by Alfonso Damiano
100% RENEWABLE BY TOMORROW?
Can we stop to think small?
To provide electrical power to the end user in an optimum manner, the balance between the energy produced and energy consumed
has to be determined at each instant.
To date, this condition of energy balance has been achieved with a centralized management system of the electric energy provided
by a resource, managing and overseeing the development of generation (fossil, geothermal and hydroelectric), loads and storage systems.
The introduction of generation from renewable energy sources, particularly those defined as "non-programmable" (photovoltaic and wind)
has introduced a series of random distributed variables in the supply region. These were initially considered irrelevant due to the
limited total input compared to that of thermoelectric power generating.
The explosion of photovoltaics and wind power generation has destabilized the balance of the system by introducing a series
of "disorders" that are difficult to manage. Currently, distribution companies have reacted to this situation exclusively with a
cutting action: when the production from renewable sources is not able to be integrated, the system operator intervenes disconnecting
the renewable generation equipment. The operator of renewable energy, still gets paid even though production is not utilized.
This "model of emergency management", originally introduced for wind turbines, has recently also been extended with the new energy
bill for photovoltaic plants. At this point the problem of management of renewable energy sources (RES) can no longer be ignored!
This scenario is part of the problem facing the planned European energy production from renewable energy equal to 20% of gross energy
consumption (electricity + heat + transport) and it makes it urgent to create a smart grid (smart grid) that does not dissipate the
clean energy – referred to as "noble" : renewable energy.
To quickly get a smart grid, any solution should provide management of the flow of electricity of distributed storage systems locally.
In this way the renewable energy generated does not have to enter the main grid to be utilised. The main difficulty in the development
of distributed storage systems is related to the still high cost, but this problem can now be overcome in an original way.
example, it has been recently published for the first time that the cost of the Italian electricity market on the energy market
during peak hours has reached zero - no one needed to buy electricity – renewables supplied all demand. This means that there may
be a "new business model" for those who can "move energy in time and space." A key element will be small storage systems.
An ongoing research programme at the University of Cagliari, has shown that the problem can be overcome both locally (smart grids,
virtual power plant) and on regional scales (Sardinia) through an integrated and intelligent use of electric cars (as mobile small
storage systems) and dedicated fixed storage systems.
An intelligent battery fleet management can make renewable energy sources that were "not programmable" now programmable.
The objective is to make production error estimates less than 3%. This must be based on the forecasts of weather conditions for 48
hours and programming of the storage system. This would permit, on the day prior to generation, the shape of the production to be
known and this would enable improved management of the market and avoid the inefficient actions of dumping power or paying excessive
prices. This would achieve high levels of usage from RES production. The study analyzed the system behaviour in Sardinia with the
current schedule from RES by 2020 (45% penetration of RES in electricity consumption per year) and estimated the cuts achievable
with battery power up to 200 MW and installed capacity of 2400 MWh.
The results showed that this system would allow a level of 96% of the potential capacity of renewable energy currently installed
to be utilized. The most interesting result is that the peak battery capacity needed to obtain these results is not very big. The
scenario fpr Sardinia 2020 would be achieved with only 600 MW of capacity and 50 MW of batteries.
On the basis of the developed models it can therefore be concluded that the penetration of RES, if properly managed and integrated
with electrochemical storage systems, can ensure penetration of RES at an even higher level than those analyzed.
Now to energy independence!