Work is taking place on connecting key buildings in Cardiff Bay to a new low-carbon heat network.
The £15.5 million project - the first of its kind in Wales - is expected to save 10,000 tonnes worth of carbon emissions when its complete.
Last month, Cardiff and Vale College became the first customers to be connected to the network, followed by the former office block at Scott Harbour, which has now been renovated into an apatment block.
In the coming weeks, other major buildings in the Bay will be connected, such as the Wales Millennium Centre and the Senedd.
Cllr Dan De'Ath, cabinet member for climate change at Cardiff Council, said: "The heat network provides customers with an affordable, reliable and sustainable source of heat and hot water and has the scope to expand further over time."
"The moment a building connects, it eliminates the need for gas boilers and achieves an 80% cut in carbon emissions."
"It's a complex project to carry out, but an incredibly simple idea at the heart - capturing heat that already exists but is currently being wasted and transporting it to where it can be used instead of burning fossil fuels."
"What we have built is the first city-scale network of its kind in Wales. It represents a significant investment in the long-term infrastructure needed to ensure we play our part in tackling the global challenge of climate change, and building a stronger, fairer and greener Cardiff."
It's taken four years to build the network, which captures heat from steam aleady poduced as a by-product of the process that powers electricity-generating turbines at the Vindor energy recovery facility at Trident Park.
The heat is then transported through a network of highly insulated pipes to buildings across Cardiff Bay, where it provides a sustainable source of heat and hot water.
This is only the first stage of the project, which has been funded through a UK Government grant and a Welsh Government loan, with talks underway about extending the scheme further into the city centre.
Because the network is designed to be 'heat source neutral', it could potentially be connected to alternative or additional heat sources such as the groundwater or deep geothermal heat that exists beneath the streets of the Welsh capital.
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