Rapporteur: Michel Duguay 17 June 2019
In North America, as well as in Europe, the price of electricity from wind turbines and from photovoltaic panels is now low enough to compete with electricity produced by conventional power plants based on burning coal or natural gas. At least two problems, however, must be tackled in order to make renewable power large enough to alleviate the climate change issue. The first one is storage. The wind does not always blow with enough strength and the electrical output of solar panels fluctuates with cloud coverage. The second problem is the need to transmit electric power from power-rich regions to power-poor ones while at the same time maintaining grid power reliability and frequency stability.
The renewable power fluctuation problem is being alleviated by the recent development of high capacity batteries for electric cars and for buildings. The idea is that cars are parked during a good part of the day and that we could keep them connected to the electric power grid while parked. When the power grid has excess electricity it could store it in the electric car and building batteries. When the power grid faces a very high demand for electric power it could go and fetch electrical energy stored in the building and car batteries. Computers would be used to smoothly manage this exchange of electric power.Read more
The second problem has to do with the transmission of AC (alternating current) electric power. North America has five power grids which can only exchange electric power if the precise near-60-Hertz AC frequency is maintained independently in each one of the power grids. The five power grids are:
- the Western United States, British Columbia and Alberta;
- Eastern US, central Canada and the maritime provinces;
- Québec province;
- Texas; and
AC electric power can be smoothly exchanged between these regions if it is first converted to DC (direct current), transmitted over high voltage DC transmission lines (up to one million volts) and then reconverted to AC at a frequency that is synchronous with that of the receiving region. Another way for different regions to exchange electric power is by means of variable frequency transformers.
One additional technique to maintain power grid reliability and frequency stability is by introducing so-called demand side management. The idea is for the power company to control devices like hot water heaters and cold water refrigeration used for air-conditioning in large buildings. Domestic hot water need not be produced during peak demand hours. The same applies to cold water refrigeration used for air conditioning. Thanks to computers and Internet communications the power grid could turn these devices on or off depending on electric power availability.
Another important aspect of electric power grids is legislation governing the transmission and distribution of electric power from utilities to customers. In the US the Energy Policy Act of 1992 was passed and it required owners of high power transmission lines to permit access to electric power generation firms. The Energy Policy Act of 2005 introduced measures to encourage the production of renewable electric power.
Europe has become a world leader in terms of wind and solar power deployment. A broadly recognized goal is to achieve 100% renewable power generation in the present century. One theme being debated is distributed versus centralized electric power distribution. The EUROSOLAR organization is promoting decentralized generation and ownership whereas the DESERTEC organization envisions a highly centralized system of imports and exports of solar and wind energy throughout Europe. There is also a proposal to combine the two ideas in a smart Supergrid. The idea of increased investments in renewable energy R&D has broad support in Europe. See https://www.sciencedirect.com/science/article/pii/S0960148119302319