Scientists at the University of Leeds are turning low-grade sludge into high-value gas in a process which could make eco-friendly biodiesel even greener and more economical to produce.
Biodiesel – motor fuel derived from vegetable oil - is a renewable alternative to rapidly depleting fossil fuels. It is biodegradable and non-toxic, and production is on the up. But for each molecule of biodiesel produced, another of low-value crude glycerol is generated, and its disposal presents a growing economic and environmental problem.
Now researchers Leeds have shown how glycerol can be converted to produce a hydrogen rich gas. Hydrogen is in great demand for use in fertilisers, chemical plants and food production.
Moreover, hydrogen is itself viewed as a future ‘clean’ replacement for hydrocarbon-based transport fuels, and most countries currently reliant on these fuels are investing heavily in hydrogen development programmes.
The novel process developed by Dr Valerie Dupont and her co-investigators in the University's Faculty of Engineering mixes glycerol with steam at a controlled temperature and pressure, separating the waste product into hydrogen, water and carbon dioxide, with no residues. A special absorbent material filters out the carbon dioxide, which leaves a much purer product.
“Hydrogen has been identified as a key future fuel for low carbon energy systems such as power generation in fuel cells and as a transport fuel. Current production methods are expensive and unsustainable, using either increasingly scarce fossil fuel sources such as natural gas, or other less efficient methods such as water electrolysis.”
“Our process is a clean, renewable alternative to conventional methods. It produces something with high value from a low grade by-product for which there are few economical upgrading mechanisms” says Dr Dupont. “In addition, it’s a near ‘carbon-neutral’ process, since the CO2 generated is not derived from the use of fossil fuels.”
Dr Dupont believes the process is easily scalable to industrial production, and, as the race towards the ‘hydrogen economy’ accelerates, could potentially be an economically important, sustainable – and environmentally friendly – way of meeting the growing demand for hydrogen.
Dr Dupont’s research has been funded with a £270k grant from the Engineering and Physical Sciences Research Council (EPSRC) under the Energy programme, and is in collaboration with Professors Yulong Ding and Mojtaba Ghadiri from the Institute of Particle Science and Engineering, and Professor Paul Williams from the Energy and Resources Research Institute at the University. Industrial collaborators are Johnson Matthey and D1-Oils.
A ‘hydrogen economy’, reliant on hydrogen fuelling fuel cells and producing electrical power, instead of the low energy efficient internal combustion engines,is proposed to solve the ill effects of using hydrocarbon fuels in transportation, and other end-use applications, which causes the emission of greenhouse gases and other pollutants into the atmosphere. Whilst it’s likely to be many years before a full hydrogen economy can be achieved due to infrastructure and storage issues, biodiesel is a forerunner to this as a sustainable, more environmentally friendly fuel, to be used in combustion engines.
Hydrogen production is a large and growing industry. Globally, some 50 million metric tons of hydrogen, equal to about 170 million tons of oil equivalent, were produced in 2004. The growth rate is around 10 per cent per year. In the United States, 2004 production was about 11 million metric tons (MMT), an average power flow of 48 gigawatts. For comparison, the average electric production in 2003 was some 442 gigawatts. As of 2005, the economic value of all hydrogen produced worldwide is about $135 billion per year.
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