Business news in brief: Marks & Spencer HIGH street stalwart Marks & Spencer yesterday signed a deal to buy electricity generated at an "anaerobic digestion" (AD) plant in Cumbernauld, which uses bacteria to turn left-over food scraps into energy. M&S already supplies the plant, which is run by Energen Biogas and Shanks and which opened in October 2011, with food waste. The retailer agreed to buy 19,000MWh of electricity a year, enough to power 33 of its Simply Food shops. 3D to sell Dundee's CarieScan Investors yesterday gave the go-ahead for 3D Diagnostic Imaging to dispose of its Dundee-based CarieScan dental technology subsidiary and turn itself into an oil and gas investment company. Shareholders at an extraordinary general meeting voted in favour of changing the Isle of Man-based company's name to 3D Resources. The Aim-quoted firm has raised £114,000 from new investors, with £100,000 being pumped into CarieScan to be hived off. Aon swoops for Caithness business Babcock International Group has sold its pensions administration office in Caithness to global insurance company Aon for an undisclosed sum. The office currently employs 33 people providing administration services to pension schemes with around 80,000 members. Aon Hewitt, the human resources division of Manchester United shirt sponsor Aon, said the firm plans to expand its presence in the public sector pensions and is "committed to growing the business in Caithness." Facebook enjoys best day on Nasdaq Social network operator Facebook yesterday enjoyed its best day since its stock market debut in May after advertising revenues from mobile phones doubled during its third quarter. The firm posted a $59 million (£37m) loss late on Tuesday night after making a big accounting provision against tax. But advertising revenues rose 36 per cent to $1.1 billion.