A book on renewable energy, written by former Bradford University lecturers Bill Shepherd and his son David, has been sent to the White House and 10 Downing Street.

As well as helping electrical engineering students with their studies the pair hope their book Energy Studies will influence world leaders such as US President Bill Clinton and Prime Minister Tony Blair when it comes to energy-related policy decisions.

Professor Bill Shepherd, 71, has a home in Shipley but lives with his wife Elisabeth for most of the year in the USA where he has lectured in renewable energy studies and electronics at Ohio University since retiring from Bradford in the mid-1990s.

He said: "We've sent copies to Tony Blair and Bill Clinton, which have been politely acknowledged, because the message that we're running out of oil can only really be addressed by heads of state.

"We're hoping they'll start to activate bigger programmes to research and develop renewable energy resources.

"We're trying to persuade the great and the good to do something about our energy future.''

The book scientifically examines various forms of renewable energy such as solar, wind and hydroelectric as well as nuclear power and that generated by fossil fuels like gas, coal and oil.

Professor Shepherd said: "We take oil for granted but there's only enough left to last another 60 years and that's where renewable forms of energy come in.

"The book concludes with a look at the future and what energy sources will be available to sustain the world's growing population.

"Solar and wind energy are two of the big ones and although it's a dirty word in America and Britain, nuclear energy will also be a vital part of the future.''

Published by World Scientific Publications, the £33 textbook grew out of courses Professor Shepherd and his son Dr David Shepherd, 41, of Shipley, have run on renewable energy.

Despite being on opposite sides of the Atlantic for much of the time the pair - currently working on a revised edition - collaborated on the book via their computers.

Professor Shepherd said: "There are very few books on the subject around and this is a general survey covering almost the whole field.

"It's going down very well with the undergraduate students at Ohio but it's something that can be taught at various levels and would make a terrific text book for A level general studies over here.''