II. Smart Grids, Supergrids, Ecogrids and Hypergrids
(originally published 4/15/2007)
In my previous post on the electron economy, I discussed the desirability of building out the electricity-based energy system as a means of harnessing most renewable and carbon-neutral forms of energy. Following Ulf Bossel’s analysis of the energy efficiencies of different energy delivery and conversion systems, we have determined that electricity generation, efficient forms of electric storage (electrochemical batteries and beyond), and electric motors, powered by renewable energy flows, should become even more central in our energy economy, much more important in the short and intermediate term than more celebrated biofuels or hydrogen fuel cells.
As we already depend on electricity for so many of our stationary power needs, the creation of an electron economy at this point in time means in practice converting where feasible and efficient, transport and heating applications to the use of energy from electricity, which now or eventually can be supplied renewably. There is a environmental “double pay-off” for building an electron economy: the efficiency of electricity and electric motors applied judiciously reduces overall energy demand while opening the door to multiple means of harnessing renewable sources of energy such as wind and solar now and in the not too distant future. In the next of this sequence of posts I will address some of the primary technological hurdles in creating a workable electron economy powered by clean energy. Finally I will discuss the marketing and political challenges in realizing the transition to an electron economy.
Energy Infrastructure: the Electric Grid
In order for the electron economy to emerge as the primary (but not the only) clean energy delivery system for our power-hungry advanced and developing societies, our electricity transmission system will have to grow in capacity and sophistication. If we are serious about shifting the work of transport and heating to electricity, even with the efficiency gains of electric motors and modern transmission methods, this means that multiple gigawatt-equivalents of energy will be transferred from gas pipelines and supertankers to electric transmission lines. Advocates of electric automobiles point out that some of the nighttime baseline transmission of electricity is wasted and can therefore be used to charge battery electric vehicles at night without increasing the supply of electric power. Still, if most transport devices are plugging into the grid at nighttime and some during the day, demand will eventually go up. Furthermore, we will want to operate a securer and more reliable transmission system than currently obtains, as even more vital services will depend on the electric grid for power.
The electric grid in most advanced industrial economies is usually extremely reliable but there are always events that expose its vulnerability. Massive blackouts and power failures occur every few years for reasons beyond expectable weather events. When grid failures occur, there are the usual calls in the media for updating “our aging electric grid” or the like, calls which too often disappear from public view when the crisis has past. Furthermore, if our expectation is that global warming will bring more extreme weather, the electric transmission system should be built in such a way as to become more weather proof. One key to building a sustainable, greener society is to create an advanced electric grid with sophisticated technology, some of which has yet to be invented. To do so, we will need more sustained public and political attention to and public and private investment in the power grid to build a cleaner energy economy that works as we have come to hope and expect.
The Smart Grid
For a number of years now, analysts of the electric grid have hailed the introduction of a so-called “Smart Grid” that utilizes ever cheaper computing power and advanced telecommunications to better manage the power grid. Sometimes called the replacement of electro-mechanical systems to manage power with fully automated, digital controls and analytic tools, the Smart Grid has been hailed many times and has been partially implemented in different areas of the world. When power grids go out or perform below expectations, the hope is that advanced information technologies would have prevented or minimized the failure.
One of the challenges of the power grid, essentially a huge and complex electrical circuit, is that it is a tightly-coupled system that is prone to cascading system failure, failure of one part of the system leading with very high probability to a failure of the next. The paradigm case of this type of failure was the blackout in the Eastern US and Canada in 2003 where 50 million people lost power due to a cascading failure of the power grid. In the same year in Italy, a blackout of similar proportions was caused by weather effects on transmission wires. Advocates of the smart grid believe that smart grid controls could have minimized the breadth and duration of such a cascade by the use of automated controls as well as better and quicker system status information for system operators.
According to David Moore, a supplier of utility system controls, in Smart Grid News, the smart grid has the following essential pieces:
1) Intelligent customer metering with telemetry, allowing for instantaneous usage statistics and no need to physically read meters.
2) Distribution and outage management with grid self-healing capacity
3) Automate distribution operations and substations
4) Simulation and optimization tools that allow for strategic system and resource management
5) Enterprise Business Management tools that allow for a system operator to optimize its business decisions and enhance overall system performance.
Others emphasize that without a smart grid, distributed power generation and renewables are not so easily integrated into the power grid. Still the smart grid does not pre-suppose the use of distributed power or renewables; it is just the introduction of next generation grid technology in an appropriate and forward-looking way.
Beyond the more established smart grid concept, the notion of a supergrid has been circulating in power system management and renewable energy circles. The supergrid would allow for electric generation resources to be pooled on a continental and international basis, allowing more intermittent and periodic renewable energy resources to balance each other out, reducing the need for fossil fuel or nuclear baseline power generation. The term “Supergrid” has been applied to both a specific long-distance electric transmission technology, i.e. the use of superconducting transmission lines, and more generally to the build-out of intersystem and cross-national linkages in electric transmission systems.
The heart of the supergrid concept refers to efforts to build-out and manage inter-system and cross-national electricity transmission facilities of any nature, whether conventional or super-conducting. A typical argument for the supergrid is as follows: the Plains states, especially the Dakotas have abundant wind energy, the US Southwest has abundant sunshine during the day and the coasts have constant and periodic tidal energy as well as wind resources. The European and North African example would link the wind resources of Northern Europe with the solar resources of the Mediterranean and the Sahara. Continental supergrids would allow for the intelligent integration of these resources so as to maximize the use of natural energy flows and balance out some or perhaps all of the intermittent nature of many renewable resources.
In the US, the supergrid term often refers to the use of superconducting electricity transmission lines to reduce resistive losses for long-distance transmission of electricity, which in turn would support the mission of balancing resources over long distances. Without superconductors, it has been estimated that high voltage DC could theoretically be used for transmission distances of up to 4000 miles, though a superconducting transmission line would reduce the losses for that trip. Superconductors are metals or other compounds that offer extremely low resistance to electricity at very low temperatures. In 2001 Chauncey Starr, founder of the Electric Power Research Institute, applied the term Supergrid to a super-cooled buried pipeline for electricity. Starr proposed that liquid hydrogen could be used as a coolant for the superconducting electric transmission line and the hydrogen coolant could be used in addition as a fuel.
By piggybacking the notion of a superconducting transmission line onto the energetically inefficient process of isolating and compressing hydrogen gas, the waters have been muddied a little as improving the efficiency of electric transmission and hydrogen’s energy balance as a fuel are unrelated technical and economic issues. If appropriate superconductors are found, it may very well be more efficient to use liquid nitrogen as a coolant even though nitrogen does not foreseeably have a usage as a fuel. As I have stated elsewhere, in a (fairly distant) future regime of superabundant renewable power, hydrogen may have storage and load balancing benefits but in a regime of scarcer renewable energy, it seems like a waste of valuable power (75% losses) to isolate and store hydrogen. The net efficiency of a superconducting transmission line whatever the coolant, needs to be proven before they are practically applied: energy to refrigerate and maintain the line would need to be substantially less than resistive losses on a conventional high voltage AC or DC transmission line.
The supergrid with enhanced conventional high voltage transmission or superconductors would need a consortium of electricity transmission providers or system managers to, at least partially, increase the interoperability of their systems and create the basis for a more highly integrated international electric power marketplace. Among the pieces of information that could be traded upon in that marketplace would be overall emissions, energy efficiency, and carbon intensity, depending in part on the regional, national or international costs associated with those environmental factors. To manage a supergrid that harnesses multiple renewable energy sources, local and regional weather data would need to be integrated into the already complex business of managing a power transmission system. We should see more academic and real-world cooperation between power engineering and earth science, specifically meteorology, as management of the supergrid will depend on such diverse data types and sources.
Many advocates of sustainable development emphasize the importance of local resources, so I’ll introduce here the concept of an “Ecotopian Grid”, shortened to “Eco-grid” or “topo-grid” using the Greek word “topos” for place. The Eco-grid is a theoretical outcome of the evolution of electric transmission based on the “Ecotopian” ideal of the use of local resources against centrally managed or imported goods and resources. Renewable sources of electricity such as photovoltaic cells or wind turbines can be applied effectively on a smaller scale and can therefore fit the “small is beautiful” ideal. The word “topogrid” is more technical sounding but I believe more accurate as I do not know whether this arrangement would actually be more ecologically sustainable than a larger scale electric transmission system.
While the logical extreme of “small is beautiful” is to live “off-grid”, everyone does not share the ideal of self-sufficiency nor is it economically feasible or technologically practical for most people or many localities. The eco-grid is an intermediate step where a locality or region would focus on developing its local renewable generation and power storage potential. The eco-grid would capitalize on the efficiencies of shorter distance transmission and relative insulation from distant power outages.
With the development of efficient, small-scale renewable generation, cost-effective small-scale power storage, and sufficient natural energy flux in a locality, the eco-grid would be an option. As historically power grids have tended to expand in their scope to meet demand, the eco-grid may however not be able to fulfill power demand or achieve the efficiencies of the supergrid or central power generation facilities. Issues of reliability and big question marks surrounding effective and cost-effective power storage make the eco-grid at the moment just one theoretical end point for the evolution of electric transmission systems.
Beyond the obvious, necessary upgrades in electricity transmission infrastructure that fall under the “smart grid” rubric, there seem then to be two opposing directions in which the development of electricity transmission resources could be built: one that concentrates on small scale, local development while another that builds larger scale vertically-integrated structures that enable inter-regional and international cooperation. Some will probably decide this conundrum by reference to prior philosophical commitments or personal values: “small is beautiful” advocates will prefer a topogrid, while technological optimists will focus on building a supergrid. Best would be if the evolution of electric transmission systems would be directed by the practical net effects on system users and the environment of one arrangement over the other.
I am positing that there exists in theory if not practice a subset of supergrids that could be called a hypergrid. Modeled on the upstart progeny of the electric grids of the world, the Internet, the hypergrid would be governed by a continental, hemispheric or global ruling body that determines rules and protocols for transmission and electricity generation but leaves the management of the grid to member organizations. Within the confines of network protocols, which would allow for disconnection and re-connection to the main supergrid, a hypergrid will have a cellular structure that allows for relative local independence from distant power generation and transmission facilities. It is a “hyper” grid because it is large and multidimensional, containing perhaps more aspects than can be represented at a central control dashboard or center. The micro-level fluctuations upon which local generation of renewable energy will depend may introduce too much complexity into a continent-spanning, vertically integrated system, so a hypergrid must be designed with higher tolerances for natural fluctuations in energy and current.
What does the notion of a hypergrid add to the established supergrid concept? A supergrid would be centrally managed and planned while a hypergrid would contain a collection of managing agencies for different “levels” of the grid. At the heart of a hypergrid there might be one or more supergrids, with vertically integrated management for that portion of the grid. Similarly the Internet thrives in part because of management of “Internet backbones” by government and large corporations that are the trunk lines for a vast majority of traffic on the network. While a supergrid is a plannable entity, a hypergrid cannot be entirely planned or overseen thus leading to some inefficiencies and uncertainties. On the other hand, a hypergrid would theoretically be less prone to cascading system failure or attack as there are multiple trunk lines and levels to the network. Supergrids could co-exist at different levels with topogrids within a hypergrid structure.
Most importantly, the hypergrid would allow for all types of carbon-neutral and carbon-negative types of energy generation to compete with each other, no matter what their scale, on which is the most effective in environmental and economic terms. With appropriate taxation or emissions caps on harmful effects of generation and transmission, local and large-scale generation of renewable energy could find their relative strengths and weaknesses as technology develops and matures. Under a regime of emission-sensitive regulation, the hypergrid might create an efficient and sustainable market mechanism for power generation and transmission, allowing the more sustainable solutions to flourish.
In the next posts on the electron economy I will survey the technological issues of electric storage, transport options and all-electric buildings.