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Due to lack of accurate predicting methods, the power system balancing requirements have to be met in real time. On the transmission level in Nordic countries the usually abundant hydro reserves together with large scale Combined Heat and Power (CHP) share in the production mix are used to balance the grid. The useful feature in CHP is the ability to control the proportions of heat and electricity outputs and so balance the grid. The excessive energy can be guided to the district heating system or to a separate heat sink. (Aalto et al. 2012)

Hydro power and CHP are not in the same scale present in the Central or Southern Europe. There are also many ways of making the most of the energy infrastructure. Un- derstanding of the whole system is needed in order to create sustainable solutions and minimize overlaps and inefficiencies in energy infrastructure planning.

One of the most interesting near future solutions for grid balancing is storing energy. At present time, none of the storing technologies are truly viable in terms of large scale electricity storing. Still there are single cases where these solutions can prove them- selves helpful in grid balancing or local energy storing.

Countries such as Italy and Germany are pushing incentives for storing technolo- gies: Germany mostly in small scale and Italy mainly in grid scale. When these technol- ogies start to increase their penetration via subsidies fast development can be expected. Next the (subjectively seen) most promising technologies for grid balancing are intro- duced. The listing includes the technologies brought up in the interviews that are de- scribed in the chapter 5.

Battery systems are presently developed for both grid scale balancing and for LV prosumer appliances. Italian and German grids are both getting storing solutions imple- mented in the near future.

In Germany the government is starting to push for the small size batteries for prosumers in order to lower their price and increase their penetration in the German grid, increasing the maximum PV capacity that the grid is able to cope with. An addi- tional benefit to the prosumer is being able to further increase the share of self generated electricity. (Parkinson 2013)

Just recently a Japanese chemical company announced that it is capable of cutting down 60% of the present EV battery cost down to about 212 €/kWh while increasing the battery capacity in order to lift the operating radius of EV to 600 kilometers, more or less the radius of a common combustion engine driven car. Mass production of this so- lution, based on organic polymer electrolyte materials, could start in 2015. (Electric Vehicle News 2013) Such improvements affect also viability of other grid storage solu- tions besides EVs by bringing more advanced technology eventually to the markets.

Pumped hydropower storages are an old and reliable way of energy storing. The idea is to pump water from lower to a higher level and let the pumped reserve run through a turbine when electricity is needed. The limiting factors for the usage of this technology are the lack of usable spots for such a technology, the environmental aspects

such as effects of building dams and the economic viability of the projects (Gimeno- Gutiérrez & Lacal-Arántegui 2013). Still there is an interesting amount of capacity to be implemented. According to (EU 2013) the realizable potential for pumped hydro could be in the order of 3.5 times the existing capacity with the largest potential lying in Spain and Norway.

Large scale CHP covered a total of 21 % of the electricity generation in Finland in 2012. The Finnish Energy Industries association evaluates that the effect of increased wind power will affect most the operation of the numerous CHP plants in Finland. These plants can change the balance between generated electricity and heat produced. The report of the association especially underlines the importance of such measures at the early stage of the wind power implementation. (Aalto et al. 2012) In Germany and Italy there is potential for CHP balancing as well since their shares in CHP are in the order of 10-15% the fuel mostly used in Germany and Italy is natural gas. (EEA 2012) The output of gas power plants is fast to control.

Small or micro –scale CHP is one of the promising new technologies for distributed electricity and heat production. The fuel can be e.g. locally produced biogas or natural gas. The method of energy production can be e.g. micro turbines or a small combustion engine. Both of these example methods also have a corresponding solution in the indus- trial scale. The plant could function as balancing power while supplying the heat de- mand of a hotel or similar customer with a need for a large heat sink.

The viability of a micro-CHP plant in the electricity markets is hard to evaluate and depends mainly of the fuel price. According to the source a system of small scale CHP plants could be viable in the utility perspective in the liberalized electricity markets due to CHP’s operation as balancing power and the ability to produce heat in times of low electricity prices. The future electricity market prices however are hard to predict as stated in the chapter 3.3. The negative effect of presently low electricity prices and low heat demand on profitability, which exists during the summertime, could be partly cov- ered by using a combined cooling, heat and power (CCHP) system. (Kallio 2012)

Power to Gas (P2G) -concept’s purpose is to gain benefit of the times when electric- ity prices are low. In the technology perspective the concept relies on the traditional chemical way of storing energy, but with a concept different from batteries. (Morris 2013) P2G uses electrolyser to split water-molecules with electric current. The hydro- gen and oxygen are the output of the reaction. The hydrogen that could itself be used as a fuel is then let to react with carbon dioxide to produce methane. While converting the hydrogen into methane, some energy capacity is lost. However the storage of methane is much easier than of hydrogen: Hydrogen has to be kept in about twice the pressure. Me- thane can be added to the conventional car fuel tank to some extent without problems or need for additional investments. Also the gas network can fully make use of the me- thane whereas only the order of 2 % share of H2 is supported by the gas utilizing appli-

ances. (Müller-Syring 2011; NREL 2009)

Power to biofuel refinement could be a viable concept in countries with low popula- tion density and large reserves of biomass. In Finland there has been discussion and

some projects in replacing coal with wood chips and forest residuals. The potential could be as much as 50 % of the 14 TWh of energy by using the latest technology of torrefied pellets or gasified wood. The energy density of wood chips or forest residuals is about eight times lower than that of coal. It’s possible to process the wood into a more energy dense form. Torrefied pellets have an energy density only about 26 % lower than coal. Due to low moisture level the torrefied pellet is as enduring to store as coal. (Hap- ponen 2012) Due to these properties the torrefication is an interesting technology for biomass utilization. The future of the technology however is uncertain and depends on the speculative additional investment support mechanisms as well as the market devel- opment.(Laukkanen 2013; Flyktman et al. 2011)

Other methods with lesser estimated significance also exist. These include flywheel storages, compressed air energy storages, capacitors and super capacitors as well as var- ious nonconventional battery technologies. (ESA 2008)