The mole, symbol mol, is the SI unit of amount of substance of a specified elementary entity, which may be an atom, molecule, ion, electron, any other particle or a specified group of such particles; its magnitude is set by fixing the numerical value of the Avogadro constant NA to be 6.022 141 29 × 1023 when expressed in the SI unit mol-1. In metrology in chemistry, the realization of mole in all types of chemical entities is done using variety of primary methods of measurements in terms of the amount of substance concentration (mol/m3), amount of substance content (mol/kg) or amount of substance fraction (mol/mol). Three widely used methods to realize the mole are: gravimetric, use of the ideal gas law and electrolysis. At CSIR-NPL, under gas metrology activity, we prepare primary gas standards (especially for greenhouse gases, and criteria pollution gases and particulate matter) by gravimetric method, and realize mole as mol/kg or mol/mol.

In the fast moving generation, we are dependent on electricity for every small need varying from communication to internet. Unfortunately generation of electricity from the traditional fossil fuels is expensive and more importantly hazardous to the environment and public’s health. Fossil fuels e.g. oil, coal or natural gas, releases harmful particles into our air, including carbon dioxide, nitrogen oxides, sulfur dioxide, methane and mercury compounds .

The solution to the above problem lies in Clean Energy. Clean energy is heat and electricity produced from renewable sources, generating little or no pollution or emissions. It includes solar energy, wind energy, hydropower energy, and geothermal energy. Renewable energy is cleaner, cheaper, safer source of energy as compared to the fossil fuels. With the current technologies and efforts we have the potential to produce 40% of the electricity from renewable resources by 2030 and 80% by 2050.

Recently global investments have also increased in the clean energy sector. According to UNEP, 2014 brought a rebound of green energy investments worldwide with a surge of a solid 17% to $270 Billion. Brushing aside the challenge of sharply lower crude oil prices this sudden increase reversed the investment dip of the past two years and was mainly driven by investments in solar and wind energy. China, US and japan were the top three countries in renewable energy investment. A key feature of the 2014 result was the rapid expansion of renewables into new markets in developing countries. Investment in developing countries was up 36% on the previous year and came the closest ever to overhauling the total for developed economies. Indian government has recently started Jawaharlal Nehru National Solar Mission with an aim of deploying 20,000 MW of grid connected solar power by 2022 which will decrease the cost of solar power generation through various policies. All these recent activities and growing interest shows that people are aware of the clean energy and in the coming times clean energy will be the latest trend.