LONDON.- Yesterday the Mayor of London, Boris Johnson, started the enabling works on the new development of Tate Modern.

The Mayor launched the start of preparatory building works on the new Tate Modern development in the oil tanks of the former power station from which the new building will rise. Work will now start on the oil tanks, two of which will be retained as raw spaces for art and performance. Initial works that also start today include the installation of 185 piles to a depth of 25m that will strengthen the existing Turbine Hall foundations. In addition, Tate will shortly start demolition work to clear the area directly south of Tate Modern, making way for the new development.

Boris Johnson, Mayor of London said: "The genius of London is being able to spot the potential of an ageing power station and create an enormously successful gallery like Tate Modern. It is a cultural landmark and global icon and I'm delighted to support its much-needed expansion. Not only will it add to the excitement around the 2012 Games, it will extend the potential benefits of this great temple of art even further south into the Bankside area."

Nicholas Serota, Director, Tate said: "The new Tate Modern development will be an iconic world-class addition to London's skyline. We are delighted that the Mayor of London has taken with us the first steps towards its realisation. We look forward to creating one of the most exciting cultural buildings in Europe which will bring direct benefits to Southwark and London as a whole."

The plans for the new development of Tate Modern by leading international architects Herzog & de Meuron were granted planning permission by Southwark Council in March 2009.

The Switch House, to the south of the Turbine Hall, continues to house an electricity substation that serves a large area of the City and South London. EDF Energy, who occupy the substation, are completing works to modernise the station's equipment, allowing them to use a smaller amount of space in the building and freeing up space for Tate Modern to expand. The London Development Agency paved the way for the expansion by providing £7 million to fund the changes to the substation in 2006. EDF Energy is on track to complete its modernisation works and hand over the Switch House to Tate later this year.

London Development Agency Deputy Chief Executive, Peter Bishop, said:

"I am delighted that the London Development Agency's £7 million grant is laying the foundations for Tate Modern's growth. The new extension will strengthen and boost the continued regeneration of Southwark Bankside."

The new development will contribute to the local environment by opening up a new North/South route from the Millennium Bridge through the building to Southwark. Once the Switch Station is opened up, people will be able to cross the Thames, walk through the existing Tate Modern and Turbine Hall, and out onto the new plaza. From there direct paths continue into the heart of Southwark – helping to connect this whole area to the South Bank and the City beyond, and providing the catalyst for the further regeneration of this whole area.

The façade echoes that of the original power station but uses brick in a radical new way by creating a perforated brick lattice through which the building will glow in the evening. 500,000 bricks will envelop the new building.

The new building also sets new benchmarks for museums and galleries in the UK for both sustainability and energy use. By exploiting waste heat emitted from EDFE's relocated transformers and employing passive design principles wherever practicable the scheme will use 54% less energy, and emit 44% less carbon than building regulations demand.

Overall the project will also address some of the strains on the current building. The gallery was originally designed for 2 million visitors. With current visitor numbers reaching up to 5 million, there is serious overcrowding particularly at weekends. Changes in contemporary art practice mean that different kinds of spaces are desirable and additional space is needed so works can be brought out of storage and shown on a more permanent basis. Since 2000, there have been more than 2 million participants in Tate Modern's learning programmes and existing spaces cannot satisfy demand. The new building will provide over 5000sqm of new gallery space and over 1300sqm of new space for learning programmes.

The project is due to be completed in 2012 at an estimated cost of £215 million at 2012 prices. To date Tate has raised £76.5 million, which represents a third of the overall costs.