When a consumer becomes a net producer of electricity
The UN report ‘The World Population Situation in 2014’ puts the world’s population at 7.2 billion in 2014 and is expected to increase by more than 2 billion by 2050. The same report also states that ‘more than half of the world’s population now lives in urban areas’.
The report concludes that ‘the continuation and consequences of these population trends will present both opportunities and challenges for the formulation and implementation of the United Nations’ post-2015 development agenda and for the achievement of all internationally agreed development goals’.
Obviously, one of the opportunities is high demand for electricity and energy-related skills. Similarly, one major challenge expected from this population trend is meeting the high energy demand through activities that are sustainable and harmless to the environment.
The report is particularly exciting since it clearly states that more and more people will dwell in cities by 2050, putting more pressure on available power and energy infrastructure.
The 21st century has witnessed the highest human appetite for power and energy, specifically electric power. This is partly driven by the fact that electricity is the finest of all matter. One of the characteristics of electricity is that its demand does not reduce or stagnate with time, even if there is no net growth in human population.
There is no doubt that human appetite for electricity is on the increase in almost all sectors of human socio-economy. Electricity is synonymous to farm produce and requisite activities must be carried out before sowing and harvesting. The quality of harvest is determined by the quality of seedling and other variables.
Electricity must be generated before it is distributed. Transmission is a link between the generating systems and the distribution systems. Transmission is therefore unnecessary if generation is done at the point of consumption, that is, at the distribution level. This leads to the concept of distributed generation (DG).
Transmission network is synonymous to the transportation network in the farming scenario. In power systems, transmission is used only when energy is generated at a location remote from human dwellings (called load centres) and usually for bulk power transfer.
Bulk power generating systems are sited far from human habitats for reasons such as the harmful nature of their activities in the case of large hydro, the need for large storage, and the proximity of raw materials such as in the case of coal-fired power plants.
Distributed generation involves generating energy at the distribution level where energy consumers reside. Because DG involves siting generators close to human habitats, it uses generators that are harmless (or friendly) to the environment when in service. Such generators include solar energy systems (solar PV and solar thermal), wind turbine electric, micro hydro generators, and diesel and petrol generators.
All of the above generators (except diesel and petrol generators) are called distributed energy resources (also called renewable energy resources). In a nutshell, distributed generation is often based on renewable energy resources.
In recent years, penetration of renewable energy resources has been increasing due to a number of drivers such as environmental issues, government’s green incentives, increased off-grid (rural) electrification, rising energy tariffs, and rising human appetite for transportation electrification such as Vehicle-to-Grid (V2G) or Grid-to-Vehicle (G2V).
This increase in distributed generation using renewables comes with new challenges. Such is the problem it poses to control and protective devices on the existing distribution grid. Typically, the V2G and G2V operation of the distribution grid entails bidirectional flow of power, a departure from well-established unidirectional flow of power, resulting in blinding and false tripping of protective relays.
The benefits availed by distributed generation are enormous and outmatch the challenges it presents, if engineers can provide solutions to the challenges. A feasible model is the recently-advocated microgrid concept which supports the use of DG with bidirectional power flow primarily to meet local consumer demand.
One major benefit of DG is its elimination of transmission power losses since it involves generation and distribution of power without the transmission link, where huge power losses take place.
Imagine if half of the cars in Miri city were to be electric in G2V (grid supplying vehicle) mode, the current distribution system will likely collapse due to voltage drop and frequency oscillation! One feasible way to connect these cars without major upgrade to the power grid is to distribute and supply the cars at various households where power is generated using microgrid.
This way, each consumer’s premise generates sufficient power using the microgrid (hybrid of wind and solar). Since these energy resources are intermittent, the system generates and stores its excess whenever generation exceeds demand. During ebb demand, the consumer exports power to the grid; during peak demand, the consumer imports power from the grid. In this system, there is a potential for a consumer to become a net producer of electrical energy.
Of course, renewable energy systems require high initial capital investment at the moment because their use is not widespread. Since human appetite for electrical energy is ever increasing, it is only a matter of time for electric vehicles, electric motorcycles, electric ships, and all-electric military and commercial aircraft to become common place (drones and other autonomous aerial vehicles are all-electric from inception).
A Chinese drone firm recently revealed the first ‘personal autonomous aerial vehicle that allows flights over medium distances’. When the ‘big bird’ inevitably becomes all-electric, the human race will probably be confronted with a new scale of demand for electrical energy.
With new technologies, it is possible to harvest more than sufficient electrical energy (and possibly store the excess) from lightning while aircrafts are airborne.
Would it be better to harvest electrical energy 40,000 feet above the earth’s surface and store it for usage by ground stations? Whether it would happen soon, only time can tell. However, it is the hope of the author that all-electric commercial aircraft would harvest electrical energy in this way in his lifetime!
Aminu A. Maruf is a postgraduate student at the Faculty of Engineering and Science, Curtin Sarawak. He can be contacted by email to firstname.lastname@example.org.