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Tina Casey headshot

Tiny Microalgae Could Lead Hydrogen Economy

By Tina Casey

Despite skepticism from some quarters, it appears the hydrogen economy is beginning to take shape with accelerating speed. In the latest news, a research team at Tel Aviv University developed a way to speed up the rate of algal hydrogen production by about 400 percent.

The news is significant because it provides another pathway for producing hydrogen from renewable sources that are far more sustainable than the current source of choice, natural gas.

The path to renewable hydrogen

From a tailpipe perspective, hydrogen is an attractive fuel because it produces no emissions when used in a fuel cell. Fuel cells generate electricity by combining hydrogen with oxygen, and the only byproduct is water.

In a fuel cell microgrid, that water can be collected and reclaimed for use, adding another layer of sustainability to the system.

The picture is completely different from a supply chain perspective, because the main source of hydrogen today is natural gas. That supply chain drags an enormous burden including global warming emissions all along the drilling, transportation and storage system.

Local impacts related to fracking and fracking wastewater disposal are another major concern.

On the plus side, researchers are beginning to develop alternative systems for producing hydrogen.

One type of system that's getting a lot of attention is water-splitting, in which solar power or wind power are deployed to separate hydrogen from water.

Initial attempts at water-splitting relied on the use of clean, treated water. In the latest crop of water-splitting systems there are examples of deploying renewable energy to produce hydrogen from polluted water. The result is an environmental twofer, because the hydrogen production system also removes pollutants from the water.

The microalgae pathway

Another pathway is based on biomass, and that's where the new Tel Aviv University (TAU) research comes in.

The story goes back to 2011, when TAU professor Iftach Yacoby was a postdoc researcher at MIT. He was a member of a research team that found a way to "flip" the preferences that microalgae have for producing various compounds.

Scientists have known for decades that cyanobacteria and other microalgae produce tiny amounts of hydrogen. However, their systems are normally geared toward producing sugar, which they need as a nutrient. Hydrogen is just a byproduct.

To upend that preference, the MIT team introduced a "multitasking" enzyme into the microalgae. The enzyme is capable of driving two changes at once. It tamps down sugar production, and it "redirects" more energy into hydrogen production.

The MIT work was the first demonstration that sugar and hydrogen production could be manipuated together, in a laboratory setting.

It was also a real breakthrough because previously, researchers thought that microalgae produce hydrogen only under limited conditions, for a few minutes each day. The MIT research demonstrated that it takes place continuously, though in very small amounts.

This stage of the research resulted in a 400 percent increase in hydrogen production.

Dr. Yacoby is now the head of his own lab at TAU, where his team is working on synthetic enzymes capable of industry-scale production.

It's complicated ...

The enzyme approach sounds simple enough, but a look into the mechanics of the operation reveal why that industrial-scale solution has not yet leaped from the laboratory into an industrial park near you.

Basically, what the TAU team is trying to do is to leverage the energy of photosynthesis. If you think of that energy in terms of electrons, the picture becomes clear.

Normally, microalgae absorb electrons from solar energy and "shuttle" most of them toward producing food to fuel their own growth. Diverting those electrons is the key to the whole thing, and the TAU team has identified two main challenges.

First, the enzyme in question -- hydrogenase -- is sensitive to oxygen. If exposed to air, it becomes inactive within five seconds. The TAU team has been engineering mechanisms that remove oxygen.

Second, the ratio of electron diversion for other processes is rather high. The TAU team recently completed analyses that put the ratio at 85 percent. The challenge moving forward is to lower the diversion rate while still providing the organism's other systems with enough electrons to keep it functioning.

If the research continues to progress, brace yourself for the hydrogen "revolution" envisioned by Dr. Yacoby:

"Since the beginning of time, we have been using agriculture to make our own food. But when it comes to energy, we are still hunter-gatherers. Cultivating energy from agriculture is really the next revolution."

The research is a lot closer than it was five years ago, so stay tuned. The team just published two studies, in the journals Plant Physiology and Biotechnology for Biofuels, that propose a pathway for ramping up mass production.

Image (screenshot): via TAU.

Tina Casey headshot

Tina writes frequently for TriplePundit and other websites, with a focus on military, government and corporate sustainability, clean tech research and emerging energy technologies. She is a former Deputy Director of Public Affairs of the New York City Department of Environmental Protection, and author of books and articles on recycling and other conservation themes.

Read more stories by Tina Casey