12 March 2009
How to heat water 101
Contrary to popular belief, a solar water-heating system can have a payback period of two years, according to researchers in India.
With an eye toward advanced technological approaches to alternative energy sources such as photovoltaic cells for solar power and harnessing wind and wave with elaborate systems to generate electricity, costs of these systems may be prohibitive for applications in the developing world. With the concept that technology will help advance the alternative energy cause, researchers often ignore the fact that a mundane process such as heating water might works best by using direct heat from the sun rather than including a waste energy-conversion step.
After evaluating the various costs and benefits involved in solar hot-water production, researchers Vivek Khambalkar, Sharashchandra Gadge, and Dhiraj S. Karale at the Dr Panjabrao Deshmukh Agricultural University, in Maharashtra, India, compared solar hot-water production per liter with electrical energy approaches and found solar heating is 57% of the internal rate of return.
Solar energy is the only renewable energy source that has wide range of uses with commercial viability, according to the researchers. Solar energy provides water heating, air heating, and electricity through various modes of applications. The use of solar energy for thermal purposes is the most cost-effective way of utilizing the resource. A solar water heating system satisfies the need of warm water, they added.
The payback time for the initial investment in equipment and installation is two years. This compares very well to a photovoltaic system used for electricity generation if it were only being used to heat water. Photovoltaics have a payback period of at least a decade and sometimes double that.
The solar hot water system used in the study is at the Jijau hostel, part of the Dr Panjabrao Deshmukh Agricultural University campus, in Akola, Maharashtra state, India. The team estimates the system will effectively pay for itself five times over, given an estimated working life of about 20 years.
For related information, go to www.isa.org/manufacturing_automation.