SCIENCE & TECHNOLOGY

Biomass gassification
Radhakrishna Rao
T
aking electricity to the not so thickly populated, isolated rural settlements spread across the country from the central power grid has been found to be a costly and unreliable proposition on account of the heavy transmission losses and a poor load demand.

Women can produce sperm
Steve Connor
W
omen might soon be able to produce their own sperm in a development that could allow, say, lesbian couples to have their own biological daughters, according to a pioneering study published recently.

Prof Yash Pal

Prof Yash Pal

PROF YASH PAL
THIS UNIVERSE

The number of neutrons is nearly equal to the number of protons in the nuclei of light elements. Then why does the number of neutrons go on increasing as we go towards heavier elements such as Uranium?

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Biomass gassification
Radhakrishna Rao

Taking electricity to the not so thickly populated, isolated rural settlements spread across the country from the central power grid has been found to be a costly and unreliable proposition on account of the heavy transmission losses and a poor load demand.

As such, energy experts have highlighted the need for going in for local specific, decentralised energy systems that can be sustained with the locally available resources.

Abundant availability of agricultural wastes, including bagasse, in the predominantly farming, rural settlements of India is a major plus factor for generating energy at the local level to meet the rural energy needs in an economically viable fashion.

According to the Ministry of Non-Conventional Energy Sources (MNES), there is more than 1,700-MW potential for producing gas from biomass, including agricultural residues, which can easily help power 1.25 lakh villages that are yet to be electrified.

Biomass gassification technology, which has been around for more than three decades, now has proved to be a cost effective, ecofriendly system to meet the rural energy requirements. In fact, biomass, gasification, which involves the production of producer gas — a mixture of carbon monoxide, methane, hydrogen and carbon dioxide is fast picking up in India as a major alternative energy source.

In the isolated Sunderban area of West Bengal, biomass based gassification plans are supplying power for lighting and pumping water.

Moreover, biomass can also be used for the production of heat and electricity. This process is called cogeneration. Cogeneration is feasible in the sugar industry, rice mills as well as paper and textile mills.

For instance, by upgrading the steam generation capacity of sugar mills, steam produced in excess of their process heat requirement can be utilised for power generation.

Meanwhile, in a development of significance Cummins India and the Bangalore-based Indian Institute of Science (IISc) have gone in for commercial tieup aimed at promoting the biomass gassification system designed and developed by IISc. According to Prof P.J. Paul of IISc who is one of the architects of this biomass gasification system, “our technology package known as Open Top Reburn Down draft biomass gassifier generates gas from a range of biomass that comprises forest residues, and agricultural wastes.”

Indeed, as pointed by Paul, the cost of energy generated through biomass is reduced substantially through the gassification route.

Pampraveen Swaminathan, Vice-President of power generation business at Cummins India, drives home the point that the biomass gassification provides a significant life cycle cost advantage over hydrocarbon and ultimately leads to the development of a sustainable energy system.

It has been computed that biomass gassification generates 1 MW of power at around Rs 2-3 crore. On the other hand it costs about Rs 35-40 crores to generate 1 MW of power through the solar photovoltaic route.

India’s first community based biomass gassifier power plant at Kabbigere, 30 km from Tumkur in Karnataka, is generating 0.5 MW of power to feed the central power grid and ensure round the clock, reliable power supply to five villages for both irrigation and domestic purposes.

As pointed out by Anil K. Rajvanshi of Nimbalkar Agricultural Research Institute (NARI) which operates a biomass gassification plant working on agricultural residues such as sugarcane leaves and wheat straw, India produces an estimated 600-million tonnes of agricultural residue per year.

He points out that if all this waste is gassified it can produce 79,000 MW of power — about 60 per cent of the total power available in the country. Says Rajvanshi, “It is feasible to set up a biomass based power plant of 10-20 MW capacity to cater to the needs of about 100 villages. In this way rural energy needs in India can be fully well met.”

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Women can produce sperm
Steve Connor

Women might soon be able to produce their own sperm in a development that could allow, say, lesbian couples to have their own biological daughters, according to a pioneering study published recently.

Scientists in Britain are seeking ethical permission to produce synthetic sperm cells from a woman’s bone marrow tissue after they have shown that it possible to produce rudimentary sperm cells from male bone-marrow tissue.

The researchers said they have already produced early sperm cells from bone-marrow tissue taken from men. They believe the findings show that it may be possible to restore fertility to men who cannot produce their own sperm naturally.

However, the results also raise the prospect of taking bone-marrow tissue from women and coaxing the stem cells within the female tissue to develop into sperm cells, said Prof Karim Nayernia of the University of Newcastle upon Tyne.

Creating sperm from women would mean they would only be able to produce daughters because they Y chromosome of male sperm would still be needed to produce sons. The latest research brings the prospect of female-only conception a step closer.

“Theoretically is it possible. The problem is whether the sperm cells are functional or not. I don’t think there is an ethical barrier so long as it’s safe,” Professor Nayernia said.

“We are in the process of applying for ethical approval. We are preparing now to apply to use the existing bone marrow stem cell bank here in Newcastle,” he said.

“We need permission from the patient who supplied the bone marrow, the ethics committee and the hospital itself,” he added.

If sperm cells can be developed from female bone tissue they will be matured in the Laboratory and tested for their ability to penetrate the outer “shell” of a hamster’s egg a standard fertility test for sperm.

“We want to test the functionality of any male and female sperm that is made by this way,” Professor Nayernia said.

However, there is no intention at this stage to produce female sperm that would be used to fertilise a human egg, which would require the approval of the Human Fertilisation and Embryology Authority, Professor Nayernia said.

— The Independent

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PROF YASH PAL
THIS UNIVERSE

The number of neutrons is nearly equal to the number of protons in the nuclei of light elements. Then why does the number of neutrons go on increasing as we go towards heavier elements such as Uranium?

Let us start with some simple qualitative discussion. The lightest atom is hydrogen. Its nucleus is a proton. The chemical properties of hydrogen arise from the fact that its atom can have only a single electron around the nucleus to make the atom electrically neutral. We cannot make an atom with a nucleus of two protons, because the two protons cannot be confined within the nucleus — electrical repulsion between the two positively charged protons would split then apart. So we try putting in an electrically neutral particle as a companion of proton. The nuclear force between the proton and the neutron ensures that the nucleus is stable. A single electron in the orbit of such a nucleus makes a viable atom. This is the atom we call heavy hydrogen. We can try making yet another isotope of hydrogen by adding another neutron to the nucleus. It turns out that this does work, but just about. The resulting atom is called tritium, it is radioactive and decays with a half life of 12.3 years.

One can go on adding neutrons to the nucleus to increase its mass and atomic number and it is found that the abundant and stable nuclei are those that have nearly equal number of protons and neutrons till we reach the nucleus of iron. Stability is ensured because the force of electrical repulsion of the protons balances the short-range attractive nuclear force between protons and neutrons. Beyond iron the short-range forces of protons and neutrons cannot keep in reign the long range electrical force between protons unless the number of neutrons is increased faster.


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