Direction (Qs.1 to 10): Read the passage carefully and answer the questions given below it. Certain words/phrases are given in bold to help you locate them while answering some of the questions.

Energy storage is a tricky subject, and yet immensely valuable in the long term, but only a few scientists are working on the topic in India. One of them is AK Shukla, distinguished professor at the Indian Institute of Science (IISc) in Bangalore. He is now developing a hybrid supercapacitor, a device that can store electrical energy and has some advantages over the lead acid battery. His first exhibit is a small prototype, slightly bigger than a large matchbox, weighing about two kilos. It can hold enough charge to light a lamp for five hours. The market is thirsting for more. The lead acid battery was invented long ago, as far back as the year 1859. It is still going strong, being the primary means of electricity storage in India, and sustains a growing market of Rs.25,000 crore. But it is not good enough for two of the biggest future applications; electric cars and grid storage. For those we need big breakthroughs in electricity storage, and the supercapacitor, hybrid of otherwise, is just one of the options being tried. “We can charge the supercapacitor much faster than the lead acid battery,” says Shukla.

Batteries hold energy through a chemical change in a liquid, and this change is reversed while drawing current from it. Capacitors use physics and not chemistry. These store energy by keeping two mutually isolated metal plates with equal but opposite charges, and discharges it when the plates are connected.

Supercapacitors also work the same way, except that they hold a tremendous amount of charge. Capacitors charge quickly and discharge quickly, and are used when high power is needed. Batteries charge slowly and discharge slowly, and are used when you need steady supply of energy over long periods. By combining the two, scientists hope to have the best of both worlds, and provide energy as well as power, but it is not so simple in practice. Capacitors themselves are widely being tried as an alternative to battery, but are not good enough at the moment.

So, while we wait for the supercapacitor to improve, scientists are looking at other options. The world needs new storage devices because renewable energy requires them. At the moment, solar and wind energies only supplement thermal and hydroelectric power. So it does not matter too much if the sun does not shine or the wind does not blow. But if they are major suppliers of energy, as expected in a decade, we have to store their energy somewhere to use when the source shuts down. Good energy storage is thus necessary for renewable energy to take off in a big way.