Nowadays electricity generation through renewable energy sources, like solar, wind, small hydro, CHP (RES) is continuously rising due to a number of key socio-economic factors:
- The increasing social pressure on the national governments and utility operators towards a more sustainable environment, measured by the reduction of greenhouse gases emissions (GHG) due to the energy generation.
- With the adoption of Directive 2009/28/CE, the EU is putting in place an ambitious energy policy aimed to dramatically increase the amount of renewable energy (solar, wind, biomass, geothermal, hydro-electric and tidal) to cover the European energy demand, in a bid to spark a new industrial revolution that will deliver a low-carbon economy, whilst making the energy we do consume more secure, competitive and sustainable.
- The increasing energy demand at overall level, driven by developing countries, like China, India, Brasil.
- The expected achievement in 2020-2030 of the peak of the carbon fossil energy sources stocks which could be extracted and made available as primary energy sources at reasonable costs.
- The high costs and the strong regulatory concerns in the construction of new transmission lines to accommodate the overall rising energy demand at worldwide level.
- The transition from a centralized and centrally-controlled energy value chain to a more democratic and distributed energy generation, enabled by the disruptive innovation conveyed by the last generation of ICTs and Internet massive spreading, which is making it possible to each energy consumer to self-produce and accommodate (at least partially) its energy demand (energy prosumers), with a clear advantage of energy production at point-of-need and subsequent more efficient energy value chain due to lower energy losses in comparison with the traditional centralized energy generation and transmission value chain.
Unfortunately, despite the overall above depicted framework is largely pushing the renewable energy sources massive penetration, however there are a lot of significant yet unresolved challenges in order to successfully and effectively integrate high shares of renewable energy sources in the current energy production-transmission-distribution value chain.
In particular the higher electricity generation potential from renewable sources comes from wind and sun, which are inherently intermittent and, as a consequence, large amounts of variable generation from renewable sources are not fully forecast able and the overall power they can produce is continuously variable and fluctuating.
Intermittent generation like wind can cause problems in power grids, in physical balances and in quality of power, and can ultimately cause energy outages and security problems to humans and things.
This of course pose serious reliability and security problems to the stability and security of the actual grid, not to mention the quality of the energy produced.
Indeed current Power Distribution Grids are simple systems with very limited active control. The growing presence of Distributed Generation and in particular the introduction of renewable sources is expected to significantly change the scenario.
This new infrastructure, briefly called Smart Grid, presents an interleaved connection of power, control and communication.
As a consequence unfortunately these sources cannot be easily dispatched within the present distribution system since this was designed to operate in a "passive" way only.
Thus the increasing amount of renewable sources connected to the distribution network makes it more and more difficult to meet the stringent power quality and reliability targets that electricity consumers demand nowadays.
Energy storage is one of the most promising solutions to support the increased usage at the point of need of intermittent RESs, alleviating congestions and transmission losses in transferring electricity far away for the production site, as well as introduce other benefits related to the back-up (or buffer) action of Energy Storage Systems enabling:
- To capture surplus renewable energy, that cannot be utilized by the grid due to low load demand or transmission constraints
- To maximize the payback of the installed intermittent RESs (wind and solar generators) and reducing the cost of the electricity produced
- To provide supplementary or backup power in correspondence of RES reduction or absence;
- To effectively alleviate power quality issues (e.g. interferences arising from the connection of wind turbines to the grid), thus improving the electrical quality of the RES power output.
Hydrogen is undoubtedly a high-promising storage technology due to its high energy density and high reversibility, but it currently faces security and cost problems preventing it to be largely exploited into the energy storage market. Metal hydrides provide a much higher volume density than compressed or liquid gas. In particular magnesium hydrides (MgH2) have been selected for mass storage with clear advantages in terms of safety, stability, modularity, high density, high dynamic and reversibility.
INGRID project aims at achieving the following targets: Round-trip Efficiency (up to 50-60%), Energy Density up to 600 kWh/m3.