Electrical Grid of the Future

The following is an update I posted on LinkedIn in February 2015

Infrastructure, Options, and Centralization

"Infrastructure" is a word we often hear from politicians when they  want to spend billions upon billions to engage in "economic stimulus"  and transportation projects which often result in little long-term  change for the better. Other areas of infrastructure such as  telecommunications, sewage treatment, and waste disposal are usually so  well managed that we forget all the work and technology which goes into  keeping them running problem free every day. The electrical grid holds a  unique position, being the most important yet the least important  infrastructure area we have; almost all of the others can't function  without electricity, yet it is more a luxury than necessity for human  survival.

I will start by stuffing my thumbs in the eyes of both those who  scoff at passive production (referred to by the misnomer of  "renewables") technologies, and those who assume the only future is one  without "Big Oil" and "fossil" fuels. If we are to move forward, all  technologies must be harnessed where their strengths and/or conveniences  make them the most suitable option. For example, a wind installation is  not the best-suited method for powering an aluminum smelter. A coal plant is not the wisest option to place in urban or suburban areas.

Our current system is one of centralization and economies of scale.  Power plants with capacities in the megawatts and gigawatts churn out  electric current, sending it over high voltage lines and stepping it  down to lower voltages before distribution to the consumer. This method  has been developed and tested over a century and has no major faults,  that is, until the weaknesses of the system are considered.

From the perspective of reliability and emergency management, the  strength of our electrical grid is also its weakness - centralization.  In times of catastrophe decentralization is key; however,  decentralization is also the way of the future. Power must be produced  as close as possible to the point where it is consumed; preferably at  the point of consumption. This can be as simple as employing  battery-backed photovoltaic (PV) to provide electricity for lighting and  non-critical systems, something which accounts for over 10% of  electricity consumption in the US. Decentralization is key, but how do  we implement it? 

Consumers Are Not Created Equal

We must consider three categories of consumer: industrial,  commercial and residential. Industrial consumers are those who require  large amounts of power and whose demand usually remains at a constant  level. Commercial consumers typically require medium amounts of power  but have cyclical demand. Finally, the demands of residential consumers  are cyclical and low power. We focus on residential consumers, as this  is the area where the most changes will occur, and many of these changes  also apply to the other consumer types.

Battery-backed PV, along with small generators or wind turbines,  will fulfill the power needs of most residential consumers. The day when  your "utility closet" becomes a true utility closet doesn't seem that  far off for those who are forward thinking. Implementations will vary  depending on power requirements and individual tastes, but tomorrow's  utility closet will house a battery bank, power inverters, grid-tie  equipment, a home's control system, and possibly a small  hydrocarbon-powered generator. A home's roof will turn from passive  structure into the home's primary power generator through the use of PV  systems. Some homeowners will also install small wind turbines in the  1-5kW range to supplement solar during inclement weather, while others  opt for a generator, or turbine and generator.

Industrial consumers will continue to rely on traditional central  production for primary power, often from hydrocarbon, hydroelectric, or  nuclear sources. Technologies such as blast furnace gas generators will  turn consumers into net power producers. Secondary power will come from  roof-mounted battery/PV systems. 

Commercial consumers will straddle both ends of the generation  spectrum. Larger consumers and those who require 100% uptime, such as  banks, will remain connected to traditional centralized sources. The  remainder will take an approach similar to that of residential  consumers. 

It Starts Outside the Wall Socket

There is a price to pay when converting electricity from AC to DC  and vice-versa. In battery and PV systems the penalty is often twofold:  the conversion of DC battery or PV current to AC line current, then back  to DC within devices such as computers. The solution is to manufacture  appliances which require only DC, and to implement and standardize DC  line voltages for use by those appliances. Voltage levels of 12, 24, and  48 volts DC are a good start; however, the beauty of the system is that  voltages and currents can be configured on-the-fly to suit the needs of  a particular device.

A home's power system must be capable of reliably forecasting the  maximum power requirements for both peak (current draw when loads such  as air conditioners are switched on) and average demand. All of this  must be accomplished while retaining the current electrical sockets and  AC line voltage capabilities.

How does all of this happen? Many appliances in the home already  contain microcontrollers, and it is a trivial matter to incorporate the  required power electronics and power-line communication (PLC)  capabilities into new devices. The process begins with the outlet and  line itself, where several options are available according to cost and  complexity. The simplest, from a wiring perspective, is similar to  current systems where all outlets on a circuit breaker share common  wiring. The next implementation has each plug on an outlet sharing  common wiring, while the final solution provides dedicated wiring for  each plug.

Moving away from the outlet and into the utility closet, we find  one or more power inverters. The most simple system has one inverter for  each set of line wiring in the home, while the most complex contains an  inverter for each plug. In addition to providing a default 120VAC, the  inverters are also capable of supplying the required DC line voltages.

Traditional "dumb appliances" don't communicate with the home's  power system at all, expecting a line voltage of 120VAC to be available.  Smart appliances will communicate their optimal voltage and current  parameters to the home's power system so it can tailor individual plugs,  outlets, or lines to fit the profile as well as operate more  efficiently. How this works is out of the scope of this post.

By making electrical devices and buildings utilize energy more  efficiently, we can reduce the amount of demand on the electrical grid  and decommission unneeded power production facilities. 

A Network of Grids or a Grid of Networks?

Nothing covered thus far is new, many homes and businesses have  made the partial or full switch to PV, but the real changes lie in the  grid itself and the way electrical devices interact with it. The role of  today's power companies will shift slightly away from power generation,  towards network management, maintenance, bidirectional metering, and  billing.

At the local level, the grid will resemble a computer network, each  consumer tied in to the "local area grid" (LAG) much like a microgrid. In this arrangement  consumers within the LAG are effectively isolated from those outside the  LAG. Power transfers between members of the LAG occur automatically.  Each member sends real-time power availability statistics to the LAG  controller. If one or more member's statistics go negative, the LAG will  gate power from members with excess capacity to compensate. For  example, at some point in time a home may require more power than its  systems are capable of delivering. A home's control system and grid-tie  equipment will sense this condition and send a power request to the LAG,  which will in-turn request power from homes which have advertised  excess capacity.

LAGs are connected to each other, and to larger individual  consumers, through primary area grids. PAGs see LAGs connected to them  as individual members rather than a grouping of consumers, and like  LAGs, allow transfer of power between PAG members. Higher levels of  distribution networks include subtransmission area and transmission area  grids, each functioning in a similar manner to a LAG.

A possibility which opens with LAGs is the ability of LAG members  to own the LAG to which they belong. For example, a LAG is built within a  new residential development. In this development a portion of the  homeowners' association (HOA) fees go towards contracting LAG operation and  maintenance to a third party, while the LAG is owned by the HOA. Those  who own LAGs can set the conditions under which power is permitted to  enter and exit their networks, taking into account things like times and  prices.

Each member of a LAG will have the option to set the price they are  willing to pay for power they request from the LAG, as well as the  price of power the supply to the LAG. Solar may be sold at a lower  price, while power generated from hydrocarbons may fetch a higher price.  Pricing also affects the import and export of power to and from LAGs.  For example, a member requests power and is willing to pay $0.12 / kWh  for. The lowest price within the member's LAG is $0.14 / kWh; however,  the LAG knows it can import power from the PAG for $0.12 / kWh  (including tolls and other fees). A request is issued to the LAG with  excess capacity, which in-turn requests power from the member selling it  for the target price. The requested power is placed on the source LAG,  travels through the PAG, and into the consumer LAG.

Building the electrical grid of the future is more than just  shifting to newer technologies and updating transmission systems, it is  changing our consumption habits and rethinking how buildings interact  with various forms of energy. We must act responsibly and care for our  surroundings while understanding that hydrocarbons are the most energy  dense and portable method of energy storage. True energy independence is  the refusal to rely on distant power production you have little or no  control over, regardless of how said power is produced.