4-2 Non-Fossil-Fuel Energy Sources
At present, the greatest potential for growth on non-polluting energy is from solar and wind energy. These technologies have advanced quickly in the past few decades and they are now the cheapest forms of energy to build and install. That said, there are limitations. The sun is not available at night and is typically not strong in the winter—especially at northern latitudes—and the wind doesn’t always blow when it’s needed most. An example of that is provided in Box 4-1 below.
Box 4-1 Wind Versus Cold on the Canadian Plains
The province of Alberta has long depended on coal for electricity production, but that is changing quickly; the last coal-fired plant will be shut down in the next few years, and Albertans will rely on a mix of gas-powered generation and wind and solar (and some older hydro) power. Fossil fuels are expected to be phased out entirely within decades. This raises concern about energy availability at times when it is needed most, and a good example of that was provided in late December of 2021. For about 10 days, western Canada was plunged into severe cold by an Arctic air mass. Temperatures in Calgary reached -30° C, but as shown on Figure 4-3, the extreme cold was accompanied by an eerie calm, and production from wind turbines dropped accordingly. Although this particular temperature-versus-wind relationship doesn’t always apply on the Canadian plains, it’s common enough that electrical utilities need to take steps to ensure that the electricity is there when it’s needed most. The answer doesn’t come from solar, as that is also at its lowest availability in late December.
Exercise 4-1 Intermittent Wind and Solar Resources
The following is an interactive version of Exercise 9.2 Intermittent Wind and Solar Resources the Environmental Geology textbook.
A combined wind turbine and solar PV energy facility (like the one shown on Figure 9.1.9 in the text). has been established to serve an area with about 50,000 homes in southern Alberta It comprises 150,000 solar modules at 600 W each (total capacity 90 MW) and 20 wind turbines at 5 MW each (total capacity 100 MW). The region is often sunny and has good wind resources, but of course there are cloudy days and dark winter days, and there are calm days.
The following table, which is based on the weather conditions for a week in late spring, shows how many hours of strong sunlight equivalent* there are on each day to power the modules at their 600 W capacity, and how many hours of strong wind equivalent are available to power the turbines at their rated 5 MW capacity.
Complete the other rows of the table to work out the average amount of energy produced by each system on each of the seven days, and the total amount of energy produced. For example, to estimate the daily energy production for the solar array, in MWh, multiple the number of hours of strong sun equivalent by the total capacity of the system (90 MW). For wind, multiply the hours of strong wind equivalent by the total capacity (100 MW). The first column (Monday) is done for you.
(*For example, on a given day there might be four hours of strong sunlight, three hours of weak morning or evening sunlight, and six hours with conditions ranging from partial to complete cloud. These might all add up to eight hours of “strong sunlight equivalent”.)
Hydro electricity is discussed in section 9.2 of the textbook, where an important distinction is made between facilities that have dams and reservoirs, and those that rely on the flow of a stream at any particular moment. A reservoir allows us to store energy, for hours, days, weeks or even months. That stored energy can be used when it is needed most, and therefore can be available to balance energy systems, like wind and solar, that have little or no storage capacity. As noted in the textbook, there is limited potential and little public appetite for growth in the hydro sector, so, while it is an important source now, especially for its storage capacity, it is likely that the contribution of hydro in our energy mix will decline in the coming decades.
Exercise 4-2 Power and Energy
The following is an interactive version of Exercise 9.3 Power and Energy in the Environmental Geology textbook.
Geothermal energy systems (section 9.4 in the textbook) are practical in many areas with volcanic heat flow, but those are limited on Earth, and so the future potential is limited. Although geo-exchange systems can be deployed almost anywhere, geo-exchange is not a source of energy. Instead, it is a means to efficiently heat and cool buildings, and so can save a lot of energy that would be used for those purposes. Please complete Exercise 9.3 Power and Energy before moving on to section 9.5 in the textbook. Wave and tidal energy systems are covered in section 9.3. As noted, there is huge potential for growth in this sector, but proponents have struggled to develop systems that are cost-effective. At present, none come close to solar and wind in that respect, although that could change as research and deployment continue.
There has been no net growth in the amount of energy produced by nuclear fission reactors for the past thirty years, and while some new reactors have been built, many existing ones have been decommissioned. This limited outlook for nuclear fission is partly a result of its checkered past (as described in Box 9.2 Nuclear Fission Plant Failures in the textbook), which has soured public opinion. The fission industry is not dead, but it is shifting away from Europe and North America towards Asia. There is also evidence of a shift away from large reactors (larger than 1 GW) towards smaller more modularized ones.
Nuclear fusion has the potential to provide the clean and safe on-demand power that we are going to need to replace existing fossil-fuel facilities, but even though there are many teams working on this problem, around the world, a functioning power station is still several decades and many tens of billions of dollars away.
Energy is what makes our modern, comfortable and technological lifestyle possible, but fossil-fuel energy is killing us and we need to make big changes quickly to avoid disaster. Some of those changes involve different ways of generating electricity (as described above) but others involve using less energy overall, and also being smarter about when we use energy, and how we store and distribute it, as described in section 9.6 of the textbook. As consumers, we can reduce our overall energy demand, and we can also change our habits concerning when we demand it. Utilities can reduce the need for extra peak-time generation by storing energy, and also by sharing energy over long distances.
• What is the primary source of electrical energy in the state, province, or country where you live?
• Is that changing at present, or is it expected to change significantly in the coming decades?
