In the wake of the recent G8 summit in
Of the options available to us for replacing fossil fuels, one of the prime candidates for success is solar power generated by photovoltaic, or PV, cells.
According to the European Renewable Energy Council, by 2040 solar power will likely meet fully one quarter of worldwide energy demand, but where will that huge amount of energy – around 9 terawatt hours (TWh) – come from?
To find out, we spoke to two of the world's leading supplier of solar-cell equipment, Osaka-based Sharp and Sanyo.
We'll start with Sharp, an electronics giant that's far better known for its television sets and domestic appliances. But its most recent annual financial results show that ¥150 billion (£700 million), or 4.5 per cent of its business, came from solar cells and associated PV technology.
That shouldn't be too surprising to anyone familiar with the PV business. Based on International Energy Agency figures, Sharp has been responsible for 2 gigawatts (GW) of the 8GW-worth of solar equipment shipped worldwide to 2007 since the technology was invented in 1953.
While domestic solar panels account for a relatively small proportion of total sales, Sharp has kitted out almost 2,000 lighthouses and over 160 satellites with its various flavours of solar cell.
Given such diverse uses, it's obvious that the technology that goes into the PV business is complex, but for our purposes we can focus on the two main kinds of silicon-based solar cells.
Sharp's two 'PV pillars' are the currently dominant crystalline-type cells and the up-and-coming thin-film type. The former are suitable for use even in moderate climates, such as the
Conversely, thin-film cells use only 1 per cent as much silicon, but are only practical in countries where the Sun can be relied on to shine for much of the year.
Currently, crystalline PV accounts for 80 to 90 per cent of the world's output, but this is changing as silicon prices rise due to heavy demand from computer chip makers.
Sharp's existing plant in
One of these immense complexes, at Sakai in western
Working with a local electricity company, the cells will deliver 18MW of power to the plant, meeting 5 per cent of its energy needs and underlining how important thin-film PV cells are to Sharp.
Throw in increasing government commitment to solar energy around the world and it's clear that change is afoot.
For example, the Japanese leadership has set a target usage capacity of 4.8GW of solar power by 2010. That's equivalent to five nuclear power plants.
The numbers are clearly compelling, but what do they add up to for the end user – should the average person in then street really give a hoot?(Sharp is building a massive solar plant with one of Japan's biggest power companies, Solar panels are also perfect for powering orbiting satellites )
Sharp's Miyuki Nakayama explains that the company hopes to increase PV production with a very specific end-cost goal in mind – electricity coming out of wall sockets that costs no more than it does now:
"We believe that by reaching the cost target of ¥23 (10.7 pence)/KWh, which is equivalent to the cost of power generation using fossil fuel, will increase the market for more environmentally friendly solar systems."
Another firm with strong solar roots which is hoping that proves true is Sanyo. The newly eco-friendly company is best known in solar circles for its proprietary HIT (Heterojunction with Intrinsic Thin-layer) solar cells.
Like Sharp, Sanyo is also spending heavily to increase its PV production capabilities. Between now and 2010 it will have invested ¥70 billion (£325 million) in new facilities that will take its output of solar products to around 600MW per year.
Just next week, it will open a new plant at Shiga, also in western Japan, that will consolidate its HIT production lines in one place, while the Solar Ark we saw recently will soon house a new PV research facility.
Of course, companies can do research and build solar plants to their hearts' contents, but getting solar panels in place atop a lot more houses around the world is another challenge.
Sharp's Nakayama explains how market forces will come into play here too: "We are confident that the various applications and product line-ups Sharp is proposing to consumers will speak for themselves."
In other words, the 'build it and they will come' model applies to getting the world using renewable energy just as well as it does to fictional baseball fields.
The only difference is, this isn't a movie set and if we get it wrong at the first attempt the chances for a retake are slim to none.
Miniature organic polymers cells could power microscopic machines
Some of the smallest solar cells ever made have been successfully tested as a power source for even tinier microscopic machines.
Each cell is just over 1mm long - that's about a quarter the size of a lowercase 'o' in a standard 12-point font.
Unlike bulky, brittle silicon solar panels, the new cells are made from an organic polymer that can be dissolved and printed on to a flexible material.