Solar and Wind: Renewables alone not a substitute for fossil fuels.

At least, not alone. Solar and Wind have proven to be successful partial cost effective substitutes for fossil fuels, neither wind nor solar is stored energy. Without adding stored energy, available on demand, it is impossible to reach the goal of removing reliance on fossil fuels.

Consider home solar. With solar panels you can reduce your electricity costs, but to go ‘off grid’, you need a battery or other energy storage for the solar power.

The same applies at state or national levels, to go ‘off grid’ again requires batteries or other storage of the energy. This is an exploration of the barriers that mean the ‘green’ technologies like solar and wind, alone will never allow exiting fossil fuels for power. To replace fossil fuels for power, it needs storage, and we are not there yet.

Stationary Power: The Electrical Grid Needs Stored Energy.

The Grid: Driven By Stored Energy.

Ever since the days Pearl Street Station in 1882, our use of electrical energy has been based two types of power source:

  • predictable ‘base load power’: turbines providing continuous supply
  • on demand supply: a limited ability to provide increased supply at relatively short notice

Every technology prior to solar and wind fits with these patterns as they are driven by stored energy that consumed at the rate the power station determines.

Gas, Coal, Geothermal and Nuclear power stations all heat steam in order to drive turbines.

EIA
Even geothermal can look like it is polluting due to the steam.

Hydroelectricity is based on releasing water from dams to drive water turbines. All the heat/steam systems require hours if not days to start once shut down, leaving only hydro systems as particularly flexible. Starting turbines requires time and is costly, so turning turbines off comes at significant expense.

The turbines can be kept running at peak efficiency because the source of energy to power them is stored energy, ready for use as required. Gas and Coal are long term stored solar energy, converted from solar to chemical potential energy long ago, and accessible by burning the fuel. Hydro electricity is based on water with gravitational potential energy accessed by letting the water run downhill. Atomic energy is present in the atoms used as fuel and is accessed by initiating atomic reactions.

The nature of ‘continuous supply’ base-load power has made electricity less expensive during ‘off peak times’, as the electrical potential is available whether or not it is required.

Direct Solar and Direct Wind Power: Limited Replacement of Coal and Gas.

With solar and wind, the source of energy is not ready at the site of the generator waiting to be converted to electricity, but instead is immediate converted to electricity and supplied to the grid.

Having Solar and Wind that can generate enough power to match annual demands is within reach. What is not within reach is Solar and Wind generation that can deliver required power when it is needed, including at night when there is no wind, or other times of minimum generation.

Coal power- operating below capacity.

Because weather can be predicted with reasonable accuracy, the ‘base-load’ parts of the grid can have an advanced expectation of the power available from solar and wind, and can adjust their output, lowering their consumption of their stored fuel. This reduces emissions, but does eliminated coal and gas or the running costs.

There still may be some variability despite forecasts, so there will be times of excess power, when grids can lower their prices to enable customers who are flexible on when they use power to make use of lower cost power, but there is always some inefficiencies due to the need to allow for any difference between forecasts and real time power.

The biggest restriction is that there will be days when there is almost no solar power, and other times when there is almost no wind power. There is significant variation between ‘best scenario’ generation and ‘worst scenario’ generation from solar and wind.

It becomes necessary to design the power grid around ‘worst scenarios’. But what is worst given the nature of weather? Do you design around weather than may only happen for 10 days per year, or find another way to cope for those ten days? Can you cope if those ten days all occur at a similar time, which due to the seasonal nature of weather, can be very likely?

Provision for these worst cases means coal and gas that could otherwise be shutdown, can need to be still operational, and to be still operational, they often need to keep running even if at reduced loads, in order to avoid the shutdown and start-up processes.

Like with roof-top solar at home, without a battery, you can reduce electrical bills, but you still need traditional power. In fact the more people with roof top solar, the less that can be saved without a battery. When few other people have rooftop solar, you can sell excess power to the grid. When everyone else has rooftop solar, not only is there no longer a market for electricity on good solar days, the grid can longer cope with extra power put back by people and may need to institute penalties to stop overloading the grid with power that cannot be used.

These same scenarios have parallels on a wider scale for commercial solar and wind.

Energy Storage and the Grid: Challenges, but A Solution.

Having Solar and Wind that can generate enough power to match annual demands is within reach. It may seem that if sufficient storage could be added, then an entire grid from solar and wind would be possible. Although the fact that storage is never 100% efficient means that even more solar and wind would be needed, it is possible. If only we had that sufficient storage technology.

Update: As discussed in this you tube video (at the linked point at around 40 minutes) that is pro-renewables, without storage, the problem is not solved.

Powered Vehicles: Leading the way on storage technologies.

A Long History Of Direct Energy.

Vehicles have a long history of perfecting methods to deal with the unreliability of direct wind energy, and more recently with solar energy in the World Solar Challenge. Even in the air, gliders can operate on direct energy from air movement, but like sail boats and solar cars, the use of direct energy from nature is relegated to recreation and competitions.

Stored Power Quickly Overturns History.

1819: The first ships that were built using steam power began to cross the Atlantic Ocean. Steamships used a combination of wind and steam power to move.

1845: It was in the mid-1800s that the first ocean liners built from iron began to appear. The ocean going liners were also driven by a propeller instead of sails like many earlier ships.

1880: River boats that were driven by steam were called stern wheelers. Other similar boats featured paddle wheels on each side and were called paddle steamers. Paddle steamers were mainly used for transport on rivers.

1910: Ships that were previously powered by burning coal started to be converted to diesel power, and started to use oil as opposed to steam.

A TIMELINE OF SHIPS, BOATS, AND YACHTS

It took less than 100 years to complete the progression from wind to stored energy in vehicles, and there is no sign of any return to some form of direct energy.

Overwhelmingly, commercially viable vehicles rely on stored energy.

Vehicles: Necessity drives Innovation.

In fact the race to power vehicles with alternatives to fossil fuels has, in contrast to the electrical grid, focused on alternative stored energy, and not the source of the energy itself. So while the electrical grid has focused on sources of energy: Hydro, Nuclear, Wind, Solar, Geothermal etc, the motor vehicle industry has focused on how to store energy: Batteries and Hydrogen.

As a result, batteries from Car companies such as Tesla have found their way into the electricity grid. Hydrogen cars look like losing out to batteries in cars, but the technology developed could find its way into aviation and shipping.

Storage technologies.

Batteries.

The prices, weight and size of batteries for a give storage capacity has been dropping.

The fact that energy can be stored in batteries is well known. 🙂

Green Hydrogen (not to be confused with blue Hydrogen).

Hydrogen is an much hyped, and often misunderstood, way storing energy as explored in more detail in a separate exploration.

‘Green’ hydrogen is the use of hydrogen for storage for ‘green’ energy, in order to produce a reliable, available on demand source of energy from by Solar energy and/or Wind power.

‘Blue’ hydrogen is where fossil fuels (mostly gas), are used as a source of hydrogen. The resulting hydrogen is a ‘clean’ fuel, but the same amount of CO2 as using fossil fuel is produced at the blue hydrogen factory. Many see ‘blue’ hydrogen as an attempt to ‘greenwash’ the use of fossil fuels.

In contrast to pumped hydro, Hydrogen storage does not require any particular terrain and can even be stored underground and in locations such as a dessert, or abandoned coal mine.

Pumped Hydro.

Conventional Hydro-Electrical Generator.

Most of us are familiar with Hydro-electricity. The principle is a dam is used to contain water at raised altitude (an upper reservoir), allowing energy to be obtained by turning a turbine as that water flows to a lower altitude. The spinning turbine is used to produce electricity.

Having large volume of water available by either having a dam or simply a large water body at the point of discharge (a lower reservoir), adds the ability to store energy from the grid for later use by using energy to pump water back uphill into the original raised altitude dam.

Pumped Hydro has been in operation at Ffestiniog Power Station in Wales since 1963. The first pumped-hydro implementations were designed to provide power in the event of an outage of the normal power source, typically a coal-fired power stations, and were designed to provide power until operation the of the normal power source could be restored.

Snowy Hydro ‘Snowy 2.0’ in Australia.

Newer pumped-hydro systems are designed around the provision of power during both daily and longer term periods when Solar and Wind systems cannot deliver power at required levels to the grid. This means the new ‘pumped-hydro’ operations are designed to be supplying power far more often than older designs.

Pumped-hydro can have huge capacity, but can only be located in locations where there is a water supply, evaporation is not excessive, and there is significant changes in elevation.

Stored Heat.

The Sun provides heat, so why not just store that heat? The simplest storage of solar energy is to just capture the heat, which is exactly the technology of the first ‘home solar’, which was ‘home solar hot water‘. As solar cells dropped in price and became more efficient, solar hot water has become an outdated technology. There are other limited applications of storing energy as heat, but it is generally for more efficient to store electrical energy, and solar cells are now more efficient than heat capture.

Stored Mechanical Energy.

Another way of storing energy for later use is to store the energy as mechanical energy. This is of most use when the energy being stored is already mechanical energy, which is not the case with solar, and while it could be used to store energy from a wind turbine, I have not seen any practical use with wind energy either. Formula one cars store mechanical energy in a flywheel using a Kinetic Energy Recovery System, KERS but there is very limited use of flywheels for storage as friction limits them to short duration storage.

Alternative: Storage free ‘Green’ predictable energy.

The Alternative to adding storage to get around the problems of the variability of Solar and Wind power, is to use alternative energy sources that are reliable from the outset. Note that while reliable power vastly reduces storage capacity required, stored energy is still solves the problem of storing excess capacity in times of lower demand, and delivering extra capacity in times of peak or unexpected demand. Almost all power generation other than hydro or storage, are limited in their ability to be ‘turned down’ for low demand or ‘turned up’ for extra power.

‘Green’ Fission: radioactive material can be eliminated, but at a cost.

The nature of atoms is that the process of converting any atom with a larger number than Iron into a smaller atom still larger than Iron, a process known as nuclear fission, produces enormous amounts of energy.

How stuff works: Nuclear Power Plant.

Nuclear Fission has three major problems:

  1. It is difficult to keep under control.
  2. The easiest ingredients to work with are dangerous radioactive materials with long half lives.
  3. The products of reactions are more dangerous radioactive waste also with extremely long half lives.

The website ‘how stuff works’ does a great job of explaining how current Nuclear Power Plants operate, so I do not need to repeat their work.

Chernobyl and other accidents have demonstrated the reality of problem number 1.

What is not explained on the ‘how stuff works’ site is that U-235, the main fuel and Plutonium-239, the main wastes for these plants, have half lives of 703.8 million years and 24,110 years respectively. They leak radiation for a long time. The biggest concern is the waste, because if all goes well the fuel will be used, but what do you do with all that waste?

The reality it is possible to use particle accelerators to reduce nuclear waste to non radioactive elements, but it is expensive. You can also start with non-radioactive elements, but the process becomes far more difficult, and again, far more expensive. The reality is that while you can technically make nuclear fission reactions waste free, they are simply not commercially competitive if you do. Profit before safety and sustainability.

Clean nuclear: Fusion.

The nuclear alternative to fission, splitting big atoms into smaller ones, is fusion, which is joining smaller atoms into bigger ones. It may sound strange that these two opposite processes can both generate masses of energy, but they can. Why not go back and forth, big to little and back? Because it is not all fission or all fusion that generates energy. Fission generates energy only as long as the atoms are bigger than Iron, and fusion generates energy while the atoms are smaller than Iron. With both processes, it ends at Iron, which is one reason there is so much Iron.

Nuclear Fusion or Hydrogen into Helium, the same as the main process powering the Sun, not only generates massive energy, it also is free of radioactive waste!

The problem is, for nuclear fusions, you need enormous temperature and pressure, and creating enormous temperature and pressure requires a lot of energy. So far, there are no working reactors that capture more energy than is required to make the reactions happen. It is being worked on, and is technically solvable, but we are just not there yet.

Biofuels.

Bio fuels are using solar energy to directly produce store energy such as sugars or alcohol. The problem is you need water and time as well as the solar energy, and unless you use prime farming land, solar energy and generating hydrogen is more efficient.

Tidal, Geothermal.

Tidal and Geothermal both work only in specific locations. I could be wrong, but I see them as potentially cost effective contributions to the electrical grid, but their role is more determined by the specific geography and availability than the desires of governments or energy companies. This makes them great in some places, but difficult to scale to provide a large percentage of energy requirements.

The Economics of Solar and Wind plus storage.

Storage: An Added Cost to deliver dependability.

After considering all the alternatives, Solar and Wind are the most attractive source for new power generation. They generally produce the most cost effective power available today, if only they can be made dependable.

Enter storage to solve the dependability problem. But is Solar and Wind still economically attractive once you add the cost of storage? That becomes the big question.

The first step has been solar and wind that reduce use of fossil fuels. Once you move into storage, the cost of the renewable sourced energy is increased, making it less competitive with using fossil fuels. However, there is another payback, with enough storage, you can close down fossil fuel power plants, saving more than can be gained by allowing the fossil fuel power plants to run at a lower output when solar and wind are available and thus reducing the amount consumed and some of the cost of fossil fuel. Without storage, the old plant is still needed for when there is less wind and solar, but with enough storage, you can progressively reduce the number of traditional power plants.

The Economics of providing All Power Generation.

With every power system there is an initial capital outlay which has to be amortized over a number of years, and once amortised, only operation and maintenance costs must be covered to reach profitability.

Most coal plants in developed countries are old enough to have already recovered the initial capital costs, making power from an existing coal plant much less expensive than new coal plants.

Replacing Older Power Plants: The Economic Payback From Adding Storage.

Storage has the potential to reduce costs to a network for an overall cost saving. Electricty supply can be less expensive as a result of adding storage, so storage is not simply an extra cost, but an opportunity for cost savings.

Adding storage has the potential to remove more costs than the cost of providing the storage itself, creating a financial return. The cost savings adding storage, is that having reliable power enables retiring other, older, often coal powered power plants. Having reliable power enable removing the costs of plant operation, maintenance and the fuel costs, from plants which need to at least be on standby if the only alternative is direct solar and/or wind power.

Being able to shut down older plants becomes most attractive when there are power plants of an age where a new, replacement power plant is required. New coal/gas power plants, with a new period amortization of the costs of building the plant, can be one the least cost effective options for new power.

Why was storage not provided with wind and solar from the outset?

There are three main reasons:

  1. There is little point providing power storage when the power generation is still unproven.
  2. There was no requirement for the power storage until solar and wind power was in place generating the need.
  3. With no requirement for storing power until recently, the technology was not ready, or even developed.

This means, even now, many power storage options are on a steep learning curve. For example, there is significant investment in Hydrogen storage as while less efficient than battery storage, it can be scaled to capacities where batteries would always be too expensive, but at this time it is investment, not yet deployment.

Coal, Oil, Gas post ‘Fossil Fuel’: Not Dead Yet.

Just as stones were still used after the stone age, copper was still used after bronze age, and horses still used in the age of motor vehicles, Coal, Oil and Gas will still have uses even if/when we get to the point of storage or other technologies bringing an end to their uses as fuels.

From plastics, to fertilizers, to bitumen and coking coal, there will remain uses of fossil fuels for a long time. Some of these other uses are also problematic, but it we stop using them as fuel, then the CO2 risk may pass.

Another reason fossil fuels are not dead is because of the economic and resulting political power behind them.

Conclusion: Solar and Wind Can end Fossil Fuel Age, but only when we have storage.

Solar and Wind are booming for energy generation. But just because countries like Denmark who have reached 50% of energy from Solar and Wind, does not mean they are half-way to all solar and wind.

No amount of Solar and Wind alone allows turning off fossil fuel power plants. But Solar and Wind combined with storage does allow replacing fossil fuel power plants, with the potential to reduce prices and have a supply more reliable than ever.

This makes Solar and Wind just the first step on a journey. A journey that requires the addition of a new ingredient before reaching the end goal. The end goal requires adding storage, and will take time, . Much of the technology requires improving what has been done before and can required development time.

Adding storage can provide a solution and is feasible. It has even commenced in many locations, but it will take many years to achieve what is needed.

Critics of Solar and Wind raise a valid point when they claim Solar and Wind cannot replace fossil fuels. Yes, but Solar, Wind and Storage can replace fossil fuels.

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