Turning carbon dioxide emissions into chemicals, fibers and jet fuel

Turning carbon dioxide emissions into chemicals, fibres and jet fuel

A carbon revolution? Scientists are using the principles of photosynthesis to turn CO2 emissions into useful products

Shell is collaborating on a project in Switzerland that will produce jet fuel, using carbon dioxide, water and solar energy. Photograph: Gerolf Kalt/ Gerolf Kalt/Corbis

Bernie Bulkin

Monday 4 August 2014 13.28 BST

When fuels are burned, the products are carbon dioxide, water, and heat. Lots of heat. This heat takes energy out of the chemicals (say petrol, coal or gas) and releases it, leaving behind very low energy molecules, like CO2. A chemist's dream is to find efficient ways of putting this energy back into the carbon dioxide to turn it into something else useful. In other words, to convert a waste product that causes global warming into something useful.

If carbon dioxide is in a product that will keep it locked up for a long period of time, like furniture or building insulation, this is a way of removing it from the air: carbon capture. And CO2 is free or, given policies to make the emission of carbon dioxide a cost to business, it even becomes a starting material for chemistry that has a negative cost.

Luckily, nature already does what chemists aspire to. It efficiently takes carbon dioxide from the air, using energy from sunlight and natural catalysts, and converts it into the carbon building blocks of plants and trees: photosynthesis. Given the intense international focus on greenhouse gases over the past decade, it is unsurprising that many chemists are trying to find routes to useful products. The challenge, as with much of chemistry, is to find synthetic catalysts that speed up reactions in a way that is as good as nature or better.

Liquid Light, a spinout from Princeton University, uses electricity and catalysts (what they are is a secret), to make chemicals from carbon dioxide, and seems to have progressed to having a near-commercial process to make ethylene glycol, a key component of anti-freeze and, more interestingly, a building block of polyester bottles and fibres. Scientists at Liquid Light believe they can tailor their catalysts to make other chemicals, and that the electricity used can come from solar panels. The company takes photosynthesis-level efficiency as the benchmark against which to measure their process, and claims it is now twice as efficient.

A German chemical company, BASF, and a US company, Novomer, are capturing CO2 from power plants or other waste sources, using novel catalysts to make polypropylene carbonate. This plastic can be used for coatings, adhesives, foams and packaging and can replace other plastics in these applications that are currently made from oil. Both companies are moving towards commercial processes. Bayer, another large German chemical company, is also advancing a process to make polyurethane foams using carbon dioxide.

A more brute force approach is that taken by the Solar Jet programme in Switzerland, led by Dr Aldo Steinfeld of ETH-Zurichcollaborating with Shell. They designed a clever reactor that generates very high temperatures from solar energy to break down carbon dioxide and water, converting them to hydrogen and carbon monoxide. From this mixture they can make kerosene for jet fuel using well-known chemical processes. This is still at an early stage – so far they have made one litre of fuel – but sometimes these high temperature processes are more straightforward to scale up than catalyst-based approaches.

Carbon dioxide utilisation is attracting clever chemists and engineers, start-up venture capital and big established players. This is an area to watch for one or more revolutions of the chemical industry in the next five years.

Turning carbon dioxide emissions into chemicals, fibers and jet fuel

6:12 PM alternate energy, co2 conversion, fuel

Artificial Leaf. Will it be the Energy source of the future ?

Artificial Leaf: the new ways of producing energy

At the very beginning of the human race, concurring the energy source was the ultimate target. And still we are racing behind a renewable, affordable energy source. We already witnessed wars and fight for capturing energy sources and witnessed the rise of economical power of the world  from scratch  just becuse of having the natural energy resources.

The world is and will be highly worried about the avaialbility of the natural resources. The depresiation of the resources is really an unforgatable thoughts. But still we are not able to come up with a replaceble source for natural resources. One advantage of liquid fuel is propotrion of stored energy in it  and storage space required.  To use elctric current insted of liquid fuel to fly a flight, just imagine the amount for batteries required to store the power. So the real though is to come up with a real alternate energy source  which is to be efficient, cheap and robust. And it is the ultimate challenge for the existance of the entire humnity.

In recent publication of Nature, discused about a concept of Artificial leaf. This leaf is just not a leaf made of synthetic material, the artifical part is the functionality of the leaf. Yes we are trying to mimic the function of a leaf 'the photosysnthesis'. Ultimately the energy source we are looking for the solar energy.

The concept of artificial photosynthesis goes back to 1912, but the push to achieve it did not start until 1972, when Japanese researchers outlined what a device would need to take in sunlight and use it to split water into oxygen and hydrogen fuel2. Progress was slow. In 1998, Turner reported3 a complete system that showed a major advance — it stored 12% of the incoming solar energy as fuel, compared with 1% of energy stored as biomass in real leaves. But it cost more than 25 times too much to be competitive, and its performance dropped off after 20 hours of sunshine.

In the process, to create a system that is much cheaper than just splitting water with electricity from a solar panel. At the heart of JCAP's artificial-leaf design are two electrodes immersed in an aqueous solution. Typically, each electrode is made of a semiconductor material chosen to capture light energy from a particular part of the solar spectrum, and coated with a catalyst that will help to generate hydrogen or oxygen at useful speeds (see 'Splitting water'). Like many other artificial-photosynthesis devices, JCAP's system is divided by a membrane to keep the resulting gases apart and reduce the risk of an explosive reaction.

Once the water has been split, the hydrogen is harvested. It can be used as a fuel by itself — perhaps in hydrogen-powered cars.

Making any one of the artificial leaf's components work well is a challenge; combining all of them into a complete system is even harder. Much of the difficulty comes down to finding the right materials. Silicon, for instance, makes a good photocathode — the electrode that produces hydrogen gas — but is stable only when the solution around it is acidic. Unfortunately, the situation is reversed with photoanodes, which produce oxygen: the good ones are stable only when the solution is basic, not acidic. And the best catalyst for the oxygen-producing electrode, iridium, is both rare and expensive, which makes it unsuitable for commercial-scale devices.

Light industry

Another entrant in the artificial-photosynthesis field is the Japan Technological Research Association of Artificial Photosynthetic Chemical Process (ARPChem), a consortium of universities and companies that has government funding comparable to JCAP's grant — although over ten years rather than five — to develop a bag-based approach. Kazunari Domen, a chemist at the University of Tokyo and leader of ARPChem's water-splitting group, says that one of the companies in the consortium has been working on a membrane to separate the hydrogen and oxygen products.
Other projects are making photoabsorbers from organic molecules, rather than semiconductors. Some are building molecular assemblies inspired directly by the photosynthetic apparatus of plants. And in the past few years, a class of materials called perovskites has drawn the attention of the solar-photovoltaic community for its high energy-conversion efficiency; some researchers think that the materials also have potential in artificial photosynthesis.
Daniel Nocera, a chemist at Harvard University in Cambridge, Massachusetts, launched Sun Catalytix to develop his work on a low-cost catalyst. But the company announced last year that it has put that research on hold to pursue a less challenging product with prospects of turning a profit for investors sooner. The decision underscores the challenges of bringing a commercially viable artificial-photosynthesis system to market.


 

Artificial Leaf. Will it be the Energy source of the future ?

9:47 PM Artificial leaf, energy, fuel, solar energy, splitting water