Analyzing the Costs of Fossil Fuels Vs. Renewables
In response to my post How Much Renewable Energy Does the World Really Need? frequent commenter Steven Andrews writes:
I think THIS is the way to go. First, install all the renewable energy you can with the capital you have, because you don´t need to pay for fuel (which always tends to cost more) so you save on fuel; then you keep on investing in renewable energy, until one day, you produce more energy than you need and start exporting it!
While I applaud your enthusiasm, Steven, I need to point out that, unfortunately, you are confused about one of the distinguishing aspects of the financial costs of fossil fuels versus renewables. It’s true that the fuel that drives renewable energy is free (for the most part). Thus the economic benefit associated with that is realized over a long period of time — not at the onset of the project. The opposite is the case with fossil fuel plants, where the cost of operation is largely based on the fuel, and is thus stretched out over the life of the plant.
This is a regrettable but unavoidable fact of the matter.
But don’t let that dampen your spirit; there are dozens of other issues that make this a far more interesting and complicated discussion.
The other problem is that when you have the power available to export is not necessarily the time there is a demand for the power. And, when you have no power to export, the demand may be very high.
We are a very long way from having enough renewable energy for intermittency to be a major problem, and even in Germany, there have so far been very few problems with around 32 GW of wind and 32 GW of installed solar capacity.
(One sunny Sunday last summer, solar power provided half of Germany’s total power consumption).
Even larger renewable capacity can be added using thermal storage when there is excess power – to store up both heat and cold to meet heating and cooling loads as and when required. In large systems such as district heating and large building air conditioning systems, it is possible to store heat or cold for weeks or even months at an economically viable cost – with the store acting as a buffer to level out much of the variation in intermittent electricity output.
By introducing electric vehicles in large numbers, it becomes possible to add even greater buffering capability and to further reduce emissions.
Thermal storage is not for PV solar systems which is the most common type of solar system for generating electricity. It is true that thermal storage will work for systems using concentrating solar collectors to heat a fluid which can be used to heat fused salt tanks (containing a mixture of NaNO3 and KNO3) to store energy thermally for later conversion to electricity, but there is a limit to how much storage is practical. So far as I know, no system built has sufficient capacity to store heat for more than one day of power generation. Not also that concentrating systems will not work on cloudy days; they require direct sunlight which, in Germany, is in short supply.
It is possible that EVs could provide sufficient storage to make intermittent sources of power more practical, but it is too soon to know whether EVs will ever be manufactured in sufficiently large numbers for that to happen. The consequences of continuing to emit large amounts of CO2 are likely to be so great that it would be unwise to rely on something that may never exist.
“(One sunny Sunday last summer, solar power provided half of Germany’s total power consumption).”
I don’t doubt that, but Germany has more cloudy days than sunny days. If it could generate that amount of power for only one day during the summer, that certainly does not look promising. Their PV panels will work even on cloudy days, but the power is greatly reduced when direct sunlight is not available.
Since deciding to phase out nuclear power, Germany has increased the amount of nuclear-generated power it imports from France. It has also increased the amount of lignite it burns to generate power and plans to build more lignite burning power plants. The result is that its CO2 emissions have increased and will continue to increase. Moreover, lignite is an especially dirty type of coal.
It is likely that within five years, Germany will do a complete about-face and decide that nuclear power is the only solution to its power requirements.
Unfortunately, during the Clinton administration, a decision was made to halt funding for nuclear R & D, the reason given was that more R & D was not needed. Had that R & D not been halted, it is likely that we’d have a better, safer, more economical nuclear technology available for implementation right now, and it would generate less than 1% as much waste as our horrendously inefficient pressurized water reactors generate which extract less than 1% of the available energy from the nuclear fuel. Enough work has already been done to prove that far better nuclear technologies are possible.
From all the evidence I’ve seen, an improved nuclear technology is the only energy source that will solve our CO2 emission problems without forcing us to live in a way that would be politically unacceptable.
My reference to thermal storage is not to high temperature thermal storage for power generation, but rather to sanitary hot water and stored cooling allowing the timing of electricity consumption to be shifted and moving peak loads to when intermittent generation is able to supply the load.
Where you have a large district heating system – common in Germany and most of Scandinavia, it is possible to use very large scale thermal storage combined with ground source heat pumps – using two arrays of boreholes to store heat on one side and cold on the other in large volumes of soil and rock. Heat can be stored right through the summer for use in the winter, and also the reverse storing winter cold to cool buildings through the summer.
When the majority of thermal load is met in this way, fossil fuels are displaced from their traditional role in heating, and a large proportion of electrical load can be moved to convenient times rather than having to be met when heating or cooling is used – so greatly reducing the need for fossil fuels in a spinning reserve role.
That type of thermal storage is practical and probably should be more common.
When my new house was in the design phase, I considered a geothermal heat pump, but the cost would have been excessive.
When I lived in Fiji (1994 – 2004), solar water heaters were common except in rental units where the owner did not pay for the water heating. Mine had a electric booster which I could turn on if necessary, but it was rarely needed. Solar water heaters could make sense here too.
PV systems are generally less than 20% efficient whereas collectors for heating water generally exceed 50% efficiency. Solar space heating can also make sense.