Renewable energy’s place as part of the global “energy balance” is a delicate scale.
As its prospects and contribution rise, limitations also appear.
The main elements here involve…
– The intermittent nature of solar and wind power (the sun doesn’t shine 24/7, and the wind isn’t always blowing) means alternative, more traditional, generation sources, must remain online to cover the slack periods or those in which demand peaks;
– The flattening out of pricing advantages in the absence of new rounds of government credits;
– And that the higher unit production costs that are absorbed by end users through existing state requirements include mandated portions of renewable energy.
The world’s overall reliance on renewables like solar and wind has and will continue to rise. But that growth has also raised questions about how much higher that reliance can move.
This is particularly troubling for large regions of the world in desperate need of additional electricity like the Caribbean and Puerto Rico.
There, only one, potentially dangers solution remains – low-quality coal.
And even that might not be an option for some.
Aside from a breakthrough in battery technology, which would allow for some extended storage across the power-generation sector – there’s only one other possible near-term remedy for renewables…
A Pricey Situation
For renewables to carve out a larger place in the global energy balance, we’re going to have to find ways to cut the cost of production, while improving the flexibility of power availability at the same time.
Fortunately, there has been one promising development on that front recently.
It involves combining solar and wind in what can best be described as a “hybrid serialized” process.
Vestas Wind Systems, the Danish world leader in wind power systems, and Madrid-based EDP Renewables (EDPR) have installed a hybrid demonstrator that feeds direct current from a solar photovoltaic (PV) array into a wind turbine that then exports power to the grid through a single converter.
The two companies installed the Vestas V112-3.0MW turbine and a new 372kW solar PV array at EDPR’s Janda III wind farm at Cádiz in southwestern Spain.
The system looks like this:
Photo source: EDP Renewables
Power from the solar PV panels is fed to the turbine as direct current, which is then converted and transformed by the turbine’s power conversion system, which Vestas upgraded especially for the project, to export power to the grid.
Now, this approach may comprise one of the most intriguing ways to address a problem I have addressed on several occasions here in Oil & Energy Investor – inversion.
Solar’s Holy Grail
Inversion has become the “Holy Grail” in solar technology. It addresses a problem I have wrestled with for some time: solar (and wind) power is initially harvested as direct current (DC) and must be converted into alternating current (AC) to move on the power grid.
“Inversion” is the name for this conversion that makes solar and wind power usable on the AC-only power grid.
Unfortunately, early inverters would sacrifice at least 50 percent of the power in the transition from DC to AC.
While there have been improvements in the existing process, current inversion still sacrifices a half or more of the energy harvested by the time it reaches transmissions lines.
Reducing this loss would be a major advance in renewable power production efficiency.
By connecting wind and solar through the turbine’s electronics and using its full-scale converter, the number of converters is reduced, according to both Vestas and EDPR.
In a joint release this week, both companies noted that the approach lowers equipment costs as well as the cost of the electricity produced.
In an interview released by Windpower Monthly on March 28, EDPR technical director Bautista Rodriguez, said: “The development and running of this demonstrator is an interesting opportunity to test some of our hypotheses on the hybrid power plants of the future.,” adding, “Furthermore, it gives us an opportunity to explore wind and solar technology synergies in close collaboration with Vestas.”
Of course, one demonstration project does not make a trend.
But the consolidation of both solar and wind in a seamless sequence may prove to be a nice complement to other advances in hybrid technology underway in Europe and Asia.
Moving the power sector into an expanding use of multiple energy sources also requires tailoring approaches to meet insular local challenges.
That puts forward hybrid systems like the one being demonstrated in Spain, if it’s found to be commercially viable, as attractive options.
This is unquestionably the case in providing smaller modular solutions to local electricity needs, especially in areas hard to reach by more conventional solutions.
By Kent Moors
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