Discussions of electrical generation technologies frequently fall into the trap of considering a single factor. One way this occurs is with advocates of a specific legacy technology pointing out a single downside of wind or solar generation as if it’s a gotcha. This is equally true of wind and solar advocates who point at single-factor issues with nuclear or coal, as examples, making the comparison to the more virtuous renewables.
However, there is no single technology which will prevail on all grids in the future. There will be multiple generation technologies at any given time, the mix will change over time, and the specific mix will vary for specific geographies.
The following is my multi-factorial assessment as of 2016 for different forms of electrical generation. The assessment is a simple scale of 1 to 5, and is based on my judgment of each of these technologies which is informed by my background, knowledge, research, and systemic perspective. It is not a quantitative evaluation.
It is unweighted because my weighting would be roughly equal on these points for North America or Europe, but the explicit weighting would vary substantially based on geography. The strict market cost of generation has far outweighed the other factors historically, and only wind and solar’s plummeting costs have made them expand as rapidly as they have recently.
Unsurprisingly, coal falls near the bottom of the rankings. Its challenges in terms of pollution, greenhouse gas emissions, relatively low flexibility, and liabilities make it non-viable in a multi-factorial assessment, with only its position as a form of legacy generation and lower price point making it as dominant as it is. If someone suggested coal as a new form of generation today without its history, it’s hard to imagine the idea would gain traction.
Nuclear’s poor ranking is perhaps more surprising. It’s gained a good deal of favour among various former opponents over the past few years due to its lack of air pollution and greenhouse gas emissions. However, its inflexibility, the high impact of any failures, its high economic cost, and the limitation to roughly 30 countries globally make it much less attractive. In countries where it already exists, in general, very few new reactors are being considered compared to the amount of wind and solar being put on grids. Only China is expanding its nuclear fleet in any substantial way.
Each of these factors is explained below with examples of the reasons for many of the rankings. Not all rankings are explicitly explained, but nuances which would assist in weighting for specific circumstances are discussed.
This is straightforward. Society runs on energy and money. Given a choice between something which costs 3 cents per kWh (LCOE) and something which costs 15 cents, pretty much everything will favour the 3 cents option. (This is why it’s perplexing that the UK conservatives are still pushing for the Hinkley nuclear choice, which costs 15 cents USD per kWh.)
The least expensive forms of new generation today in strict market terms are wind, solar, and methane generation.
Low Negative Externalities
A negative externality is a cost of something which is not included in the dollars paid for it. With fossil fuel electrical generation, negative externalities include CO2 emissions and methane leaks which cause global warming, particulate matter and nitrous oxides emissions which impact lung health, and sulphur oxide emissions which kill trees and lakes. With wind energy, they make a little bit of noise, which some people who live close to them find annoying part of the time. With solar energy, there’s some mining and manufacturing pollution. Hydroelectricity in desert areas or the far north or south can be very low carbon, but may impact fish stocks or require population dislocation.
Negative externalities are dealt with by finding ways to include them in the cost of the product through regulation requiring that they eliminate the negative externality (e.g., sulphur scrubbers and low-sulphur coal for coal plants), or through market mechanisms which burden the cost of the externality and let people figure out how to deal with it (e.g., carbon pricing). In both cases, the cost of the negative externality needs to get added to cost of the form of generation so that market mechanisms can do their job, but in both cases, regulation is required in order to have that happen.
The best forms of generation today in this respect emit no CO2, particulate matter, NOx, hydrocarbons, or SOx during operation (e.g., wind, solar, geothermal, tidal, and nuclear). Large-scale carbon capture and sequestration has proven to be an economically non-viable pipe dream, as basic analysis of the underlying physics and economics made clear to dispassionate observers long ago, so fossil fuel generation will never be carbon neutral at any reasonable costs.
The best forms of generation today for negative externalities are wind, solar, tidal, and nuclear.
The wind doesn’t blow equally everywhere, but can be harvested in every country in the world economically. The sun doesn’t shine as strongly in Alaska as in Florida (or in Germany as in most of the US, despite what some people say), but is a viable resource in most countries of the world.
There aren’t effective sequestration sites under most parts of the world that would make it somewhat cost effective to put coal plants there and capture the carbon emissions. There aren’t good hydroelectric sites in many countries. Natural gas isn’t cheap everywhere. Landlocked states have no option for tidal energy. Islands have lots of waves, but less land and expensive grid connections, so wave energy starts to be viable. Nuclear is restricted to 30 or so stable regimes which are already part of the nuclear club, and expansion of the club is unwise.
What this all means is that there will be different mixes of generation that make sense in different places. This is mitigated massively, however, by the emerging continent-scale grids, high-voltage DC transmission which vastly lowers transmission losses, and energy markets. Basically, it’s getting easier and easier on more developed continents to generate electricity almost anywhere on the continent and get it to the major consumers at a reasonable price.
Given the above, in terms of broad deployment, the best forms of generation today in most countries of the world are wind and solar.
There are forms of generation which must run at 90% capacity factors in order to be economically viable (e.g., nuclear). There are forms of generation whose technology makes them very slow to respond to changes in demand or supply (e.g., nuclear). There are forms of generation which come onto the grid or fall off of the grid only in major increments of a GW or so, requiring substantial hot backups and contingencies (e.g., nuclear).
Then there are forms of generation which ramp up and down easily (e.g., wind, solar, gas, and hydro).
As economies develop, they go through a stage where 24/7 heavy manufacturing provides a very stable baseload demand which is easily met by inflexible generation. After that stage, they enter a consumer and knowledge worker economy where demand is much lower in the troughs and higher in the peaks. Too much inflexible generation, historically known as baseload generation, causes conditions of surplus baseload generation regularly for these economies. That occurs today in places like France and Ontario, with their large nuclear fleets, requiring them to pay neighbouring jurisdictions to take their electricity on a regular basis.
Given the above, on a flexibility basis, the best forms of generation in most places in the world are wind, solar, and methane generation.
Rapid to Build
There is a pressing need globally to decarbonize electrical generation, and in China, India, and many other places, to reduce pollution from electrical generation. A solution which takes 15 years on average to put in place from conception to commissioning (e.g., nuclear), isn’t a viable choice given the significance and urgency of the challenges. A solution which takes 1–3 years to put in place in utility scales (e.g., wind and solar) is much preferable.
Given the above, the best forms of generation in most places in the world are wind and solar.
Reliable & Predictable
A form of power which has a high likelihood of producing a certain number of MWh of generation in a certain period is reliable. A form of power whose availability can be determined with reasonable accuracy at longer time frames and high accuracy in shorter time frames is predictable. Grids require reliability and predictability.
Most classical forms of generation are reliable and predictable (e.g., coal, nuclear, gas, and hydro). Hydro is predictably better in the spring than fall, and reliable over the year.
New renewable forms of generation have proven themselves to be both reliable and predictable. Wind and solar are the fastest-growing forms of generation on every grid in the world today because they are sufficiently predictable and reliable that they do not destabilize grids in large volumes of generation. Their purported challenges in this regard are massively mitigated by wide area synchronous grids and markets. It’s only in isolationist and small grids that this is a challenge, but to be clear, there are enormous numbers of people living in archipelagos where this is a greater issue. High voltage direct current (HVDC) transmission offers a solution for archipelagos such as Indonesia due to its much lower losses underwater.
The most reliable and predictable generation in most places in the world today are wind, solar, hydro, nuclear, and methane gas. Coal is predictable and reliable, but at such great cost otherwise that it is impossible to recommend it.
Forms of generation which have operational or failure modes which cause massive economic disruption or health challenges, or which include potential for significant misuse of materials for terrorist ends, are high in liability in the event of a problem. Nuclear is the most obvious example of this, with very rare accidents on a per TWh basis, but very high impacts of those accidents. Fukushima is likely to cost closer to a trillion dollars (USD) for cleanup, economic disruption, replacement by expensive fossil fuels, etc. Coal has so many negative health and climate repercussions compared to alternatives that it must be considered a high liability form of generation.
The best forms of generation in most places in the world from this perspective are wind and solar.