The Main Roadblocks to Renewable Electricity Development
There are currently a number of roadblocks to renewable electricity development, despite the fact that its share of total electricity production worldwide is expected to go up to 36% by 2035 (and it is still a conservative forecast!) and that its growth is estimated at twice that of the overall growth in electricity demand.
The main issue related to renewable electricity production relates to its intermittent and not entirely reliable production. While a nuclear power plant can operate on demand and almost continuously 80% of the time, a wind farm or a solar farm generally output to the electrical network 10-20% of the time. In addition, these rates are averaged, as renewable electricity production output can vary depending on the circumstances. Electricity supply is deemed a critical utility so any disruption is considered unacceptable. Electricity demand traditionally follows a “bell” curve, with a peak load between 6 and 10 pm, and production needs to equal consumption at any one time. Since renewable electricity depends heavily upon climatic conditions, production output cannot be guaranteed and balancing production and consumption is not possible. Specific climatic conditions can lead to an excess or a deficit of production output on the electrical network which can lead to network imbalances. With the current set of technologies, renewable energies can only be a contributor to the overall electricity mix and cannot replace conventional power plants, which can be regulated to balance the network out. Hydroelectricity is the only notable exception as its contribution can be regulated, even though hydroelectricity plants operate intermittently as “stock” needs to be rebuilt on a regular basis. Outside of hydroelectricity, the current penetration rate of renewable energy is around 5% in average. The penetration rate may vary depending on the particular situation of the networks as well as the specific electricity production mix. In Denmark or Germany, the penetration ratio is higher, the effects of variability of production being compensated by coal thermal power plants (very polluting) and interconnections to the European transmission network. In France, the rate remains low as 78% of the current electricity production is of nuclear origin. Nuclear power is indeed very stable but not flexible. The share of nuclear power production thus prevents the overall system from accommodating more than a certain volume of intermittent, as it cannot provide the flexibility required (Durand 2007). Most experts think this rate can easily increase around 10-15% without significant impact on the network. Above this level of penetration, the penetration of renewable energies leads to important restructuring of conventional generation and to the setup of necessary flexibility mechanisms. It is generally admitted that the network stability can still be managed up to 40% of renewable penetration, but higher ratios are today unknown. The current growth of renewable production output therefore raises many questions and issues on how to manage the electrical network. Possible disruptions are however on the verge to occur. They could reshape completely the electricity market landscape. They will be looked at in the Chap. 5.
Other Perspectives for Renewable Energy
Besides electricity production, renewable energy can be used to produce heat. Actually, heat generation was historically the first use of renewable energy— biomass (wood, waste, etc.) is the oldest way of heating up a space.
According to the International Energy Agency (2012), about 1000 Mtoe of biomass was used for heat generation in 2010. The vast majority of it (77%) was related to a traditional use of energy (individual heating, lighting, cooking).
Renewable energy is very interesting for heat generation, whether it is space or water heating. Heat can be stored to a certain extent, making renewable energy (geothermal, solar) very suitable for heating systems. The use of renewable energy for heat production could thus have a significant impact on fossil resources consumption (© OECD/IEA, Heating 2014).