NE SCIENCE & TECHNOLOGY BUREAU
HYDERABAD, JAN 9
An extensive analysis by Indian Institute of Technology Hyderabad and Monash University, Australia Researchers has suggested geothermal energy – the use of the earth’s heat to generate power – is better than photovoltaic energy in terms of carbon dioxide emissions. The researchers also suggest that a combination of renewable energy technology must be adopted in this era of dwindling fossil fuel reserves and increasing greenhouse gas emissions.
This analysis was undertaken by Prof. D. Chandrasekharam, Department of Civil Engineering, IIT Hyderabad, and Prof. G. Ranjith Pathegama, Department of Civil Engineering, Monash University, Melbourne, Australia. Their Research paper was published recently in the reputed peer-reviewed journal Geomechanics and Geophysics for Geo-Energy and Geo-Resources.
Speaking about their analysis, Prof D. Chandrasekharam, said, “While solar power does have benefits over conventional energy sources, is the hype surrounding its apparent ‘greenness’ justified? Solar power is far from the zero-emissions energy source that it is claimed to be.”
Their study involved lifecycle assessment of renewables. Around 10 tonnes of quartz is needed to manufacture solar cells that can generate 1 megawatt of electricity from Sun. 1 MWe of electricity can support about 20,000 people annually.
Further, Prof D. Chandrasekharam, said, “Imagine how many tonnes of quartz has to be mined to support millions of people in the countries! A Solar pv cell involves two important stages: i) producing metallurgical grade silicon (MGS) and ii) producing electronic grade silicon (EGS) from quartz. In the first stage an amount of 1756 thousand tonnes of CO2 is released, and a similar amount of CO2 is released during the conversion of EGS to ingots.”
The total CO2 emissions during the lifecycle of a solar pv cell are about 3312 million kg. This is far higher than geothermal energy source, which emits about 450 g/ kWh generated reports the paper.
According to the recently published report by International Energy Agency (IEA), under the sustainable development policy, proposed for adoption to mitigate CO2 emissions (Year 2040), nearly 54 billion cells are required to meet the generation target of 14,139 TWh. This amounts to releasing huge amounts of carbon-dioxide into the atmosphere instead of conserving carbon dioxide says the researchers.
While certain alternative energy sources such as solar power are being widely considered among the green energy technologies, no type of energy can be completely environmentally neutral. A comprehensive assessment of all costs and benefits must be undertaken for all green energy technologies.
“Unlike other renewables, geothermal energy can supply base-load electricity and the waste after its life cycle, unlike solar PV, is negligible. The best way to go forward is to choose a combination of technologies that can minimize harm to the environment, not chase the horizon of zero harm”, write the researchers in their recent paper.
The researchers analyzed the life cycle assessment solar cell technology in terms of the environmental impacts during construction, operation and decommissioning stages.
In addition to the carbon dioxide emissions associated with the mining of silica and its conversion into electronic-grade quartz to be used in solar cells, disposal of waste is a huge environmental concern writes the researchers.
Solar photo voltaic does not emit carbon dioxide during it electricity generation but this cell has already emitted large quantities of carbon dioxide during its evolution. Then how can you give green energy tag to this source say the researchers.
According to the “End-of life management of solar photo voltaic panels” publication by the International Renewable Energy Agency (IRENA), globally 60 to 75 million tonnes of solar pv panels waste will be by 2050 that cannot be recycled. Some facts are hard to digest say the researchers.
