Getting up from your bed, you turn off your air-conditioner while making a beeline for the refrigerator. Grabbing your breakfast, you browse your phone for any regular updates on local news or even reddit. Shortly after brushing your teeth and dressing up, you finally head out for your 9 to 5 work.
And yet, when we think about Energy, our minds only revolve around that of Electricity. What about that of space heating and cooling to keep ourselves comfortable, as well as that of transport fuels, the very thing which powers most of our vehicles?
Energy is present everywhere in our seemingly normal everyday life. However, in the near future, as our pool of resources deplete, we would need to start deciding between secure, green and cheap energy.
Or is it possible to have them all?
The Sources of Energy
All usable forms of energy can be grouped into 3 main categories: That from solar radiation, gravity and radioactivity.
Such energy can be obtained directly through photovoltaic panels and solar hot-water systems, where the light and heat from the Sun directly affects the end product, which would be electricity and hot water respectively. Another way of harnessing the energy would be through indirect means such as that of CSP (Concentrated Solar-Power) plants, where light and heat from the Sun is concentrated by various reflectors to drive a heat engine, which in turn drives an electric generator.
In addition, differential solar heating in different parts of the Earth results in a difference in air pressure, hence leading to wind, while waves in the ocean is a product of the shearing actions of the wind. As evaporation of water is driven by solar radiation, the Sun play’s a crucial role in hydropower plants, while solar warming of the Earth allows us to take advantage of both Air-Source Heat Pumps as well as Ground-Source Heat Pumps. Lastly, as all life stems plants, which grow by means of photosynthesis, biomass can be attributed to the Sun as well.
Not only does Gravity play a crucial role in the occurrence of waves, it is responsible for precipitation, which gives rise to the numerous water bodies on Earth and the Hydropower plants. The Earth’s gravity drives air-warmed water into the soil, which can be used as energy sources by Ground-Source Heat Pumps and Geothermal Energy Plants, while it also drives the accumulation and compaction of organic debris eons ago, hence leading to the creation of fossil fuels.
It is the ultimate source of solar radiation in the Sun, and it is also the predominat source of heat generated within our planet, giving rise to geothermal energy.
It is important to note that unlike nuclear energy, which is entirely artificial, the isotope of uranium (238 U) responsible for geothermal energy is quite harmless and entirely different from that of nuclear-power generation (235 U): 235 U has a half-life of 700 million years, while 238 U has a half-life of 4.5 billion years.
In addition, the degree of enrichment necessary to support nuclear energy production (about 3.5% 235 U) is varsely different from that needed for weapons production (ranges from 20% to 85% 235 U). Therefore, there is no reason to link civilian nuclear energy production to that of military weapons production. However, current estimates suggest that at current production levels, uranium reserves will be depleted in 80 years.
Power Density and Carbon Emissions
If we were to compare the power density among the various energy sources, we would have a diagram above. And yet, if we were to compare the carbon emissions among them, we would have a diagram below:
Which graph should take precedence?
Before we move on to the next section to address the question, it is crucial to note that carbon emissions from energy production plants can be reduced through Carbon Capture and Storage (CSS). In essence, CO2 is extracted from the exhaust gases of a power station before being injected by means of boreholes into deep underground strata, retaining it for more than a thousand years. As such stratas are not found everywhere, such C02 may need to undergo long distance transportation via pipelines to dedicated storage facilities. Technologies for CCS are well-established, with 51 large scale CCS facilities in operation or under construction globally.
Thermal energy storage is feasible. As we have discussed above, it can be done through the storage of hot water in large tanks at a commercial scale, which can then be used by consumers at a later time.
However, commercial storage of electricity is still a challenge. Although it is possible to store electrical charge in chemical form, the energy losses incurred as well as the use of expensive materials for electrolysis makes this economically unviable. Therefore, the only other alternative would be that of hydroelectric pumped storage, where spare electricity during low demand periods is used to pump water uphill to a reservoir, whence it can be released later to generate power using hydroelectric turbines. One such example would be the Cruachan site in the Highlands of Scotland, capable of producing up to 440 MW while sustaining it for a maximum of 22 hours.
Baseloads and Dispatchable power
Another thing to consider would be grid stability. As the demand for electricity fluctates over the course of 24 hours, managers of large regional electricity grids would need to use load tracking to match the supply with the demand down to the minute: Too much and there would be localized overload and damage; too little and there will be frequent outages. Therefore, it is imperative that these managers have access to reliable energy production plants which can be brought on or offline quickly.
Therefore, completely relying on renewables to support national grids would be a foolish idea. Although some renewables such as hydropower, geothermal, biomass and tidal are able to offer some predictable baseload and dispatchable capabilities, their power density still pales in comparison to that of fossil fuels. In addition, other renewables such as that of wind, solar and wave offer even lower predictability in terms of hours. Coupled with its high cost and low power density, there are few incentives.
In our fight against climate change, we must take caution, and not have our ideas backfire. One notable example would be that of Germany’s Energiewende, where its low carbon transition led to an increase in total annual global emssions.
We can have secure and cheap energy: That is exactly what fossil fuels have been delivering for the past century. We can also have secure and green energy, provided we do our best to minimise energy demand, and outfit current and upcoming fossil fuel plants with CCS technology. In addition, we can step up the use of nuclear power plants (although there is much to be debated with regards to this) and look more into thorium, the alternative fuel to uranium. This, however, would increase the cost of energy by at least twofold.
As for the heat & cooling sector, use of better building materials may be able to cut total energy usage by up to 35%, while investments by local governments into public transport infrastructure such as trains, buses and sidewalks would lead to a 10% reduction in all greenhouse gases produced by a typical family. In addition, implementing additional taxes on private cars would decrease congestion on the road while reducing car emissions at the same time.
For instance, a car in the United States of America would cost only $20,000, while that same car in Singapore would cost a whooping $110,479. Although the consumers aren’t particularly happy about that aspect, together with decent public transport infrastructure, this led to a per capita C02 emission of 7.12 metric tons in Singapore, compared to 16.38 metric tons in the United States of America.
Change is expensive. In the not-so-distant future, we would need to decide between a hole in our wallets, or a hole in the ozone layer.
I think the former is better.