Lovell, A. (2019). Direct Current Microgrids: The Wave of the Future? Solutions 10(1): 14–17. https://www.thesolutionsjournal.com/article/direct-current-microgrids-the-wave-of-the-future
Idea Lab Noteworthy Direct Current Microgrids: The Wave of the Future? by Ashley Lovell, Ph.D.
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hat happens when you combine an aging electrical grid with the increased resilience demands of rapid climate change? You get longer, more destructive power outages. Our continued reliance on fossil fuel and long-distance energy transport for energy production and the power outages associated with our aging grid are putting our health, our economy, and our national security at risk. NASA and NOAA agree that the years 2014, 2015, and 2016 each set new all-time temperature records in a stepwise fashion.1 As our global air temperature warms, so do our oceans, leading to stronger, more frequent and more destructive storms.
The Climate Crisis and Our Aging Energy Infrastructure 2017 was a year of record-breaking natural disasters in the United States, including a trio of hurricanes (Harvey, Mariah, and Irma) with damages over USD$200 billion.2 The residents of Puerto Rico were largely without power for over six months after hurricanes Mariah and Irma hit in November of 2017. Recent reports3 argue that the storms themselves, combined with the devastation to the island’s energy infrastructure, resulted in over 4,000 casualties. Natural disasters like the hurricanes that pummeled Puerto Rico highlight the risks, inefficiencies and correlations between our changing climate and our aging energy infrastructure. Our current energy infrastructure is increasingly unstable and underfunded. With more than 640,000 miles
Photo courtesy of The Alliance Center
Flow diagram showing solar-fed DC current system at The Alliance Center
of high-voltage transmission lines in the lower 48 states aging out of their 50-year life expectancy, funding gaps in electric generation, transmission and distribution are projected to grow to a level of USD$107 billion by 2020.4 From the 1950s to the 1980s significant power outages in the United States averaged fewer than five per year.5 In 2011, there were over 300 significant power outages on the grid. Furthermore, while 40 percent4 of new power generation came from natural gas and renewable energy in 2015, our antiquated electrical grid is currently incapable of absorbing all of the energy produced by renewables, meaning a substantial amount of potential renewable power—power that we are capable of producing—cannot be used. What does this mean for our energy security? It means that we can expect longer and more frequent power outages across the country, and that without significant investment, much of the energy generated by that could be produced from renewable sources will be lost because of inefficiencies in the current grid.
14 | Solutions | January 2019 | www.thesolutionsjournal.com
Eliminating the Middleman: Direct Current Microgrids The current electrical grid in the United States was instituted at the turn of the 20th century. The grid was developed to deliver alternating current (AC). AC has long been the preferred method of energy transfer as it can be easily transmitted over hundreds of miles. The nation-wide electrical grid operates on AC, which requires inefficient conversions to power modern technologies that operate on direct current (DC). Technologies such as solar panels, computers, cell phones and modern LED lights all operate on DC. As such, we must convert the energy that comes from the AC grid into DC voltage for those devices to function—resulting in at least five to ten percent energy lost6 during conversion. The United States Department of Energy’s Power America initiative predicts that by the year 2030 an estimated 80 percent7 of all US electricity will require conversion from AC to DC, which creates the potential for significant energy savings if conversion can be reduced.