Intermittent Energy – A New Paradigm

We live in a time where change is needed – quickly.  Many politicians and renewable advocates seem to think that a wholesale change from fossil fuel to renewables is essential, and many would like the nuclear capacity removed at the same time.  The most recent reports suggest that this change needs to be well underway, and the emissions in significant decline within 11 years.

The numbers present a challenging picture.  In 2017 in the US, fossil fuel provided almost 80% of the total primary energy, while solar and wind contributed approximately 3% of the energy.  In Canada, in 2016, solar and wind provided only 0.5% of primary energy, while fossil fuel provided over 70% of primary energy.

Nonetheless, the targets are set, and many people and governments are seeking to displace ALL fossil fuel with renewable energy.  The results, to put it mildly, are bordering on dismal.  Canada has set targets that are ambitious, and seems to do relatively little, other than to talk about meeting the challenges.  We are far behind in our targets for reduced emissions.

I see people spending large quantities of money on rooftop solar, assuming that they will reduce their costs and save the planet.  At the same time, I see utilities in trouble, both operationally and potentially financially, while doing their best under current methods to accommodate, and in fact, to encourage this concept.

As James Avery, a senior executive at San Diego Gas and Electric said, “Customers are often trying to do the right thing for the environment by going solar, but they aren’t being incentivized to do the right thing for the grid or for their neighbors. Today, one set of customers is subsidizing another to the tune of more than $100 million per year.”

But at the system level, I also see real problems.  Intermittent sources are just that, and in some cases, the power available is difficult to predict.  The utility is expected to provide a reliable and firm source of power at all times.  People suggest that batteries will do that task, but it will likely take more than that.

From a 40,000-foot look, the utility is designed to work well, but there are a number of standards that have become the established norm for over 100 years:

  • The sources of power are dispatchable – they can be started and stopped according to a plan, and the output can be reliably managed. The utility expects to be able to fully control the power from almost any generator that is connected to their grid.
  • The load, on the other hand, may be intermittent, random and may be applied or removed at any time, without advance notice or warnings.

The system has worked well with this concept, and utilities have been able to manage economically while providing a reliable service.

The introduction of intermittent renewables has caused a little confusion.  These sources are generators, but in fact they act in the way that a load is assumed to do.  They are relatively random, and intermittent, and yet people want to run them as a generator that is “supposed” to be fully dispatchable.  That does not work within the current method of operation, and the results are visible.

But, in fact, the current system has other issues, and a good look from far above may produce a system that can accommodate a high level of intermittent sources and cure some other issues at the same time.

The existing system is not all that efficient in its methods of operation.  Utilities have developed very sophisticated systems to get the best out of their system, but there are some inherent issues:

  • Under the existing concept, when generators are run up and down during the day, as they must do to match a demand that has a wide range over a day, the generators are operating at less than maximum efficiency for much of the day. This may be either a large or a small loss, depending on the generator.  Some utilities have used market sales to other utilities to smooth out their operation and gain efficiency.
  • The transmission and distribution systems have a similar problem, in that the loss increases with the square of the current, so if you double the current to meet peak demand, the loss goes up by 4x.  It is more efficient to operate at a constant level.
  • The grid is designed to meet peak demand – an event that lasts about 15 minutes once annually, and perhaps not at all. The average demand on the grid is about half of the peak capacity that is available, and the system design is largely based on meeting peak demand. The addition of solar generation has reduced the mid day energy sales in many utilities, but the peak that occurs after dark, is continuing to grow, requiring added expense while the utility revenue may be falling as energy sales decline.  This is leading to some rate changes that may impact the financial viability of home based solar systems.
  • The addition of large amounts of solar generation result in very rapid changes in demand seen by the utility as the sun rises and sets, and this results in a need to use generators that can ramp up or down very quickly to match the change. Generally, this is not the lowest cost generation. So the utility is essentially experiencing higher costs as a result of the rapid changes in demand caused by increased penetration of solar systems.

There has got to be a better way – to run the grid, in a way that will get maximum efficiency on a continuous basis, deliver more energy, smooth the variations in the demands on central generation, and on the delivery systems, meet the needs of all customers, AND accept a large and growing component of intermittent generation.

The key seems to be that a major part of managing the grid will have to move from the “top” (Central generation) to the “bottom” – at the grid edge near the loads.  If the demand on the central generation and delivery system can be managed to be near a constant, the system could deliver almost double the energy that is delivered today and could operate at a  much better level of efficiency.

There are many people that have suggested to me that the central utility will soon be redundant.  I would strongly disagree with this concept.  The electrical grid currently delivers about 20% of the total energy.  I hear many people that think that if they can displace all of their utility supplied electricity, that all problems will be solved, but they seem to neglect the other 80%.  We need to include heating for buildings, fuel for our vehicles, and potentially a lot of other energy that will replace processes that currently rely on fossil fuels.  I would need enough energy to collect more than double my current electricity consumption to fully address my energy use, and that does not consider the fuels used to provide the services and supplies that I need.

What is needed is a long-term transition plan and short-term targets to capture the “low hanging” opportunities.  For example, the largest source of emissions in the US is the generation of electricity from coal.  This is a little frustrating as that one large source provides less than half of the primary energy to generate electricity.  And that electricity delivers only about 1/5 of the total energy used.  In other words, the biggest source of emissions is delivering only about 10% of the energy needs.   It seems obvious that getting rid of coal generation would be a very big first step in cleaning our air.  The longer term can then focus carefully on what can be done at the grid edge to accommodate more intermittent energy, smooth the demand and yet maintain stability and reliability.

There are real challenges ahead, but the ideas currently promoted by many politicians – get rid of all fossil fuel NOW and replace it ALL with intermittent sources is not going to work.  We need a plan that will meet the energy needs going forward, and a transition that will reduce the major sources of emissions quickly.

Energy Puzzle – The Missing Piece

I just saw Dr David Suzuki on TV claiming that we should build no pipelines – and get off fossil fuel.  I remember him well, when I was a student.  He was a well-respected expert professor in genetics at the University of BC in Vancouver and he was best known for his work with “fruit flies.”  As an engineering student, we all used to crowd into his final lecture each term and listen to him talking on a subject that he really knew well – the risks of “genetics engineering,” and the problems that it could lead to.  It was always spell binding.

Over the years Suzuki now seems to be viewed as an expert on energy, and yet, the papers claim he owns large houses, and drives an SUV.

We have real problems with climate, fossil fuels, and carbon emissions, but one needs to look carefully at what we face:

  1. The biggest sources of emissions in the US are the generation of electricity from coal, and the transportation industry (60% of which is for personal transportation). These two sources are responsible for more than 2/3 of the total emissions.  Canada is only slightly better, in that our electric system generates almost 60% of total energy with hydro and nuclear is a large contributor to clean electricity as well.  Our petroleum industry ranks second, behind transportation.
  2. Electricity provides less than 20% of total energy, the remainder is almost all fossil fuel. The average person gets fuel in three forms; electricity, natural gas, and transportation fuel (gasoline or diesel fuel).  Any major reduction in the direct delivery of fossil fuel will be expected to be replaced with electricity – and that may be a big challenge, given the fact that the electric grid at present delivers only about 20% of the total energy.
  3. Many people seem to think that if they can convert their current electricity use to solar energy, that the problem will be solved, but they tend to forget about heating and transportation fuel. In most cases, the fossil fuel energy is far larger than the electrical energy delivered.
  4. I keep hearing that the problem is someone else’s fault – Blame India, China, the oil industry or the government. We all need to look in the mirror – and see the big users.  North Americans are among the largest users of energy per capita in the world.  As “Pogo” would have said ”We have seen the enemy and it is us!”

There are two areas to look at; the supply of energy, and the use of energy.

Perhaps it is time for some real rational thought and a list of priorities, NOT aimed at eliminating fossil fuel in the short term but going for the “low hanging fruit” and hit emissions where they are worst.  We need some fast progress on items that can have an immediate impact.

The generation of electricity from coal is a great example.  Coal fired generating plants are about 30% efficient, largely because of the Rankine Cycle that they use to operate.  But coal also produces double the emissions that the same energy from natural gas would do.  Technology to use natural gas to generate electricity at much higher efficiencies exists.  A combined heat and power system (burns gas and delivers electricity, heating and cooling) may be more than 85% efficient – potentially reducing emissions by almost 90% if it is located in an urban area where the heating and cooling are used, and delivery losses are minimal.

Solar and wind are widely perceived as the perfect solution, but there are integration and intermittency issues that must be addressed.  California has found that it must keep conventional generation running to address needs after sunset.  Solar generation during the daytime, when demand is low, is causing a challenge.  California is apparently PAYING other utilities that have capability for storage or more flexible generation, to TAKE their surplus, only to buy it back a few hours later after sunset when needed.  Ontario, where a large program for wind was established by government, now has a Surplus Baseload Generation issue, where they have been heavily restricted on where and for how much it can be sold.  The result, some of the surplus is discharged as steam into condensers at a nuclear plant and discharged into Lake Huron. This is called a “nuclear maneuver” and candidly, the utility seems to have no alternative – this has been decreed by the politicians.

So, we are being driven by people like Dr Suzuki to eliminate all sources, and that will solve the problem. He forgets that this will do little to the demand and may well result in higher taxes and  higher energy prices for energy as it becomes scarce.  Our major sources could become offshore countries with little environmental protection.  The demand needs to be addressed immediately.

There is some good news that is taking place. The British Columbia Government has implemented a ” Step Code” for new construction.  All new buildings will be much more efficient than old buildings.  But that is a slow process because the turnover of buildings may take many decades.

Demand is another issue.  I drive by our car dealerships each day and I see nothing but big huge trucks. We need to have a good look in the mirror and start making some lifestyle changes.

On a structured basis, I see several needs:

  1. Eliminate or reduce coal use – and if needed, use high efficiency natural gas for heating.
  2. Take steps yourself to reduce energy use. There are lots of opportunities:
    1. Insulate your home well – there are almost always some things that may make a big difference – get rid of the old lights and replace them with LED lights… install an HRV (Heat Recovery Ventilator), use curtains or blinds to contain heat at night etc. Install a heat pump – the current electric rate structure mandated by government makes heat pumps uneconomic, but that will have to change.  I have a dual system – heat pump/high efficiency natural gas.
    2. Get rid of the truck or SUV and drive the smallest car you can justify. We used to have 3 cars and now have only one EV which we have had for more than one year.  In that time, we have driven 20,000 km, and the car has been in for service once – to change the tires (winter tires) and upgrade the software – maintenance is almost zero and fuel costs are about 1/5 of what I paid for gasoline.  In addition, many chargers are free.  The parking lot across from our favourite restaurant is equipped with 2 free chargers.  We get the equivalent of $10 in gasoline for free, while we enjoy the best Italian meal in town.
  3. Do not participate in opposition to natural gas exports. Much of this is destined to replace coal, and that is a very positive move.  It also helps to keep our taxes down.  Know the facts before standing up against anything.
  4. Be prepared to listen to real experts on energy. There are plenty around that really understand the options ahead and are not fixated on stopping all projects as Dr Suzuki attempts to do.

We need to move quickly to cleaner energy – this means a transition – not a step change.  It would be nice to survive this change, and not be bankrupted by heavy taxes and higher cost energy when demand is essentially left untouched.

Everyone seems to like to blame the oil companies and the electric utilities for the problems.  These are the people that deliver the energy.  WE are the ones that use it.  Some of the utilities and oil companies have innovative progressive initiatives. Here are a few examples:

  1. Shell has tied executive salaries to emissions – both inside their company and by the users of their products.
  2. Our local utility FortisBC has funded an Energy Chair at the local university and is looking at using surplus electricity (that others sell at negative prices) to make hydrogen.
  3. Portland GE has implemented systems that control demand – with a very large number of behind the meter loads – this reduces peaker starts, reduces emissions, and reduces system losses.
  4. Tesla, with their EVs and batteries have driven the sales of EVs far above most expectations and have brought the cost of batteries down to the point that they may be very cost effective in grid applications. They are involved in a large project, that my company is also working on, to provide similar savings, emission reductions, losses, and integration of intermittent generation.

And what are the users (That is US) doing?  For the most part, we are protesting, complaining, and blaming others for the problems ahead.  Dr Suzuki is probably one of the best examples. He is a smart man in genetics, but he lives an energy intense life and blames others.

We need a little change of attitude here! (In my humble opinion).

Hydro and Wind Capacity Factors

I enjoy looking at statistics on wind turbines. Typically, I hear that a turbine will produce enough energy for a certain number of homes… and then I hear the wind advocates telling others that their capacity factor is as good or better than hydro… and in some cases, it actually looks like they might be right. But there is a very large difference between the capacity factor of a hydro plant and the capacity factor of a wind turbine or solar collector.

I saw one statistic that suggested that a wind turbine might have an average capacity factor of 30%… A 3 MW wind turbine would generate about 7,900 MWh in a year. That SOUNDS like a lot of energy, but in fact, if you assume that the average home uses about 10 MWh per year, that is enough energy for about 790 average homes. That amount of energy provides a North American home with electricity for most needs, but generally does NOT include heating, which more often uses a fossil fuel such as natural gas.

But the number also ignores a few facts. The wind turbine does generate enough annual energy for 790 average homes, but is it there when needed?  As an extreme example, if the wind blew and the generator operated at full power continuously for 1/3 of the year, and did not operate at all, outside those times, there might be a serious problem. Those homes would have power to spare for a part of the year, and none for the other larger part.

But batteries are supposed to be the solution! If one assumed that the turbine ran 1 full day, and then not at all for the next 2, it would have a capacity factor of 33%, and that might need a very big battery… in fact, in one fill day, the turbine would generate 72 MWh, and the homes around it might use about 1/3 of that – leaving a surplus of 48 MWh for storage for the following 2 days. The cost of a battery, at current prices for that amount of storage would be (based on $200/kWh) almost $10,000,000, or a capital cost of about $12,000 per home.  That price is expected to drop, but it might go down to about $5,000/home by 2025.

But again, that misses a few factors…

First, the wind is not fully predictable in the longer term. Much of the time, it may be far better than a day on and two off; blowing for at least a few hours every day, meaning that the battery might be smaller, but on the other hand, we have all seen the hot summer days in the summer when there may not be a puff of wind for a week, meaning that it also might need to be a much bigger. The message  here is not intended to degrade wind, but to make it clear that there are challenges that can be overcome to store and use the energy more efficiently.

The real issue for emissions is the fact that this ONLY converts the existing household electrical use to renewable power. The two biggest sources of carbon emissions are electricity generation (largely coal) and transportation (60% personal vehicles), What about the heating, and fuel for the car, plus all the energy needed to supply goods and services for all that we all need to live. The bad news is the fact that the existing electric grid only supplies about 1/5 of the energy that we all use. The balance is almost all natural gas, gasoline or other fossil fuel. We use a lot of energy, and we are all accustomed to turning up the heat when it is cold…. driving to town for dinner or a night out, or a vacation to the beach a days drive away. A battery to smooth the needs for all use might cost much more. One problem that most of us face is a seasonal variation in fuel use. In my case, I use almost 75% of my annual energy between November and late March. Air conditioning, believe it or not, is actually relatively efficient. Solar energy is heavily biased to arrive in summer months when it may be needed least. Storage from summer to winter is a real challenge.

A hydro plant, on the other hand is a little different in its operation. It can be turned up quickly if needed, and shut down just as quickly if the power is not needed. In the years before about 1950, many hydro plants were built, based on “firm power capacity” and that meant that they could generate their maximum power virtually continuously for an entire year. There were times that water spilled over the spillway, and other times when it did not. But the plant could generate continuously and provided a reliable source of energy for the customers at the time.

In recent years, with all of the interconnections between utilities, and the wholesale trading that goes on, some smart companies have bought a bunch of old hydro plants and replaced the generators with much larger ones. These companies can now store water behind their dams for much of the day, simply by not using the water for generation, and not spilling it. This happens when market prices are low, but when the wholesale price spikes during peak periods, they can generate an entire days worth of energy in a few hours, and they make very good money in doing just that. This type of operation appears to have a low capacity factor, as the generators only run when the prices are high. The key is that an operator can choose when that is needed, and is not forced to wait for wind or sunny weather.

One example that comes to mind. As a student, I worked at a hydro plant on a river that is a tributary of the Columbia River. The dam had a height of over 200 ft, and a forebay behind the dam was only about 5 miles in length. It was a raging torrent of a river before the dam was built – dropping over 400 ft in the 14 miles of river that is in Canada.Capture

When first built, the plant was equipped with two generators – 90 MW each, but the powerhouse was equipped to accommodate 4 generators. In that plant, the 2 generators could run almost continuously at 180 MW with a few short periods, when flows were very low, that capacity might be reduced to 150-160 MW. But for almost half of each year, the spillway discharged much more water than was going through the generator turbines.

After a few years later, my employer signed an “equi-change” agreement with another utility that had opposite capability, or storage. Soon, two generators were added, and for half of the year, we ran 4 generators, and exported the equivalent of 1 generator, while for the other half of the year, we ran 2 generators, but imported the equivalent of 1 generator. We had a plant that provided about 270 MW of firm power.

You can imagine my surprise a few years ago, when I learned that they were building an extension to the plant, that would generate a further 335 MW of capacity. The total capacity, after upgrades to the existing powerhouse totalled more than 700 MW. I wondered how they would ever make that pay, as there were only a few weeks each year when there was enough water to generate that much power. Graph

It didn’t take long to find out what they were doing. When I worked there, I became an operator, and we were always careful to keep the forebay at a constant level – as high as possible, to get the most power from every bit of water than went through the turbines. We were rarely down more than an inch or two from the full pond level.

I can now see the forebay level on the internet, and what has happened is remarkable. The graph shows the forebay level over a 2 day period, and one can see that they are using the storage behind the dam, small as it is, to generate energy for peak periods and store during off peak periods. The old generators and turbines have been  upgraded and the plant now has a firm capacity of as much as 200 MW, but the capacity is over 700 MW. For those in the US, the readings are in M, (1 M is a little over 3 ft) so the forebay level was run up and down by more than 6 ft in 1-2 days. So much for our 2 inch limits. The average capacity factor is far less than 50%. The wind advocates may want to claim that their wind turbine can beat this… but there is one key difference. This capacity is fully dispatched. It can be called when needed and stopped – to store energy when not needed. They generate when it makes economic sense, and reduce capacity dramatically when prices are low. What is interesting is the fact that this plant has a small reservoir (5-6 miles in length) and the storage in that forebay has justified the construction of a second almost equal capacity powerhouse that cost almost 30 times the total cost of the initial dam and powerhouse.

Most hydro plants are now built with far more capacity than they can run continuously, but these plants can all be dispatched when and as needed. In this way, they are very different than wind or solar. The key difference is that they can be dispatched at any time to whatever capacity is needed, provided there is water available behind the dam.

What is really needed is a way to have the intermittent generators work in an optimized way with plants such as hydro that can be dispatched, to get all of the energy that we can get from the renewables, and store it efficiently. This form of storage is near to 100% efficient. I would suggest, that most of these plants were built, based on the value of the energy produced and not on the storage provided. The storage is almost free. The picture is now rapidly changing and storage may soon have much more value than the energy generated.

And that brings up the real definition of storage in the grid. Electricity used to be used in the very instant that it was generated. Storage allows the separation of the generation time and the consumption time.

There is a great future for batteries, but they remain a dedicated, and relatively costly device. There are many other forms of storage that can be leveraged; devices that were bought and paid for to provide another service, much like the old generating station, that can be used to do the same thing, but at the grid edge, where there is almost no energy loss between a storage device and the load the process may be even more efficient. We see the rapid advance of Virtual Power Plants (VPPs) that manage a wide variety of devices that can effectively deliver a large impact from many small storage devices, such as domestic water heaters, EV chargers, air conditioning units, water pumps etc.

We are entering a time when the entire grid operation will need to be optimized to gain maximum benefits from every source available, including the most intermittent sources, and the VPP will play a huge role in this. Some utilities are currently participating in imbalance markets that match shortages with surpluses. But this will need to grow to include behind the meter devices. The missing link may be the need to have all players around a single table, all agreeing to solve the problem in the best way, and a means to fairly share the benefits.