Technology Development

Brief History

Rising prices of fossil fuels and growing environmental concern has lead the governments around the world to encourage energy efficiency in the industry. Here we look at alternate sources for heating water and drying process based on Solar Energy.

Solar Water Heating System - Current Developments

Solar Water Heating (SWH) systems can contribute significantly to the global energy need for heating. In 2009, the International Energy Agency (IEA) reported that global energy demand for heat represented 47% of final energy use, higher than final energy for electricity (17%) and transport (27%) combined. The large proportion of heat in final energy demand explains the substantial contribution that renewable heat – and thus solar heat – could make in meeting the ever increasing energy needs of the world. SWH systems have seen an average annual growth of 12% between 2000 and 2010. During 2011 alone, the sector is estimated to have grown by 25% to 245 giga watt thermal (GWth) output worldwide. This significant development cannot be ignored considering the fact that the regions and countries adopting this technology have similar or lesser solar irradiance as compared to Pakistan.

China's Adoption of SWH

China is a net importer of fossil fuels and the economic growth that it has seen over the decades has resulted in ever increasing desire to find alternates to reduce this balance. To achieve this goal and to fulfill its energy needs China has really taken a lead in the adoption of SWH systems for domestic and industrial requirements. The installed capacity alone in China is 117.6 GWth, which is 47% of the total installed capacity in the world. Besides adopting this sustainable technology China has also taken a lead in the manufacturing of these systems which has significantly decreased the cost of these system and made them more economically viable

Prospects in Pakistan

Pakistan is seeing its worst energy crisis since its independence. This has directly impacted the industrial growth through prolonged cuts in electricity and natural gas supply. This has forced the individual industries to look for alternates that are more costly than the primary sources and has resulted in significant increase in energy costs. The export oriented industries like textile and leather are finding it difficult to compete in global markets.

Geographical location and climatic conditions make Pakistan a suitable country for adoption of this sustainable and economically viable technology. Lahore has an average solar irradiance of 16.85 MJ/m²/day and Karachi has 19.5 MJ/m²/day. To bring in perspective the average solar irradiance for major Chinese cities like, Shanghai, Nanjing and Hangzhou, are 12.49, 12.41 and 11.36 MJ/m²/day respectively. This makes Pakistan even more suitable for use of SWH systems than China.

Available Technoloigies

For tanning process non-concentrating solar thermal technologies are ideal. There are two main types:


1. Flat plate (glazed and unglazed) and

2. Evacuated Tubes


88.3% of all SWH systems are based on these two technologies. The principal behind absorption of solar energy is the same in both systems but evacuated tube collectors are more suitable for the climate and environment here in Pakistan as it performs better when ambient temperature is low as is the case during winter, sky is over cast as in monsoon and winter season here and air has dust particles.