Earlier this year President Obama blasted the nay-sayers ideologically opposed to renewables, comparing these “professional politicians” to the flat earthers of years gone by.
Obama chose to launch his attack from the Solar 1 plant in Boulder City, Nev., an impressive new facility with a 48-megawatt (MW) generating capacity.
Coinciding with the president’s visit the plant had just been fitted with solar forecasting devices called sky imagers. The imagers scan the skies using a fish-eye lens for a 360-degree view of the horizon and the collected data is then used to generate a 3-D weather model of the upcoming 15 minutes.
More so than Obama’s rebuke, the sky imaging software provides an answer to one of the main drawbacks of renewables which those who are in the business of bashing them like to highlight.
This is the problem of variability. In simple terms, the fact that the sun doesn’t always shine; that wind doesn’t always blow; that the sea is sometimes becalmed.
The unpredictable nature of weather makes energy output from wind, wave and solar hard to accommodate into the energy mix. This is because utilities need a consistent, smooth-flowing supply, not the hikes and troughs produced when, say, clouds obscure the sun at a solar plant or a sudden gale starts blowing near a wind farm.
Proponents of further oil and gas exploration, and of nuclear, claim variability as a fatal flaw in green energy and the reason why traditional fuels will always be needed to make up the shortfall.
In response, clean tech proponents offer the smart grid as a possible solution. The grid, which is still in its infancy, could eventually allow for power to be stored and moved around in such a way that fluctuations in supply and demand are taken care of by the grid itself.
But the smart grid is still some way off and even then, it’s unlikely to be enough on its own to compensate for the variations.
In the meantime renewable energy providers are turning to more sophisticated weather forecasting systems, like the sky imaging devices in Boulder City, to give them a more accurate assessment of what their likely power output is going to be.
These systems are cropping up everywhere across the industry and if it’s true, as Bob Dylan sang, that you don’t need a weatherman to know which way the wind blows, well, that’s because you now need a specialized computer model composed of high-resolution meteorological data and a complex set of algorithms.
Earlier this year, a team of engineers at Stanford used such a weather model to recommend optimal placement of four proposed interconnected wind farms off the eastern coast of the U.S.
The optimized grid was located in the waters from Long Island, N.Y., to Georges Bank, a shallows about 100 miles east of Cape Cod.
The model took in to account the need to offer a consistent power supply. As a result the researchers recommended placing some of the notional wind farms at near-shore locations where sea breezes blow with regularity, thanks to the daily difference in temperature between land and sea.
But even the most astute planning can only do so much to mitigate the natural variability of weather and once a wind farm is up and running, its operators need the most up-to-the-minute information to know what to expect.
That’s where companies like MDA Information Systems come in. The Maryland-based firm provides wind speed and turbine power predictions from the present and up to five days in advance.
Their detailed forecasts, for which they rely on remote sensing from aircraft and satellites, are sent to wind farms in the form of live web displays and text file data feeds. The site managers can then use this information to provide utilities with accurate predictions of their daily output.
Forecasting is not only important for integrating renewable energy power sources with the grid. It can also be used to increase efficiency. Turbine operators can make adjustments to compensate for upcoming changes in wind speed and direction. For example, if they know extreme weather is on its way — wind speeds exceeding around 25 meters per second are usually considered to be above the cutoff threshold — they can avoid costly damage to the turbines by shutting them down.
The goal of greater efficiency is behind a project currently in development in the UK’s marine energy sector.
A team, led by the University of Exeter, in western England, has came up with a series of mathematical prediction models which they claim could double current energy capture of wave power devices.
The research, carried out alongside Tel Aviv University, focused mainly on point absorbers, commonly-used floating devices with parts that move in response to waves, generating energy which they feed back to the grid. The key to making the point absorbers work better, the researchers said, was to try and ensure their response matched as closely as possible the force of the waves.
The university teams are collaborating with Ocean Power Technologies (OPT), a wave energy device maker, to develop the results from this research.
Forecasting may have an even more crucial role in the future, in part because of the phenomena that renewable energy is meant to mitigate against: climate change.
The future impact of climate change, if the scientists predictions prove accurate, could well be more extreme weather. Ironically, this means more disruption to green energy capture and a greater need for systems that can forecast those disruptions.
For instance, hydropower generation is dependent on the hydrological cycle and right now hydropower stations can predict their future output pretty accurately based on historical records of annual rainfalls and snow melts. But major shifts in the earth’s temperature have the potential to throw those cycles severely out of balance and make current prediction models obsolete. A major research project by the Federal University of Rio De Janeiro has looked into this issue.
The truth is that variability in the weather is a problem renewable providers simply can’t get around and current solutions have only gone a short way to addressing the issue. But if they’re to prove the flat earthers wrong they’ll have to get serious. Until then, to borrow another Dylan lyric, the answer, my friends, is blowing in the wind.