It is a matter of shame that even 57 years after Independence around 60 per cent of our rural population has no electricity. They still use 180 million tonnes of biomass per year for cooking on primitive wood stoves and have no clean drinking water. India, which has an active space and nuclear programme, has not provided technologies to light up the lives of millions living in rural areas. 
Cooking and lighting, the two basic necessities constitute 75 per cent of total energy consumed by rural households. A user-friendly and quality product to satisfy these needs from locally available resources like solar, wind and biomass can go a long way in improving the quality of their life. 
Rural population desires the same quality of life as urbanites, which poses a great challenge for scientists and technologists to satisfy their needs. In this regard, the emerging areas of bio and nanotechnology can provide effective solutions. Tinkering with existing solution will not solve age-old problems, but the application of sophisticated science and technology will. 

Cooking fuels
For cooking, gaseous and liquid fuels from locally available biomass provide safe and convenient energy. Biogas has been used for 80 years in rural areas and has been produced inefficiently in the existing biogas generators. They require a considerable amount of cowdung and other nitrogenous material and are not suitable for a household with less than three to four cattle. Besides, their gas production time is about 20-25 days. There are also problems of gas production during winter and improper mixing of inputs like biomass, night soil and cow dung. Biogas, which is a mixture of methane and carbon dioxide cannot be liquefied and requires high pressure (>100 atmospheres) to compress it so that it can be used over extended periods. 
There is need to develop extremely efficient biogas reactors to maximise the production/unit of biomass inputs. Optimisation of biogas production from a reactor requires sophisticated electronic-based controls and biochemical engineering technology. This can be further helped by use of genetically engineered microbes, which substantially increase gas production efficiency. The second area is to develop appropriate storage materials, which can store biogas at medium pressures. 
Recent experiments show that biogas can be stored at medium pressures (< 40 atmospheres) in hydrates, porous carbon and porous organic structures similar to those used in hydrogen storage. Thus a scenario can be thought of whereby micro-utility companies can be set up in rural areas which will buy locally available raw materials like cow dung and biomass, and will use them in a high tech biogas reactor to efficiently generate biogas. This gas can then be stored in small cylinders lined with gas absorbent structures and then transported to households like LPG cylinders. This will revolutionise the cooking system in rural areas. A small high tech utility with optimised gas digester can afford to do it whereas for a household it might be too costly. 
Similarly, liquid fuels like ethanol, biodiesel and pyrolysis oil from biomass can be used for cooking. The use of multipurpose crops like sweet sorghum (pioneered by the Nimbkar Agricultural Research Institute) does not take away land from food production. The use of genetically engineered microbes for converting cellulosic material into sugars and high yielding hybrids of crops producing biodiesel can help in producing these fuels via small rural based utilities. There is however need to develop stoves running on these fuels. These biofuels produce large amount of soot and thus sophisticated combustion science and technology is needed in burning them to produce blue flame. Recently NARI has developed an extremely efficient stove running on low concentration of ethanol.

Rural lighting
For rural lighting technology there is need to again look closely at the liquid fuel lighting systems. One of the best systems still in use is a pressurised mantle lamp generically called petromax where the combustion of kerosine lights up the rare earth oxide (REO) mantles. These mantles have not changed since their development in late 1880s and have very low light efficiency (called efficacy) of about ~2-3 lumens per watt (lm/W). In comparison the efficacy of a light bulb is ~10-15 lm/W and 50-70 lm/W that of compact fluorescent lamps (CFL). 
With nanotechnology it is possible to develop new materials for these mantles so that the use of rare earth oxides is reduced and their efficacy is increased. With increased efficacy, liquid fuel lighting can become superior to electric lighting in terms of overall power plant-to-light efficiency. Presently the overall power plant-to-light efficiency for fluorescent lamps is ~14 lm/W. This includes thermal power plant efficiency of 30 per cent, transmission and distribution (T&D) losses of 20 per cent and fluorescent lamp efficacy of 60 lm/W. Thus a liquid fuel lamp running on locally made fuels like ethanol, biodiesel or pyrolysis oil with efficient mantles can be an excellent distributed light source for rural areas. 
Research is also needed in developing better substrates for mantles since they break often and have to be replaced frequently which increases the running cost of such lanterns. Space age materials such as those based on ceramics and carbon-carbon composites can make them durable. With such mantles the liquid-based lighting can become rugged besides being efficient. 
Micro-technologies for producing electric power from heat and fuels like ethanol can also help in rural lighting. Nanotechnology is helping develop efficient thermoelectric (TE) elements, which directly produce power from heat. These elements if attached to cookstoves can produce 40-50 W power, enough to light up a household via light emitting diode (LED) lamps. Similarly, nanotechnology is also helping produce microturbines and microengines. These 50 paise coin size engines capable of running on fuels like ethanol and methanol can produce 8-10 W of power to light a household via LED lamps. With this system the problem of bulky batteries is eliminated since the energy is stored in the fuel itself. 
Any technology becomes attractive if it is economically viable. R&D helps in increasing the efficiency of a technology and hence improving its economics. Preliminary economic analysis for rural India shows that the liquid and gaseous fuels based lighting and cooking technologies could be a Rs 25,000-30,000 crore industry. This can produce substantial wealth in rural areas. However, to achieve this there is need to set up a National Technology Mission on Cooking and Lighting Energy. This will help lay out the blueprint of R&D and at the same time bring together the stakeholders like government, R&D labs, NGOs and the corporate sector.
(The writer is Director of Nimbkar Agricultural Research Institute (NARI), P.O. Box 44, Phaltan, Maharashtra 41552. E-mail: anilrajvanshi@gmail.com)