Algae can be engineered to hyper-produce hydrogen, a clean source of energy for cars and industry, too, say Tel Aviv scientists
Ruth Schuster Sep 12, 2016

You could be growing your own car fuel in some scummy green tank in your living room one day, with or without engineered fluorescent fish inside. No, you wouldn’t be gassing the car or powering the house with fish pee, but with hydrogen produced by engineered algae.

Hydrogen is widely touted as the fuel of the future and now Tel Aviv University scientists have made two crucial discoveries. One is how algae produce it. The other is how to make them produce more of it, so hydrogen can be mass-produced, cheaply, and used not only in public transportation but industry.

“For the last 12,000 years we have been using agriculture to make food, but when it comes to energy, we are still hunter gatherers. Agriculture for energy is the next revolution,” research leader Assistant Prof. Iftach Yacoby, head of the renewable energy laboratory at Tel Aviv University, tells Haaretz. “There are other ways to produce hydrogen, but this is the greenest, and is the only agricultural one.”

In two separate papers published in the international science press, the TAU team describes the discovery that algae produce hydrogen from photosynthesis, not in a microburst at dawn, as assumed until now, but all the time. Secondly and crucially, they have engineered a way to boost production nearly fivefold by genetic engineering.

In case that all sounds rather like a thriller starring a shaven-headed tattooed ex-con clad in inexplicably-sourced leather and armed with a vial of glowing green goo, think of this. The wheat we know and love isn’t the plant we began to cultivate 12,000 years ago. We changed it to enhance desirable traits. Doing the same to microalgae is next. If hydrogen-by-alga can be developed industrially, modern civilization could finally start getting over its addiction to oil, with all the geopolitical relief that would entail.

Making hydrogen all day long

Photosynthesis is a biochemical process by which competent plants, algae and bacteria convert light energy into chemical energy. Generally speaking, photoautotrophs start from carbon dioxide (CO2) and water (H20) that they first split into the composite atoms, carbon, oxygen and protons, using sunlight energy, then “cook” to make glucose sugar (‎C6H12O6).

When making sugar by photosynthesis, plants output some oxygen, chiefly during the day. The scientists worked with single-celled green algae and first of all discovered that in contrast to popular wisdom, algae produce hydrogen during the photosynthetic process all day, not in a brief burp at sunrise.

How could they be so wrong so long? A) “Because the amounts of hydrogen the algae produce at other times were miniscule,” Yacoby explains. “Highly sensitive machinery was necessary to discern it.” B) Also, the scientists had known that oxygen is deadly to a key stage in the algal hydrogen production process, which led them to a wrong assumption.

Oxygen stifles the relevant enzymes, called hydrogenases. They stop working, irreversibly, and scientists had assumed that the enzyme was simply not active in air-grown algae cells.

Actually, they discovered, the enzyme remains frisky and active inside oxygen-free zones inside the chloroplast (which is the organelle that contains the chlorophyll, the molecule central to photosynthesis). And thus the little alga continues to make hydrogen all day long.
Single-celled algae produce hydrogen all day, not in one dawn microburst, it turns out.TAU

More of a good thing

The next question was how to beef up production for industrial purposes. We clearly don’t need to engineer totally new hydrogenases that aren’t oxygen-sensitive, Yacoby explains to Haaretz.

What humanity needs is to get the algae to overproduce the enzyme and, as he explains, to reengineer it to have more power.

Currently most of the energy goes to sugar production, he explains. That is what the plant wants. We however would like most of the energy to be transferred to hydrogen production.

Why go through the trouble of engineering single-celled plants? Man knows how to produce hydrogen, doesn’t he?

He does, but not cleanly, Yacoby explains. “In the United States, 99% of the hydrogen produced is from natural gas.” Cracking natural gas for hydrogen is not a green process, is toxic as hell and is energetically inefficient. Producing hydrogen through electrolysis requires electricity – which is not always available from green sources.”

Biofuels are hardly the great white hope either. For one thing, when they’re burned (i.e., used,) we get carbon emissions. With hydrogen, the only emission is water vapor.

“Making ammonia for fertilizer so we can grow more corn so we can make more ethanol to fuel cars that pollute – this is not the most efficient practice one can perceive,” Yacoby remarks. “Hydrogen is the only blue energy – no carbon emission from the exhaust.”

He also points out that a hydrogen-powered car, and they exist commercially nowadays thanks to Toyota and now other car manufacturers, can run more than 500 kilometers on five kilos of hydrogen.

What about cost? Bioengineered algae sound expensive. The scientists have done the math and, says Yacoby, the production costs should be less than $4 per kilo of hydrogen, which, mileage-wise, is roughly equivalent to 10 liters of gasoline. National Renewable Energy Lab in Colorado thinks hydrogen can be made using the algae method for around $3 per kilo.
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