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Topic Name: Leeds researchers are turning low-grade sludge into ‘hydrogen economy’
Category: BioFuels
Research persons: Dr Valerie Dupont
Location: University of Leeds, United Kingdom
Details
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.
Hydrogen economy
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.
Note for Sludge
Sludge is the residual semi-solid material left from industrial, water treatment, or wastewater treatment processes.
When fresh sewage or wastewater is added to a settling tank, approximately 50% of the suspended solid matter will settle out in about an hour and a half. This collection of solids is known as raw sludge or primary solids and is said to be "fresh" before anaerobic processes become active. Once anaerobic bacteria take over, the sludge will become putrescent in a short time and must be removed from the sedimentation tank before this happens.
Note for Glycerol
Glycerol is a chemical compound with the formula HOCH2CH(OH)CH2OH. This colorless, odorless, viscous liquid is widely used in pharmaceutical formulations. Also commonly called glycerin or glycerine, it is a sugar alcohol, and is sweet-tasting and of low toxicity. Glycerol has three hydrophilic alcoholic hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. Its surface tension is 64.00 mN/m at 20 °C , and it has a temperature coefficient of -0.0598 mN/(m K). It is a central component of lipids.
In foods and beverages, glycerol serves as humectant, solvent and sweetener, and may help preserve foods. It is also used as filler in low-fat food products (i.e., cookies), and as a thickening agent in liqueurs. Glycerol is also used as a sugar substitute. In this regard, it has approximately 27 calories per teaspoon and is 60% as sweet as sucrose. Although it has about the same food energy as table sugar, it does not raise blood sugar levels, nor does it feed the bacteria that form plaques and cause dental cavities. As a food additive, glycerol is also known as E number E422.
In organic synthesis, glycerol is used as a readily available prochiral building block.
About Researcher
Dr Valerie Dupont is a senior lecturer in the Energy & Resources Research
Institute (ERRI) in the Faculty of Engineering. Her research interests span
combustion and fuel engineering, fuel science and technology, by-products
relating to fuels, the chemistry of catalysis and energy and the environment.
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