Imagine if your annual electricity bill was £45 million.

Of course, for a household, there would be something very wrong if that landed on the doormat. But for a large business, yearly energy bills of more than six figures are commonplace.

The above figure is the amount Yorkshire Water pays for energy every year. The company uses two per cent of all electricity generated in the UK, and it accounts for 70 per cent of its carbon footprint.

But its own resources are being harnessed to drive down that sum. By using renewable energies in innovative ways, Yorkshire Water is making an impact, both on its energy bills and the company’s efforts to fight climate change.

“Customer demand is going upwards and we look at how we can use modern technological devices to save energy,” says climate change manager Gordon Rogers.

In 2010/11, use of its own renewable energy sources produced around ten per cent of the company’s electricity needs. It aims to increase this figure to around 15 per cent by the end of 2014/15, and to more than 20 per cent by 2020.

They are on target to achieving this, thanks to investment in groundbreaking pieces of engineering such as the hydro-generator – the first in Europe to be installed at a waste water treatment works – at the company’s Esholt plant.

The machine consists of two 12-metre long Archimedes screws that harness energy created by waste water as it flows to primary settlement tanks, where the first stage of treatment begins.

The generator is capable of providing ten per cent of the plant’s total energy needs – a saving of more than £100,000 a year. It will have paid for itself in two years’ time.

“We are lucky with the topography of Esholt which is well-suited to this,” says company spokesman Matt Thompson.

The waste received at the treatment works – which serves around 700,000 people across the Bradford district– also has potential for releasing energy.

This has been realised at Esholt through an anaerobic digester, a sealed unit in which organic materials break down into methane gas. It already produces 35 per cent of electricity on the site.

“Our greenhouse gas emission is large,” says Ben Roche, manager of energy and carbon. “Pumping water around the region and providing sewage services are energy-intensive processes.”

Over the past 18 months, the company has been developing its climate change strategy and has submitted a progress report to the Department for Environment, Food and Rural Affairs. Five-yearly plans are submitted for approval to water regulator Ofwat.

“The strategy is taking shape and this year we are focusing on taking it forward,” says Gordon. “Climate change projections tell us that there will be a long-term, gradual change with drier summers and wetter winters. We need to continuously invest. We cannot stand still.”

A process called advanced thermal conversion, which heats waste material to produce gas, is already running, and will help the plant towards producing no waste, while producing energy.

Says Gordon: “By generating our own electricity, we become less susceptible to price rises, and that in turn protects customer bills in the long-term.”

Within the next three years, new processes arriving at Esholt include a £30 million thermal hydrolysis digestion plant, which is also a first of its type in the UK. Resembling a large pressure cooker, it produces gas from sludge.

This will result in 100 per cent self-sufficiency in energy production at the plant. “Esholt is very important to us,” says Ben. “By 2015 it will be by far the greenest plant.”

Regionally, the company aspires to be carbon-neutral by 2030.

As well as hydro power, Yorkshire Water is also investing in wind energy and combined heat and power units which use gases produced through the sludge digestion process to create power. At Esholt a process called sludge phyto conditioning sees sludge mixed with green waste to create a high-quality topsoil.

Educating customers about saving water, and how to cut down use in times of need, is a vital part of the strategy. “We are lucky in that we have some very water-wise customers who are keen to play their part,” says Matt Thompson.

“It is a journey with no real end. There is more we can do as more technologies become available. It is great news for us and our customers. The rest of the industry is watching.”