How renewable energy can go from hero to zero
A rudimentary understanding of the Ontario electrical grid and how renewable energy such as wind and solar works, quickly leads one to the conclusion that too much wind and solar energy negates the ability of the grid to rid itself of fossil fuels.
The grid is really just a bunch of wires that connect you to an electrical generator.
A “blackout” occurs when the grid can no longer supply people with electricity due to faults in the system or acts of nature like storms or high winds. When this happens, many people use small gas generators for backup power. The generator matches the amount of power used. The more electricity used the more tanks of gas used by the generator. In effect, the generator and the wires connected to household appliances - the load - serves as one's own "mini" grid. However, if too much electricity is used, the generator can't keep up and - depending on the type of generator - either appliances will be damaged or a "mini blackout" will occur. To avoid these problems cooking a meal might start with turning the hot water heater off to ensure the stove doesn’t overload the generator.
When people decide to "get off the grid" to generate their own electricity using renewable energy such as solar panels or a wind turbine, in effect, they create a miniature grid. Electricity is supplied by a battery bank charged by solar panels or a wind turbine. Since it is impossible to continuously match the amount of power used in a home with how fast the wind is blowing or how much the sun is shining, a battery bank is required to store the electricity that is generated. Again, if too much electricity is used and the battery is drained of its charge, another "mini blackout" will occur. On the other hand, if the battery bank is fully charged and the sun is still shining or the wind is still blowing, a "dump load" is required to divert the excess energy to a large resistor. This prevents the destruction of the battery bank or prevent the wind turbine from spinning wildly out of control.
With any grid someone needs to play the role of the grid operator ensuring that the electricity demanded by appliances match what can be supplied by the generator or battery bank to avoid a blackout. A true grid operator has a much bigger job: matching every nuclear, coal, gas and hydropower plant with every factory, mall, hospital, street light, TV and toaster in the province. The challenge is greater, but the basic concepts are the same.
Across any one province, a certain amount of electricity is used all of the time for heating in the winter, cooling in the summer, by hot water tanks, fridges, freezers, office lighting, computers, hospitals, factories running 24 hours, etc. This base amount of electricity used all of the time is called "base-load". Although more electricity is generally required during the day, there is a point during the night, when little activity is going on, that sets a base point for the minimum amount of electricity that gets used continuously. The current base-load in the province of Ontario is about 13,000MW of electricity and represents about two-thirds of the total of all electricity used. Generators that are meant to run all of the time such as nuclear and certain hydropower plants supply base-load.
At the start of a typical weekday, people wake up, shower, cook breakfast... increasing the amount of electricity used. As the day progresses, factories are humming, classrooms and offices are filled … more and more electricity is being used. After a small lull after noon, by suppertime, all of the stoves, TVs, computers, lights, stereos and other appliances that are being used reach a peak (currently 19,000MW) of electricity consumption known as peak-load. As night falls and people go to bed, energy use then tapers off again.
As the demand for electricity rises and falls during the day, it needs to be paired with something much more flexible than nuclear power. Flexible sources such as coal plants, gas plants and hydro-electric dams can all be controlled to meet the demand for electricity during these peaking hours. A number of these fossil (coal and gas) generators will be running but not actually supplying the grid. This insurance is in place in the event that a large generator (such as a nuclear or another large fossil plant) suddenly shuts down or goes off line.
In order to match generation to consumption in real time, some generators must fluctuate up and down constantly. Gas plants known as “peaker-plants” are used this way, but must be running at more than 70% full power in order to achieve the amount of flexibility required. Alternatively, hydro-electric dams can adjust their output quickly by just changing how much water flows across the generator. In general, water is allowed to build up in reservoirs behind the dam at night time when its electrical output is not needed, then used for peak use and fine tuning the grid during the day. Like a battery bank used for home generation, electricity can be stored for later use. However, the amount of hydro-electricity currently available to us that can be used in this fashion is limited and affected by the seasons, so gas plants are still required.
How does wind and solar fit in?
For home power supply, either a gas generator must continuously run or electricity from a battery bank (charged by a wind turbine or solar panel) is required to keep the lights on and appliances running. A home gas generator can also be ‘paired’ with a wind turbine or solar panels. This pairing marries the fossil fuels used by the gas generator to the renewable energy of wind and solar. In other words, the gas generator runs continuously, supplemented by solar or wind.
If the gas generator is ‘solar paired’, it will utilize gas the least during the day when the sun is shining and the most at night when the sun goes down. If the gas generator is ‘wind paired’, its output will vary as the wind fluctuates. When it's windy, more electricity will be generated by the wind turbine with the remaining load matched by the gas generator. As wind speed drops, more of the electricity being used by the home-owner will be generated by the gas generator. The best the generator can produce through wind power is about 30% of its potential output (due to wind speed variations). Therefore, 70% of the electricity supplied by a wind-paired generator comes from gas.
Care must be taken by the operator as damage can occur or blackouts result if the electricity generated by the wind turbine or solar panels exceeds the amount of electricity being used. This example does little to reduce carbon emissions and there is no reduction in fossil fuel dependency. The gas generator must be kept running. People interested in renewable energy for home generation want to get the most out of their wind turbine or solar panels thus opt for the battery bank.
Unfortunately, it is the pairing of renewable energy to fossil fuels that is employed across the wider grid of Ontario and many other jurisdictions. Denmark can store their wind energy by exporting excess wind generation to Norway (and Sweden to a lesser extent). Norway, which derives nearly all of its energy from hydropower, allows the reservoirs behind their dams to swell as they use the wind power from Denmark. When the wind drops off or when Denmark needs their energy back, Norway allows the water built up behind their dams to flow over the generators and export the energy back to Denmark. Alternatively, jurisdictions such as California can use excess wind energy to pump water to the top of a mountain lake. When the energy is needed, water is allowed to flow back down through a generator. By contrast, however, the province of Ontario has married its renewable energy from wind and solar to fossil fuels.
Ontario already produces up to 75% of its electricity free of carbon emissions through nuclear and hydropower. This leaves little room for the ability to displace fossil fuels. The elimination of coal, which once provided both base-load and peaking power, is near completion. Its current output is minimal. As the amount of wind generation increases to the 8,000MW planned by the provincial government, plus increased output from solar generation, the ability to store renewable energy by existing hydropower plants has been greatly exceeded. By default, gas generators are used to pair with renewable energy.
As noted above, some fossil generators are kept running for the unforeseen event of a large generator shutting down. Likewise, additional fossil plants must be kept running in the event of a sudden loss of wind or solar energy, further hampering any reduction of carbon emissions. By not utilizing a storage medium, charged by wind and solar, the province of Ontario could see the ultimate in ironies when it comes to climate change mitigation: an increase in carbon emissions caused by the renewable/fossil energy combination displacing existing carbon free generation.
At the current 1400MW of installed capacity of wind generation, Ontario has already had to pay its neighbours to take excess generation off of its hands, forced dams to "spill" water bypassing their generators and have nuclear units temporarily shutdown. It takes 2 days for a nuclear unit to restart. Increasing wind outlput to 8000MW will only escalate this problem. One can easily imagine the impact of a night when demand for electricity is low and the output from wind energy is high. What does the grid operator do with 8,000MW of wind energy that isn't needed? Wind plant owners are paid more than triple the actual price of electricity and get paid whether they supply the grid or are forced off-line so it makes sense to keep them running. However, additional fossil generators must be kept running to pick up the demand as wind speed drops and while the system waits for the nuclear units to come back on thus increasing carbon dioxide emissions.
No responsible homeowner would omit a battery bank when planning to generate electricity with renewable energy. If we are serious about reducing fossil fuel consumption and dependency a solution to storing existing and future renewable energy must first be found and implemented before forging ahead with any further renewable energy developments.
