulosic ethanol, “waste” materials are being removed). All these processes demand extra energy.
Are algal fuel producers taking these factors into account when they claim efficiencies that are 100 times higher than the ones from biodiesel and ethanol? Only they know. It could be that these businesses are greatly overestimating their energy gains in order to attract capital.
One of the few critics of algal fuel, Krassen Dimitrov, calculated that the figures of GreenFuel Technologies are defying the laws of physics. The company says that he is wrong, but his calculations surely look more convincing than the virtually non-existant information on their website (update May 2009: GreenFuel Technologies shuts down).
Feeding algae from smokestacks
Several companies plan to hook up their production facilities to a fossil fuel energy plant, in order to capture the CO2 and nitrogen emissions and “feed” them to the algae. This method is hailed as a way of reducing greenhouse gases emitted by coal and gas plants, which is a ridiculous claim. It’s very curious that this capturing technology is criticized when used in the context of “clean” coal, but applauded when it is used to make algal fuel. In both cases, capturing CO2 from smokestacks raises the energy use of the power plant by at least 20 percent.
It’s curious that capturing CO2 from power plants is criticized when used in the context of ‘clean’ coal, but applauded when it is used to make algal fuel.
That not only makes the technology very expensive, it also means that more coal or gas has to be mined, transported and burned. Algal fuel can even be considered a worse idea than “clean” coal. In the “clean” coal strategy, at least the CO2 is captured with the intention to store it underground.
In the case of algae, the CO2 is captured only with the intention to release in the air some time later, by a car engine. Last but not least, capturing CO2 from power plants ties algal fuel production to fossil fuels. If we switch to solar energy, where will the algal fuel producers get their CO2 from?
Outsourcing energy use
Are algae producers considering the extra use of energy that arises by the capture of the CO2 when they claim that algae can deliver 100 times more energy than first generation biofuels? This seems very doubtful. All these claims have one thing in common: they focus only on a small part of the total energy conversion chain.
A very good example is the story of Solazyme, a company that cultivates (genetically modified) algae in non-transparent steel containers, similar to those of breweries. In this case the algae do not get their energy from the sun, but from sugar that is fed to them. This method, says the company, makes them produce 1,000 times more oil than they do in sunlight, because sugar is a much more concentrated form of energy than sunlight.
But, where does the sugar come from? The researchers simply leave that part of the process out of their calculation, and nobody seems to care. Growing sugar cane of course requires significant amounts of energy, land and water.
In fact, by turning off photosynthesis, the researchers eliminate the only advantage of algae compared to other plants: their higher energetic efficiency. The photosynthetic efficiency of sugar cane is not even half that of algae, which means that if the whole energy chain would be considered, this process can only be worse than that of algae produced in transparent bioreactors.
Stop this madness
While the first generation of biofuels is wreaking havoc on the environment and the food markets, the second generation is getting ready to make things only worse. Behind the scenes, scientists are already working on the third generation, whatever that may be.
In five or ten years time, when it becomes clear that algal fuel is devouring our water and energy resources and cellulosic ethanol is mining our agricultural soils, we will be promised that the third generation will again solve all the problems of the previous generation.
Producing fuels out of food crops could be a useful and sustainable solution if our energy consumption would not be so ridiculously high
It might be a better solution to bury the whole idea of biofuels right here and now and focus on real solutions. The trouble with biofuels is not the technology, but our unrealistic expectations. Producing fuels out of food crops could be a useful and sustainable solution if our energy consumption would not be so ridiculously high.
All our habits, machines and toys are built upon an extremely concentrated form of energy, fossil oil, and trying to replace that fuel with a much less concentrated form is simply impossible. In 2003, Jeffrey Dukes calculated that 90 tons of prehistoric plants and algae were needed to build up one gallon of gasoline. We burn this amount of organic material to drive 25 miles to pick up some groceries.
In one year, the world burns up 400 years of prehistoric plant and algae material. How can we ever expect to fulfill even a small part of our fuel needs by counting on present plant and algae material? The problem we have to fix is our energy consumption. Biofuels, from whatever generation, only distract us from what really should be done.
Scientists warn of lack of vital phosphorus as biofuels raise demand (June 2008).
How much energy does it take to construct algal factories? Chris Rhodes from Energy Balance made an eye-opening calculation (November 2008).
The water footprint of bioenergy (April 2009): barley, cassava, maize, potato, rapeseed, rice, rye, sorghum, soybean, sugar beet, sugar cane, wheat and jatropha. Algal fuel is not included, but the results are significant. It takes 1,400 to 20,000 litres of water to produce 1 litre of biofuel.
Amid a sea of troubles, ethanol now has an antibiotics problem (April 2009).
GreenFuel Technologies shuts down. (May 2009)