Power Generation: Conventional and Renewable
This domain checks your understanding of how each generating technology converts its fuel or resource into electricity, and whether you can handle efficiency, heat rate and capacity utilisation factor (CUF) calculations.
Conventional generation
- Coal thermal: pulverised coal burns in a boiler to raise high-pressure steam, which expands through a turbine coupled to a generator; the steam is condensed and returned by the feed pump. It follows the Rankine cycle, so efficiency is capped near 40% and typical Indian subcritical plants run at 33–37%.
- Gas: open cycle (Brayton) is quick to start and suits peaking; combined cycle (gas turbine + waste-heat steam turbine) reaches about 55–58%.
- Hydro: potential energy of water at a head is converted in a turbine - Pelton for high head, Francis for medium, Kaplan for low head and large flow. Fast starting makes hydro ideal for peaking.
- Nuclear: controlled fission of U-235 heats the coolant; Indian PHWRs use natural uranium with heavy water moderator.
Renewable generation
Solar PV uses the photovoltaic effect; typical module efficiency is 15–22% and Indian CUF about 17–19%. Wind turbines extract kinetic energy, with CUF around 25–35% on good sites. Biomass, small hydro and rooftop solar are the other prominent options in Haryana, promoted by HAREDA.
Worked example: heat rate and efficiency
A thermal unit has a heat rate of 2500 kcal per kWh generated. Since 1 kWh = 860 kcal, efficiency = 860 ÷ 2500 = 0.344, i.e. 34.4%. If the same plant improves its heat rate to 2300 kcal/kWh, efficiency rises to 37.4% and coal per unit falls - a direct fuel saving.
Traps
Mixing heat rate (kcal/kWh, lower is better) with efficiency (%, higher is better); using 8760 hours for a solar plant's equivalent full-load hours instead of CUF; calling hydro 'non-renewable' because it uses a dam; forgetting that combined cycle needs a heat recovery steam generator.