What is Renewable Energy?
The challenge is to reduce the enormous amount of fossil energy we use and replace it with cleaner energy. Pollution has an enormous impact on human health and the integrity of natural systems, so less of it is better for everyone. Renewable energy technologies convert energy from inexhaustible sources into electricity. The energy source in the case of solar panels (photovoltaics) is the sun, whereas the energy source for wind turbines is the velocity and mass of the wind. Conventional energy sources include fossil fuels like coal, oil and natural gas. Nuclear fuel is also non-renewable.
Renewable energy technologies require fossil energy to manufacture (as 90% of world energy consumption is currently derived from fossil fuels and renewable energy technologies are not yet made from renewable energy – though this is the long-term goal). The process of manufacturing renewable energy technologies result in various forms of pollution including those from steel production, concrete production, plastics production, and electronics production. This is no different, however, than the pollution from manufacturing conventional energy technologies which require similar materials (steel, concrete, plastics, and electronics), but includes pollution from their fuel sources like oil and natural gas refining and coal production.
Another very important concern that might relate more to renewable energy technologies is the land-use where they are sited. Installing solar panels or wind turbines on grasslands has the potential of disrupting natural ecosystems. It is better to use brownfield sites (land that has already been used for industrial activities), or in the case of solar, built environments like rooftops and parking lots, for the installation of renewable technologies.
It is clear that reducing energy consumption is always the best choice to reduce pollution.
The main reason for installing commercial-scale renewable energy technologies is to reduce pollution compared to conventional fossil-fuel technologies. To do this, the renewable technology must generate more energy when compared to the energy consumed in their manufacture (and to install and maintain). Every 1 unit of fossil energy invested up-front in the renewable energy technology permits more units of energy to be delivered from the sun or the wind.
The more technical term for this is EROEI: Energy Returned over Energy Invested. A technology must have an EROEI greater than 1. If it is less than 1, that means you have used more energy making the technology than you will generate in the life-cycle of the technology. A contemporary example of this is fusion, which currently uses more energy than it generates.
Here are some examples of EROEI:
In the case of solar, the energy it takes to manufacture a square meter of panel is 1150 kWh. A kWh, or ‘kilowatt-hour’, is the same unit of energy in which you purchase your electricity. In Lethbridge, a square meter of solar panel will produce about 225 kWh of electricity each year. If the solar panel lasts its expected lifespan of 25 years, it will produce 5 times more energy than it took to manufacture it. That is an EROIE of 5.
Similarly, the energy it takes to manufacture a common 2-megawatt wind turbine is almost 2.8 million kWh. The wind turbine will produce about 3.5 million kWh each year for an expected lifespan of 20 years. Generally, a wind turbine will produce 25 times more energy than it took to manufacture it, for an EROEI of 25.
The EROEI is a useful way of evaluating the energy balance for technologies or even fossil energy sources. For example, it currently takes 1 unit of fossil energy to produce 20 units of fossil energy in conventional oil production. Unconventional oil production, like bitumen production which requires large volumes of steam generated from natural gas, has an EROEI typically lower than 4. This is a main reason why bitumen receives a much lower price per barrel on the market.
What is Renewable Energy?
Today, it is a process of making fossil fuels more productive. Take one unit of energy from a fossil fuel, use it to make a renewable energy technology, and generate 5 to 25 times more energy over time. Because you are increasing the efficiency of the original unit of fossil fuel, you are creating smaller amounts of pollution per kWh of electricity produced.
To expand on this concept, one unit of fossil fuel can be burned to make steam to generate electricity (at an efficiency of about 35% for coal, and as much as 50% for natural gas). This same fuel might be burned to make a renewable energy technology which, in turn, will generate energy over time. The same amount of fossil-fuel is burned in both cases, creating the same amount of pollution. The renewable energy technology will, however, produce many more times the amount of energy over time, so the pollution is, in essence, diluted. Less pollution per energy produced is the result. The following example shows how the emissions per kWh of electricity is reduced over time, compared to the fossil technologies that currently comprise the Alberta electricity system.
The caveat!
Renewable energy technologies have to be installed in locations that maximize sun or wind exposure, and all of the electricity generated must be used. To take the example of solar panels, if the panel is installed in a location that is shaded part of the day, it will not produce at its maximum potential. This means that the pollution created up-front is not going to be diluted as much over time. It is an important concept, as it is possible to make more pollution than conventional sources using poorly located renewable technologies. Maximizing the potential also requires a well-designed and operated electricity system (grid) that will receive electricity when it is generated and provide electricity when it is needed. If the electricity using renewable technologies is produced when it is not required, it is wasted. The electricity grid must become a shock absorber for intermittent generation from renewable technologies.
Global societies have recognized the undesirable side effects of fossil fuels (coal, gas and oil). First, the reduction of energy use is the most effective means of reducing pollution. Second is using the energy more efficiently: replacing fossil fuel electricity generation with renewable energy technologies improves efficiency and reduces pollution. It will take a monumental effort to assign our remaining fossil-fuel allowance to manufacture and install renewable energy technologies in an effort to vastly reduce fossil-fuel consumption in the future. And there will be significant challenges in designing and operating an electricity grid based on intermittent sources: a combination electricity storage and managing electricity demand by industry and households will be required. It is likely that natural gas generation will be required in Alberta as a back-up when demand exceeds generation.
In summary, when one wonders what renewable energy is today, think of it as improving efficiency (making more energy from each unit of fossil fuel energy), and think of it as a means of reducing pollution.
We live in a full world: renewable energy technologies are an existing way to do better and begin to reduce our environmental impact.