Unprecedented wildfires in California. 1,000-year flood events happening on what seems like an annual basis. Massive polar vortexes bringing bone-chilling cold. With climate change evolving from a distant danger that people hear about on the news to something that effects their daily lives, there is increasing interest in renewable energy sources.
While solar has conquered suburban subdivisions across the United States over the last decade, people tend to be much less familiar with other renewables, particularly as they relate to where power to their homes comes from. Thankfully, while the thread of climate change is real and omnipresent, our energy grid is increasingly shifting towards renewable sources.
What is renewable energy?
In better understanding renewable energy as it pertains to the grid, it is important to first understand what exactly constitutes a renewable. According to the US Energy Information Administration, renewable energy sources are those that are “naturally replenishing but flow-limited.” Essentially, these sources represent finite potential energy in any moment in time but are inexhaustible over a longer period. Under this definition, potential renewable energy sources include solar, hydroelectric, wind, geothermal, and biomass. Essentially, the earth replenishes renewable energy sources on a human-scale timeline of days, years, and decades, whereas carbon-based fuels are produced on a geologic timeline measuring in the millions of years.
In human terms, renewable energy sources also represent a return to our energy roots. Energy from the sun is what makes life possible, and humans have harnessed its power to warm homes and dry food for millennia. The origins of water power are hazy, but historians date the use of the first water wheels back approximately 2,000 years, and it has played a crucial part in the grid since the first hydroelectric power plant was constructed at Niagara Falls in 1879. Widespread use of windmills dates back approximately 1,000 years, having been used to move water for irrigation and break down hard kernels of grain into flour for bread. The use of the earth’s geothermal energy is also quite ancient, with evidence of paleolithic humans warming themselves in geothermal baths, and later Chinese and Roman bathhouses situated to take advantage of hot springs. Biomass-fed fire, meanwhile, represents the first energy source humans truly harnessed.
Needless to say, renewables have evolved significantly from their respective original forms to represent sizable and growing grid energy sources. Home solar installations have become omnipresent throughout the United States, growth driven by a combination of technology improvements and government incentives, allowing for home owners to lower their own energy bills while feeding sun-powered electricity back into the grid. The energy independence afforded by home solar, offering every home the chance to be its own miniature power plant, would have been a radical concept just a few decades ago. Moreover, residential solar represents a consistent source of clean power for utility companies seeking to meet renewable energy mandates while planning for a more resilient future.
Beyond home solar, large scale solar energy projects, often dubbed solar farms, have been initiated and brought online by major grid energy suppliers. China’s arid Inner Mongolia region currently plays host to the world’s largest solar farm, roughly ten times the size of Central Park at 43 km2 and with enough generation power to light 1.5 million homes. Closer to home, California’s Solar Star represents the largest solar project in the United States at 559 megwatts, narrowly edging out two other California solar projects that each clock in at 550 megawatts. Speaking to the technology’s maturity, Disney recently completed a 50 megawatt project in Florida, enough to power two of its theme parks. With projects like these having proven solar energy’s ability to scale, we can expect to see its share of grid power increase in the coming years.
As noted, hydroelectric represented one of the first large scale sources of electricity in the United States. Hydropower differs significantly from solar in that its effectiveness is limited at a smaller scale. Hydro projects represent massive capital investments, and the dams resulting from them can often be disruptive to communities situated near water sources. As such, these are massive, complex, challenging projects that often take decades to see through completion. More importantly, most major water sources in the United States, particularly on the East Coast, have already been dammed, meaning that building more dams does not represent a simple renewable solution to our climate woes. Hydropower also faces environmental concerns in its own right, as its utilization often requires the damming of rivers, altering local environments and preventing riparian migrations of fish and other animals. The challenges associated with hydropower mean that it does not represent a panacea to our emissions woes.
Hydropower’s major advantage is that water never stops running. This stands in contrast to solar and wind, where cloudy skies and still air result in reduced energy production. Constancy in production of electricity is critically important to meeting baseload needs, baseload being the electricity needed to meet the grid’s needs at times of minimal usage. Solar and wind are not ideal sources for baseload power, given their intermittent nature, as there might be a time when it is either not sunny – nighttime – or not windy, and production drops. Water, however, runs all the time, making hydropower the ideal renewable source for meeting our baseline needs.
Despite humans having harnessed wind power more than a millennium ago, widespread use of wind for electricity generation at scale is a relatively new development. Nonetheless, wind played an often overlooked but crucial role in supplying electricity to rural areas prior to the extension of the modern grid, providing the only source of electricity for many remote North American farms. Though windmill use for historic uses, namely to pump water, remained common throughout the 20th century, it was only in the later decades of the 1900s that global interest in wind power began in earnest. Over the last two decades, wind power has become a crucial component of the grid’s power supply both at home and abroad. Currently still under construction, at 7-megawatts the UK’s Hornsea Wind Farm will be the world’s largest when completed in 2020. New York, the 15th windiest state in the US, currently has 20 wind projects in development. With a single turbine
Wind’s moment has arrived, and it stands to play a crucial role in the future of New York’s downstate electric grid. Offshore wind represents an infinite energy resource for the region. Wind does suffer one major drawback relative to some other sources in that it is intermittent and, to a degree, unpredictable. In addition, wind may not produce electricity when grid demand is at its peak, evidenced by Texas utilities providing nighttime electricity free of charge due to surplus production of wind energy. To mitigate for intermittence and allow for wind power to reach its maximum potential, large scale energy storage technology – batteries – also needs to mature, allowing for the storage of cheap power produced during peak periods.
While still intermittent, offshore wind is significantly more reliable than its onshore counterpart, an advantage to New York given its proximate access to the former. Moreover, while offshore wind installations are currently more expensive than those onshore, A 2017 report from McKinsey stated that this is largely due to offshore being a more nascent technology, and predicts that prices will fall quickly as the technology scales and comes to match the maturity of its onshore counterpart. Adding battery storage to the mix and allowing for wind generated power to serve the grid at peak demand – and thus peak price – can only help in this regard, allowing for better optimized pricing of wind-generated power.
When people think of geothermal power, they typically think of hot springs and geysers, and they are not wrong. Geologically active Iceland, for example, sees almost 100% of its energy come from renewable sources. Geothermal power makes up a large portion of this, with nine out of ten Icelandic homes heated by geothermal sources. We see something similar in New Zealand, where geothermal power generation makes up 13% of installed capacity. The largest geothermal plant in the world is here in the United States, the Geysers Geothermal Complex in Northern California. Generally speaking, geothermal power is similar to hydroelectric in that it produces power at a constant rate, avoiding the issues with intermittency that we face with sources like wind.
Though the focus of this article is grid-sourced renewable energy, the growth and maturity of home geothermal installations bears mentioning. Installing geothermal in your home does not require that you live next to a volcano. Geothermal heat pumps instead make use of the earth’s temperature constancy at depths greater than 20 feet. This temperature constancy allows heat pumps – generally using grid electricity – to pull heat from the ground when seeking to warm the air, and to force heat from warmer air into the ground when seeking to cool a home. These systems are extremely efficient, and allow homeowners to take advantage of the planet’s constant core temperature regardless of where they live.
Biomass is a broad energy category representing organic matter that is used for fuel. Sources of such organic matter vary widely, including both virgin agricultural products and waste products from other applications. Biomass burning for energy production is generally a simple process akin to the use of fossil fuels, where heat is converted to energy. The similarity to fossil fuels does not end there, which is largely why biomass represents the most controversial renewable energy source. While biomass fits the technical definition of a renewable in that sources are replenishable on a human timescale, it can also be a significant polluter in its own right, emitting carbon during the combustion process.
Emissions stemming from biomass complicate the source’s potential as a component of a renewable-centric grid. Biomass’ environmental impact is largely tied to fuel source, both the organic matter used and where that organic matter was grown. Suffice it to say, there exists a fundamental difference in terms of carbon output between growing crops for fuel on otherwise unproductive land and cutting down virgin forest for biomass to use in electricity. Biomass’ overall impact can be significantly mitigated if land is replanted after harvest, allowing for the next crop of organic matter – whether that be trees, sugarcane, corn, or some other potential fuel product – to capture carbon equivalent to the matter combusted as fuel.
Some of biomass’ more interesting applications involve the use of waste products for electricity production. The UK supermarket chain Sainsbury’s, for example, is diverting food waste from landfills and instead converting it to biofuels and electricity production. Efforts like these are particularly important in the fight against climate change, as anaerobic decomposition of organic matter produces methane, a highly potent greenhouse gas. Globally, animal farming accounts for approximately 15% of total greenhouse gas emissions, with much of that coming in the form of methane from manure. An ongoing project in North Carolina seeks to use manure as a fuel source, turning hog farms into biogas producers by converting their methane emissions into biogas. In a similar vein, Oswego, NY plays host to a waste biomass plant, combusting waste from municipal and industrial sources for local power generation. The above efforts represent the best of biomass-driven energy production, converting what would otherwise represent organic waste into organic energy production.
If our energy future is to be a renewable one, we cannot depend on any single renewable energy technology. The sun does not always shine. Droughts occur. The wind does not always blow. A resilient renewable energy future is a diversified one, maximizing the utility of renewable technologies while determining what fits best where on a case by case basis. We need hydropower for our baseload needs, wind and solar for their cheap utility, geothermal where it is available, biomass to keep waste out of our landfills, and batteries to help distribute it to times of peak demand. While the grid of the 20th century assumed the existence of cheap, plentiful, consequence-free fossil fuels, that assumption has become rather faulty in the 21st, requiring a deep rethink of our energy future.