Sea vegetables need sunlight to grow and we often use the sun to dry them post-harvest. It seems only fitting, then, to also use the sun’s power to process them. In early 2024, Maine Coast Sea Vegetables will be doing just that, when our new solar electricity farm comes on-line. Regular readers of this blog may recall we first mentioned the possibility of a solar farm in a 2021 blog post titled “Sustainable Seaweed Company Practices”. We’re happy to report that solar energy will soon help power our processing plant.
The dulse crop is sun dried after harvest.
Every hour, enough sunlight shines on the earth to power the entire planet with solar energy for one year. Sunlight can be converted into electricity with photovoltaic (PV) panels, and multiple PV panels lined up in arrays are popularly known as solar farms. It seems as though one can’t drive more than 20 miles in New England without seeing a solar farm, some of them quite sizable. As they increase in size and numbers there has been some push-back, but overall, public support remains strong. Surveys show that most people, 70% or more, support expanding US solar energy production to reduce fossil fuel use and air pollution, fight climate change, increase our energy independence, and create jobs. Sixty percent of voters now agree that solar power “is affordable” and “cost effective.”
Beyond this basic understanding and widespread appreciation of its benefits, though, solar energy and how it contributes to sustainability is still somewhat mysterious to many. This lack of understanding can fuel opposition to new solar farms. Who is building these new solar farms and who owns them? How do they affect the environment? What’s their lifespan? How do they even work? We address these questions and others in this blog post, from the perspective of a seaweed company striving for sustainability.
The Birth of Solar Electricity
Plants and sea vegetables have been turning sunlight into energy for millions of years through the process of photosynthesis, and humans long ago realized that the sun could heat water and dry clothing, crops, and other things. The sun has been used to dry sea vegetables for thousands of years and it’s still one of our favorite methods. Solar energy has also been used for less peaceful purposes. It’s said that in 212 BC, the Greeks used bronze shields to focus sunlight onto enemy Roman Empire wooden ships besieging Syracuse, setting them afire.
In 1839, the French scientist Edmond Becquerel discovered the photovoltaic effect, whereby the electricity generation of a ‘wet cell’ battery was magnified when exposed to sunlight. In 1881, the American inventor Charles Fritts created the first solar cells made from selenium wafers, and in 1905 Albert Einstein published his paper on the photoelectric effect (from the US Dept. of Energy “The History of Solar”). Thomas Edison and contemporaries such as Henry Ford and tire manufacturer Harvey Firestone all recognized the potential of renewable energy from the sun, wind, and tides.
Succeeding scientists built on these early findings. In 1954, commercially feasible photovoltaic energy production was born when Bell labs developed the first silicon photovoltaic (PV) cell capable of turning enough of the sun’s energy into electricity to run everyday electrical equipment. A PV cell is the basic building block of solar panels, which may contain 32 to 72 cells arranged in a grid pattern. When sunlight strikes a PV cell, it excites the electrons in the cell’s semiconductor material, creating a flow of electricity.
Solar Electricity Becomes More Efficient
The first PV cells weren’t terribly efficient; just 4% to 11% of the energy held in sunlight was converted into electrical energy, and they were also costly. In 1970, Dr. Elliot Berman, with help from Exxon, brought the cost down from $100 per watt to $20. This was progress, but it was still far too costly to make solar power an economical alternative to fossil fuels. Fortunately, private sector and government funded research continued and has brought us to where we are today: PV cells are now about 17% to 22% efficient and the cost per watt for utility scale systems is about $1. PV cells continue to improve with each generation of production.
Solar Electrical Basics
Before we discuss our solar farm we should discuss some basic electrical concepts. We’ll start with a watt, named after the engineer James Watt, and understood as a unit of power that measures the rate of energy transfer. One watt is equal to one ampere under the pressure of one volt. Delving deeper requires far more technical detail, so we’ll leave that as optional reading (Wikipedia, for example). Suffice it to say, one watt is a small unit of power, and it forms the basis for how electricity usage is measured and billed.
The power consumption of small devices, such as lightbulbs, is usually measured in watts, while that of larger devices is measured in kilowatts (kW), or 1,000 watts. Industrial electrical generation is usually measured in multiples of kilowatts. One megawatt (MW) is equal to 1,000 kW (1 million watts), and one gigawatt (GW) is 1,000 MW (or 1 billion watts). Now we’re talking juice!
A watt is a unit of power, or the ability to do work, but it’s not a measure of how much work is performed over time. Without knowing that, utility companies couldn’t charge their customers. This is where watt hours (Wh) and kilowatt hours (kWh) come in. One Wh is the consumption of one watt over one hour. Since homes, businesses, and other human activities use far more than that in one hour, the more standard measure is kWh. Ten 100-watt lightbulbs left on for one hour equals one kWh (1,000 watts in one hour). One 60-watt bulb left on for 3 hours equals 0.18 kWh.
The sun’s energy is also often measured in watts. A peak sun hour is defined as one hour in which the intensity of solar irradiance (sunlight) reaches an average of 1,000 watts (or 1 kW) of energy per square meter (roughly 10.5 square feet). Peak sun hours are when solar irradiance is at maximum, and their duration varies depending on location and time of year. As one travels north, or in regions that experience more fog or cloud cover, peak sun hours diminish. Maine, on average, experiences 3 to 3.5 peak sun hours per day, with more in the summer and less in the winter. Solar arrays are usually rated on the basis of one peak sun hour, so an array rated for 1kW should output 1kW during a peak sun hour.
Another fundamental electrical concept is the difference between alternating current (AC) and direct current (DC). Alternating current changes direction between negative and positive poles in a regular, wave-like pattern. Direct current always flows in one direction, usually from the positive to the negative pole. Batteries output DC power and most electronics use DC power. Photovoltaic power is also DC.
The electric grid and most of the electricity we use comes as AC power. This is because AC is readily converted to different voltages using transformers, and it is more easily transmitted over long distances. Rectifiers, such as the power supply for your computer or cell phone charger, convert AC to DC. Inverters do the opposite, converting DC to AC, and solar panels require inverters to convert the DC power they generate into the AC power used by homes, businesses, and the electrical grid.
Solar installations are typically rated for both their DC and AC outputs. The theoretical power output of a solar installation is estimated by multiplying its AC output by the number of hours it operates and the solar irradiance received during that period. This calculation yields the total energy produced, measured in megawatt-hours (MWh) or kilowatt-hours (kWh).
The last two variables (hours and irradiance) are accounted for by a factor known as solar capacity. Solar capacity is a ratio, expressed as a percentage, of the actual power produced by a solar system in a particular period of time (usually a year) to the maximum possible power that can be produced by the system. Solar energy has a low capacity factor relative to fossil fuels for the simple reason that the sun only shines part of the day. It’s also affected by things such as weather and average cloud cover. Commercial-scale solar installations in Maine have about a 16% solar capacity factor. Arizona and Utah have the highest solar capacity factor of all US states, at 29%.
Solar installations can be grouped into three broadly overlapping categories depending on application and scale.
Small-scale or distributed solar. Also known as rooftop solar because this is where operators often place their panels. Distributed solar is typically located where the electricity will be used. Under Maine statute, distributed solar can be anything with up to 5MW of capacity. It includes everything from rooftop solar serving a single home to small-scale commercial farms serving many homes or businesses.
Generous federal subsidies can help finance installation, and a state policy known as net metering ensures residential solar owners are compensated when they put more power into the grid than they use. Under net metering, every excess kWh flowing into the grid from a rooftop solar array on a sunny summer day can be banked for up to a year and applied on a dark winter day when the owner’s electrical usage exceeds their solar output. In Maine, a 5-8KW system covers most of the electrical usage of an average home, with a payback period of 10-12 years (SolarSage).
Community solar farms can range from 250 KW to 10MW and they generally provide electricity to the grid rather than directly to homes or businesses. Community solar does not have to be located where the electricity is actually used, just within the same locale.
A community solar project sells the electricity it generates to local subscribers in the form of energy credits. One energy credit is equivalent to one kWh but costs less thanks to government subsidies and the competitive advantage solar electricity now enjoys over fossil fuel electricity. Subscribers are allocated credits for purchase based on their historical usage and the capacity of the solar farm. They use those credits to offset their utility’s electricity bill, with an average savings in Maine of 10% to 15%.
Community solar benefits under a state policy known as net energy billing (NEB), which is similar to net metering. In the summer a customer may purchase more solar credits than they need, but they can use them later in the winter when the opposite occurs, so long as they get used within a year. Community solar allows low-income households that can’t afford rooftop solar to still benefit from solar energy. This is the kind of solar farm Maine Coast Sea Vegetables invested in.
Utility or grid-scale solar can range from 10MW to enormous, several gigawatt industrial projects. Utility solar projects deal directly with utility companies and not with consumers, but consumers benefit because solar power is less expensive than fossil fuel power. In theory, utilities should pass the savings along to their customers. Utility solar is an important way for states and nations to meet clean energy goals. In 2022 approval was granted to the Three Corners Solar Project in Kennebec County, Maine. Capable of generating 152 megawatts of electricity, or enough to power about 30,000 homes, this would be Maine’s largest grid-scale solar project. The project will cost in excess of $200 million and occupy about 900 acres of land.
About 125,000 homes are said to be powered by solar energy in Maine as of 2023. This is pretty good for a state of just 1.4 million people. Much of this growth comes from community solar projects, but Maine has also had a number of utility-scale projects come on line, with more in the planning or permitting stages. However, this growth hasn’t come without controversy, and critics raise a number of issues.
Aesthetics. Several acres of gleaming solar panels aren’t the most attractive sight to some people, especially when they occupy what was once field or forest. There are ways to mitigate visual impacts, such as locating installations away from roads or screening them with trees, fencing, or hedges, but people who like Maine for its natural beauty still object.
Farmland loss: Farmers in Maine and elsewhere are now also farming the sun. For many, this has been a game-changer because it helps them continue growing traditional crops while weathering low prices, variable yields, and a changing climate. Critics, however, bemoan the loss of productive farmland. Although farmers tend to plant their solar farm on their most unproductive land, this isn’t always the case. Agrivoltaic farming could be a solution. Under this practice, certain shade-tolerant crops such as broccoli or lettuce are grown beneath the solar panels.
Deforestation: Installing solar farms in Maine often entails cutting down trees. No surprise there, considering Maine is the most forested state in the nation with 90% coverage. Critics point to environmental damage and habitat loss. However, this assumes that forests represent nature at its pinnacle or most pristine state, when in actuality the situation is far more nuanced. Different types of forest differ in habitat value, with mixed hardwood stands being of higher value than the dense spruce stands so ubiquitous in Maine. Furthermore, the openings and edges (where forest meets clearings) created by solar farms encourage greater species diversity. Small prey animals such as rabbits thrive in such environments, as do songbirds, flowering plants and shrubs, and pollinators.
Carbon footprint: Photovoltaic power comes with its own carbon footprint. Manufacturing solar panels is energy intensive, and when forests are cut down to install solar farms, their ability to suck and sequester carbon from the atmosphere is lost.
These are not easy matters to address because they require what is known as a life cycle analysis (LCA). This is where the inputs and outputs of a process or activity are modeled over its lifespan to measure its environmental impacts. A carbon LCA focuses on carbon footprint and must account for the type of PV panel; materials, mining, and manufacturing energy sources; expected energy production of the installation; and other factors.
Generally, a 30-year lifespan is assumed for solar installation LCAs. A common measure in these studies is energy payback time (EPBT, the point where solar energy output exceeds energy inputs). Depending on the variables mentioned above, EPBTs for PV installations can range from <1 year up to 10 years. Beyond that time frame, the installation produces more energy than required to build it. Numerous solar LCAs have concluded that solar installations produce far more energy than they consume and have a much lower carbon footprint than fossil fuels.
Runoff: Critics sometimes claim that solar panels lead to rainfall runoff and erosion. Although this can be an issue during construction, studies show solar farms do not increase runoff once the initial broken ground has regrown.
Solar farm construction has to be managed to minimize runoff and erosion. Not visible in this photo are the erosion control measures located below the muddy area.
Toxins: Depending on design, solar panels may contain copper, cadmium, or other metals, and their support frames may include aluminum. However, solar installations by design are inert and extremely durable. Studies find that the risk posed by leaching of heavy metals used in their construction, or that posed by fire, is extremely low. Unfortunately, the internet has multiple sites emphasizing this hazard. When perusing such websites, it’s always wise to consider the motives of those behind them. Obviously, there are powerful special interests opposed to anything threatening the profitable status quo! Critics do have a point, however. At the end of their useful life of 30+ years, solar panels must be responsibly recycled and the infrastructure for that isn’t yet in place because the industry is so new.
Ideology: Finally, there are those who, because of political ideology or other reasons, don’t believe in human-caused global climate change (global warming), or who simply want to preserve the status-quo reliance on fossil fuels because they believe to do otherwise threatens the American way of life. Unfortunately, such people can find plenty of ‘information’ on the internet to support their beliefs.
Ultimately, every solution comes with costs, but we at Maine Coast Sea Vegetables believe that solar energy must be an essential part of the solution to global climate change. It is deeply concerning that the Gulf of Maine is one of the fastest warming regions of the entire global ocean. What will happen to Maine’s iconic lobster fishery, let alone our treasured sea vegetables, as the ocean continues to warm? This is why we made the commitment to going solar.
The warming Gulf of Maine is causing changes in the distribution and abundance of species such as sugar kelp. Meanwhile, invasive species such as Dasysiphonia japonica are taking over areas where sugar kelp once grew.
The Maine Coast Sea Vegetables Solar Farm
Over ten years ago, when it became evident MCSV had outgrown its then location, we purchased a 67-acre plot in our hometown of Franklin to build a new processing facility. However, as plans progressed, we ended up building our new home elsewhere. The new building’s orientation, roof angle and height, and the prevailing winds were not conducive to rooftop solar, so we looked at the first site with new eyes. About 15 acres of it was a former, sun-drenched gravel pit; the perfect location for a solar farm.
We partnered with Greenbacker, an investment management firm and energy business focused on renewable energy. Greenbacker financed the farm and will operate it through a wholly-owned subsidiary. Engineering was done by Borrego Energy, one of hundreds of new, US based companies specializing in renewable energy. After several years of planning and navigating state and local permitting, we finally broke ground in 2023. Grasses, shrubs, and small trees had started to take over the gravel pit, but other than that and a few large boulders, site preparation and disturbance were minimal. No forest was removed and very few large trees had to be taken down. During design we took care to maintain buffer zones between the solar farm and the nearby road and our closest neighbor.
MCSV solar farm about halfway completed.
The farm’s size was limited by the capacity of the nearest electrical sub-station. Maine’s privately owned grid operators have been slow to modernize, which has actually been a problem for other solar farms in the state. The system consists of 4,576 solar modules with a combined rated output of 1,990 kW, or just under 2 MW. After accounting for Maine’s solar capacity factor of 16%, it turns out our 2MW farm might actually produce about 320 kW per hour over the course of a year. Multiplied by 8765 hours per year, annual output comes to 2,804,800 kWh. How many Maine households could this theoretically power?
Maine residents use less electricity per household than almost every other state in the nation except Hawaii, but we pay some of the highest rates in the nation. According to the Governor’s Energy Office, in 2022-23 the average Maine residence used 550 kWh per month (6,600 kWh per year), at 23 cents per kWh (including delivery and supply).
It turns out our 15-acre solar farm produces enough electricity to power 424 average Maine homes! This compares favorably with other Maine community solar projects. For example, Maine Public reported that a 17-acre solar farm in Acton, Maine with a rated capacity of 4 MW (twice the size of our farm) would produce 5.2 million kWh, or enough for about 800-850 households.
However, instead of providing electricity directly to homes and businesses, our solar farm delivers it to Versant Power as part of their overall energy portfolio. Versant Power supplies electricity to 165,000 customers in northern and eastern Maine. Some of their customers located in our area (mostly small businesses like ours) will be able to purchase credits from the solar farm, which they can then use to offset their utility electrical bills by 10% to 15%. Not only does this save them money, it also reduces their carbon emissions.
How much carbon will our solar farm prevent from entering the atmosphere? According to the US EPA Greenhouse Gases Equivalencies Calculator, 2,800,000 kWh produced from fossil fuels is equivalent to 1,211.42 metric tons of CO2. It may surprise you to learn that for every mile an average car is driven, it produces almost one pound of carbon dioxide (0.88 pounds according to the EPA). This might have you scratching your head. How can a car create almost one pound of CO2 when it's only driven one mile? The answer is that most of the weight of the CO2 doesn't come from the gasoline itself, but the oxygen in the air. When gasoline burns, carbon and hydrogen separate. The hydrogen combines with oxygen to form water (H2O), and carbon combines with oxygen to form carbon dioxide (CO2). When it’s driven 2,500 miles that same car releases about one ton of CO2. Thus, in one year our solar farm reduces the carbon emissions equivalent to driving almost 3,000,000 miles!
By generating clean, renewable energy instead of fossil fuel energy, the Maine Coast Sea Vegetables solar farm reduces CO2 emission by 36,342 tons over its 30-year life span. In the big picture, of course, this is just a drop in the ocean, but collectively, hundreds of thousands of companies and millions of people making the same commitment will have a huge impact. We’re grateful that we, along with our customers, can be part of the solution.