By Dave Elliott
Renewable energy technologies are usually considered to have low environmental impacts compared with conventional energy systems. That seems obvious in terms of direct emissions of carbon dioxide and other greenhouse gases – for most renewables (biomass apart) there are none. Similarly for emissions of radioactive materials – none. However, the use of renewable sources does lead to some impacts, most of them being small and local. How can they be assessed and compared?
By Liz Kalaugher
Sometimes I wish I had more of a head for heights. Saana’s southern slopes are steep. On Tuesday they didn’t just see the installation of temperature kit, they were also the scene for two new vegetation surveys as Peter le Roux extended a transect – a line of measurement points – begun by two other researchers.
First we headed up past some scree to around 850 m, 100 m above the two sites already measured. Here le Roux created an independent point. It’s not part of a grid plot but will help the team get an idea of how the plant-life varies across a wider area. After marking the centre with a small wire hoop in the ground and some orange forestry tape that will biodegrade in about three years, he laid out other markers 5 metres to the north, south, east and west. Each of these compass points in turn was enclosed by a 1 m x 1 m metal frame criss-crossed with cord at 10 cm intervals, like a giant empty crossword grid. Le Roux estimated the amount of each plant occurring in the letter squares to give the percentage vegetation cover overall.