Harnessing Solar energy, Options for India

Table 25: Installation Costs for Solar Air Heating System for the Tea Industry and Government
Kg of coal
saved/kg of
processed tea
Energy
produced/m 2
of solar
collector/ year
Total
collector
area
required
(million m 2 )
Cost to the
industry
(without
subsidy)
(million `)
Cost to the
government
(subsidy)
(million `)
0.15 750 kWh* 0.3 `2407 `722**
Notes: *Considering 50% thermal efficiency of solar collectors and 1500 hours/year of operation.
**Based on MNRE capital subsidy of `2,400/ m 2 of FPC using air as the working fluid.
3. Solar Cooking
Over 80% of rural households use biofuels and animal dung for cooking. A vast majority of such
homes burn firewood in traditional cook stoves (chulhas). This emits smoke and also has adverse
environmental and health effects. Additionally, the process of collecting firewood is often an
exhausting and time-consuming task. While small-scale solar cooking will benefit individual families
in terms of health, large-scale solar cooking has the potential to save considerable fossil fuel. Solar
cooking has several advantages since it requires very little maintenance, and saves cooking time and
fuel cost. The focus of this case study is on large-scale solar cooking applications with the solar
steam cooker. There are many large installations of solar cookers in India where several thousand
meals are prepared daily.
3.1. Solar Cookers
There are four major types of solar cookers: box cooker, dish cooker, Scheffler cooker and solar
steam cooker. A total of around 639,000 box solar cookers and 10,200 dish solar cookers have been
deployed so far in India. 19 The box cooker seen in Figure 20 is possibly the most widespread, and is
useful for cooking at moderate to high temperatures for a single family. The cost of a box cooker
varies from `1,800 to `3,000 depending on its size and features. 20 Indian culinary and cultural habits
make it difficult for most to replace the use of firewood with solar cookers completely, but box
cookers can supplement firewood. This will be of immense help to rural families in the reduction of
indoor air pollution, in reducing deforestation, and helping reduce the drudgery of collecting wood
for rural poor women.
For community-based cooking for up to fifteen people, the dish cooker seen in Figure 21 is a carbonfree
solution. The temperature here can reach up to 300°C, which is sufficient for roasting, frying and
boiling.
Solar Thermal Applications CSTEP | Page 95