Renewable Cement Production?
Cement is a very important commodity in the modern world. It is combined with sand, gravel and water to create concrete, a cheap, durable and strong building material. Lime stone is the basic ingredient for cement:
Cement factory ENCI near Maastricht in the South of The Netherlands. ENCI brought down its coal consumption and replaced 90% of it with alternative fuel based on waste: household waste, sewer sludge.
Cement production is very energy-intensive, which generates a lot of CO2. The embodied energy of cement mortar (1:3) is 1.33 MJ/kg, which boils down to 0.208 kg CO2/kg cement.
ENCI has shown that it is possible to ban coal almost completely and replace it with waste that would otherwise have landed on a landfill.
Dutch language video. Recycling old concrete into new bricks.
In order to create stone and bricks it is not necessary to start all over again from basic limestone to create cement. Old stones and concrete can be recycled into new bricks, which saves a lot of energy, as the video shows.