The leaves manufacture the needs of the plant by simply combining water sunlight and carbon dioxide through the miracle of photosynthesis. Now researchers mimics natures process to produce fuel and fertilizer by combining chemistry and biology in bionic leaf.
In the second half of the 20th century, the mass use of fertilizer was part of an agricultural boom called the “green revolution” that was largely credited with averting a global food crisis. Now, the challenge of feeding the world looms again as the population continues to balloon.
The first “green revolution” in the 1960s saw the increased use of fertilizer on new varieties of rice and wheat, which helped double agricultural production. Although the transformation resulted in some serious environmental damage, it potentially saved millions of lives, particularly in Asia, according to the United Nations (U.N.) Food and Agriculture Organization. But the world’s population continues to grow and is expected to swell by more than 2 billion people by 2050, with much of this growth occurring in some of the poorest countries, according to the U.N. Providing food for everyone will require a multi-pronged approach, but experts generally agree that one of the tactics will have to involve boosting crop yields to avoid clearing even more land for farming.
To contribute to the next green revolution, researchers from Harvard University, chemist Daniel Nocera and biologist Pamela Silver Nocera, develop bionic leaf that uses bacteria, sunlight, water and air to make fertilizer in the very soil where crops are grown. The bionic leaf is a device that, when exposed to sunlight, mimics a natural bacteria Ralstonia eutropha, which consumes hydrogen and takes carbon dioxide out of the air to make liquid fuel. This combination produces biomass and liquid fuel yields exceeding the natural process of photosynthesis.
To prove it, the researchers used their system to grow five crop cycles. The vegetables receiving the bionic-leaf-derived fertilizer weigh 150 percent more than the control crops. The next step, Nocera says, is to boost throughput so that one day, farmers in India or sub-Saharan Africa can produce their own fertilizer.
The research output is set to be presented at the 253rd National Meeting & Exposition of the American Chemical Society (ACS) this week, 2-6 April 2017, in San francisco California.
Sustainable solar-to-fuels and solar-to-fertilizer production
Hybrid inorganic | biological constructs have been created to use sunlight, air and water to accomplish carbon fixation and nitrogen fixation thus enabling distributed and renewable fuels and fertilizer generation. The carbon fixation cycle is achieved by interfacing the oxygen evolving and hydrogen evolving catalysts of the artificial leaf with an engineered bioorganism. Using the tools of synthetic biology, a bio-engineered bacterium has been developed to convert carbon dioxide, along with the hydrogen produced from the artificial leaf, into biomass and liquid fuels, thus closing an entire artificial photosynthetic cycle. This hybrid microbial | artificial leaf system scrubs 180 grams of CO2 from air, equivalent to 230,000 liters of air per 1 kWh of electricity. This hybrid device, called the bionic leaf, operates at unprecedented solar-to-biomass (10.7%) and solar-to-liquid fuels (6.2%) yields, greatly exceeding the 1% yield of natural photosynthesis. Extending our approach, we have discovered a renewable and distributed synthesis of ammonia at ambient conditions by coupling solar-based water splitting to a nitrogen fixing bioorganism in a single reactor. Nitrogen is fixed to ammonia by using the hydrogen from the artificial leaf to power a nitrogenase installed in the bioorganism. The ammonia produced by the nitrogenase can be diverted from biomass formation to an extracellular product with the addition of an inhibitor. The nitrogen reduction reaction proceeds at a low \ driving force (~ 0.16 V) with a turnover number (TON) of 8 × 109 per cell and operates at 15 to 23% of the theoretical yield without the use of any sacrificial chemical reagents and carbon feedstock (which is provided by CO2 from air). This approach can be powered by distributed renewable electricity, enabling the sustainable production of nitrogen fertilizer.
In the second half of the 20th century, an agricultural boom called the “green revolution” was largely credited with averting a global food crisis. Now, the problem of feeding the world’s growing population looms again. To help address the challenge, researchers present at the 253rd National Meeting & Exposition of the American Chemical Society a “bionic” leaf that uses bacteria, sunlight, water and air to make fertilizer in the very soil where crops are grown.