It's not hard to find people arguing against the greater use of renewable energy sources by making the following kind of argument:
(Renewable Technology X) can't replace our current energy use because of (Insert Well-Known Reason), so it's pointless to pursue its development.
The Well-Known Reasons often boil down to what the industry calls "intermittency" -- the inability of the given energy technology to provide reliable amounts of power. And, constructed as that straw man, it's true: photovoltaics are ineffective at night; wind turbines are non-productive in still air. But as we've said here time and again, nobody is talking about replacing the entire energy infrastructure with a single production source. What will allow renewable energy to succeed is a distributed mix of a variety of sources connected via a smart power grid.
Now researchers at the Environmental Change Institute at Oxford University are arguing the same thing.
[Dr. Graham] Sinden initially looked at just three generation technologies: wind, solar and dCHP [domestic combined heat and power] — in effect, hi-tech domestic boilers, which produce electricity as they heat water. He ran computer models of power output based on weather records going back up to 35 years, and found that electricity production could be optimised by creating a mixture of 65% wind, 25% dCHP, and 10% solar cells. The high proportion of wind is because the wind blows hardest in the winter, and in the evening — when demand is highest. The dCHP also produces more at peak times, when demand for hot water and heating is also strongest. Solar makes a smaller contribution, and produces nothing at night. But it is still important to have it in the mix as it kicks in when wind and dCHP production is lowest.
It is also essential to disperse the generators, whether wind turbines or rooftop solar cells, as widely as possible. By increasing the separation between sites, you can be sure that power is always being generated somewhere and so smooth out the supply curve.[...]Putting these figures together with estimates of Britain's available renewable resources, wind (onshore and offshore) could realistically provide some 35% of the UK's electricity, marine and dCHP each 10-15%, and solar cells 5-10%. In other words, more than half the UK's electricity could ultimately derive from intermittent renewables.
This contrasts to current plans, which call for renewables to amount to about 20% of the UK's generation needs.
DCHP systems are particularly interesting -- increasingly common in Europe, much less so in the US. In a separate article about Sinden's argument, dCHPs are described thusly:
The dCHP takes the form of gas-fired domestic boilers which generate electricity as they warm water using a Stirling engine, producing 1 kilowatt of electricity for every 8 kilowatts of heat. So dCHP produces most electricity when demand for hot water and central heating is greatest, neatly coinciding with peak demand for electricity.
(We posted about a commercially-available Stirling engine dCHP back in December of 2003.)
This, of course, only accounts for the production side of the equation. There are myriad examples of ways to improve the efficiency of buildings (phase-changing wax insulation, anyone?), and increasingly sophisticated tools for monitoring and reducing power consumption (I'll be writing about a new one in the coming days). Amory Lovins makes the point again and again -- efficient use is even more important than efficient production.
Mixed/Distributed Renewables + High Efficiency Living = The Bright Green Future.
