Professor says the nanogrid is the only salvation of our bulk electrical grid
As technical chair of the Photovoltaics Sector of Solar Power International (SPI) trade show , Dr. Rajendra Singh, D. Houser Banks Professor in the Holcombe Department of Electrical and Computer Engineering and the Department of Automotive Engineering, stressed the importance of nanogrids in his opening remark of the technical symposium. Dr. Singh is world-renowned expert on photovoltaics.
On April 17, 2014 he was honored by U.S. President Barack Obama as a White House “Champion of Change for Solar Deployment” for his leadership in advancing solar energy with photovoltaic (PV) technology. The SPI trade show was held from Sept.10-13, 2017 at Mandalay Bay Convention Center in Las Vegas and was attended by over 20,000 people from all over the world.
The following was submitted to this publication by Dr. Singh:
As is evident from the events of recent hurricanes and storms, our bulk grid infrastructure is antiquated, inefficient and costly to maintain, The fact that ultra-low-cost local power generation (photovoltaics ) and storage of power (batteries) are available, fundamental changes are required in our existing and new electricity infrastructure. There is also the issue of protection of the bulk grid from solar storms and man-made threat from high-altitude nuclear explosion by the enemy.
With advancements in technology and volume manufacturing, the cost of photovoltaics power generation has reached to as low as low 1.78 cents/kWh and represents the lowest cost of electric power generation on the planet Earth. Battery capital cost as low as $112/kWh has been reported by Audi, and the lithium battery cost reduction is following the pattern of photovoltaics module cost reduction. Similar to the Tesla Gigafactory, there are many gigawatt factories under construction by Chinese, South Korean and Japanese companies. Thus, very soon power storage cost of batteries will be lower than any other power storage technique.
Except for some inductive loads, today all our loads are direct current (DC) loads. The alternating current (AC) power distributed by the bulk grid is converted internally into DC power and feeds our laptops, smart phones, refrigerators, air conditioners, etc. Today, in the process of AC power generation, transmission and distribution we lose more than 30 percent power.
The concept of nanogrid involves, power generation, power storage, power sharing (two-way power transfer) and power use by an individual entity or a combination of entities. Nanogrid can be a single house, single factory or a combination of several homes of a subdivision or various shops of a single mall.
Power generated by photovoltaics is DC power. The batteries store DC power. Thus, the new electricity infrastructure should use DC power nanogrid based on PV and batteries. Currently, utilities use about 1.6 watt DC power to generate 1 AC watt power. Saving of wasted power will further reduce the capital cost of DC nanogrid as compared to AC nanogrid. For the new entities, maximum PV should be installed on the roof of a building and rest of the PV can be mounted on the ground of a new house, subdivision or a factory, etc. The electrification of the transportation sector (cars, buses, smart and large trucks, etc.) require DC power and PV- and battery-based nanogrid is the most effective answer to generate electric vehicle’s charging stations throughout the country. Nanogrids based on PV and batteries is also resilient against solar storms and high altitude nuclear explosion.
Each existing house or building should have maximum PV (constrained by the location and design of roof and surrounding buildings, trees, etc.) installed on the roof and the batteries must be charged every day to power the critical loads (lights and refrigerators and fan, etc. for a household) at least for a day. Due to the advancements of the low-cost power electronics when the grid is off, grid customers automatically will have critical power (e.g. patents on ventilation) for basic needs. The proposed concept is line with the market forces and has been implemented by at least one utility. Vermont’s Green Mountain Power has given PV modules and batteries to some customers, and they are off the bulk grid. In a recent news item, GM announced the death of gas and diesel based automobiles, and the future is all electric.
Providing resilient, reliable and sustainable electric power will have huge impact on the economic growth of our nation. Public policies at the federal level needs to be changed to accommodate the market forces driven by technological changes. Underdeveloped and developing economies can leapfrog by building new electricity infrastructure based on nanogrids.