Category Archives: electricity

Firming Things Up

One of the big issues with renewables is the need for firming – production is intermittent while needs are more or less on a curve matching the human activity curve. Solar is a good match for air conditioning and heating in areas that are cold and sunny, hydro at large scale is good for dispatchable generation and can also serve as a baseload source in the right situation. But wind is famously finicky. So this article on compressed air storage is pretty exciting.

Hydro systems are often paired with pumped storage, where reservoirs are filled when power is available and used for peak generation, now Hydrostor is combining air and water for storage. The combination of wind, water, and suitable heights for pumped storage aren’t all that common, but places that have wind, water, and places where underground chambers can be built are much more available. This sounds really promising

According to Spector, “The Terra solution is highly customizable and allows customers to pick the power-to-energy ratio. For systems of 200 megawatts or more, VanWalleghem said, Hydrostor can deliver 6 to 8 hours of duration on a turnkey installed basis of $150 per kilowatt-hour.”

So $30 million gets a peaker plant that can store night generated wind in Texas, where capacity is such that sometimes operators have to pay the grid to haul excess power away, and it can be turned into $0.20/kwh peak electricity. Recover cost in 3,000 hours, if there are a hundred days of six hour peak heat in summers, that’s five years, and lifetimes on utility scale systems are measured in decades.

A 200 megawatt plant will support a western city of a hundred thousand, but it would be a much bigger deal here – Capetown, South Africa, with a population roughly five times that size.

Capetown

Capetown

Wind is a big deal in South Africa, almost no capacity in 2012, two gigawatts now, and another three gigawatts coming. I’m not sure what fifty five million there need in terms of power, life is very different than California. Our 2kw/house metric is much higher than their requirements, perhaps by a factor of ten.

Hydrostor’s work thus far has been with fresh water. When they do their first saltwater system I’ll get really interested. If there is a deep cavern into which salt water enters, that means there is natural pressure – which can be used for osmotic desalination or maybe a graphene system. South Africa could really use more fresh water.

South African Climate

South African Climate

 

Hopefully we’ve managed to avoid War With North Korea, at least for this weekend, but I’m still thinking about Functional Triage. I like South Africa’s industrialization and their isolation from the problems in the northern hemisphere. They need to focus on renewable investments, but with the added calculus that things up north might go irreparably sideways, as we came so near to doing this weekend.

 

Promise Of Perovskite

Perovskite solar cells were a novelty in 2009, 3.5% efficient for a few minutes before they decayed. Eight years later they are 22% efficient and while the only Amazon results for ‘Perovskite’ are chemistry text books, reports indicate cells based on this technology may become commercially available this year.

The Wiki is a bit dizzying for a non-chemist. The solar cells we know today are semiconductor products, like large computer chips. They require precise manufacturing techniques at high temperatures and pressures, similar to chip foundry techniques. Perovskite cells are created with organic solutions that are much easier to handle, in some cases apparently being created with ink jet printing techniques.

Solar Cell Farm

Solar Cell Farm

Olduvai Theory is the idea that an industrial civilization in this biosphere is a single pulse transient; we get a century of 24×7 light, heating, and cooling, then we start sliding back towards an 18th century lifestyle … if we’re lucky. Given that electricity is a matter of alnico magnets, copper wire, and something that spins, we’ve been able to generate electricity at varying scales since the 1930s. I’m not sure I agree with the rapidity of decline the theory proposes.

 

South Africa’s load shedding is a model for what a developed nation under stress might do. When you need 24 gigawatts but can only deliver 20, large areas go dark for two hour windows. Imagine how different things would be if domestically produced solar cells lined every roof. There might be blackouts in the evening, but daytime activity would remain more or less normal. That’s not what we have in 21st century America, but I think it’s much nicer than America in the 1700s. Hospitals, libraries, food storage facilities and other community resources could likely maintain 24×7 service by policy, or by owning generators. Call these ubiquitous solar cells distributed generation.

Humans are more active during daylight hours, and we’d do better health wise if we got away from our 24×7 lifestyle and bluish fluorescent lights after sundown. Solar matches both this need and the curve for when we need cooling the most. Call this timely generation.

Hydroelectric power obviously requires water, but so does utility scale generation using coal, oil, or natural gas. The largest generator I’ve ever seen that relied on a radiator was in the two megawatt range and the operator told me that chillers were required for anything much bigger. Solar cell plants may produce heat islands, but they require no cooling. Call this dry generation.

 

Any place that has distributed, timely, dry generation is much better equipped for a rapidly warming world. Let’s add an additional requirement – local manufacturing. When a new operating system is being created it is an important milestone when it becomes ‘self hosting’ – which means that the current generation was built entirely using the prior generation.

Silicon photovoltaics are like making computer chips – the province of the U.S., Europe, and the big three economies in Asia. South Africa has chip manufacturing but it’s dependent on outsiders. If they could master perovskite solar cell manufacturing that would be a huge step towards energy independence.

I don’t find a lot of good news. The potential of this dramatically cheaper dry generation method actually has me a little bit hopeful.

Mideast & Central Asian Electrical Grids

Mideast Electrical Grid

Central Asia Electrical Grid

You can’t grow wheat without water. You can’t have irrigation water without electricity. Close to the field this depends on having fuel, usually diesel, available for irrigation pumps. Closer to the source the volumes are much higher and pumps need grid connections. Keep in mind that, except for wind and solar, there is no electricity without water.

There are three types of electricity that flow over a grid.

The first is known as baseload. This is always on and built to handle the average need of the moment, with a bit of headroom to spare. Coal, hydroelectric, nuclear, and in some places gas or oil serve in this role. All except hydroelectric depend on water for cooling, while hydropower directly depends on water.

The second type are known as dispatchable or spinning reserves. Nuclear plants take days to change output and coal plants have significant thermal inertia, too – those would be spinning reserves. Hydroelectric can be dialed up or down on short notice. Large grid requirements in the U.S. are handled with ‘peaker’ natural gas turbines. Rural areas like where I grew up do it differently – each town has a small generating plant and they get called into service during peak usage.

The third type are intermittent. Wind blows where and when it wants, solar is diurnal, and smaller hydroelectric plants can be intermittent. New England is dotted with small dams and pump houses that provide some of the local need, but they aren’t always available the way Niagara Falls power is.

Solar and wind are the only power sources we have that don’t need large amounts of water. Solar is the best first investment for the dry, sunny Mideast countries. The production curve matches peak utilization, generation happens near consumption, and the infrastructure needed is much smaller than the investment for wind.

What will happen when drought leads to the shutdown of a major generating plant? What happens if the grid suffers an attack? A single carefully selected transmission line pylon going down can cause havoc during peak load.

Things are different in the Mideast than they are in western countries. Some areas have never experienced the stable electrical grid we take for granted in the U.S. Load shedding, or rolling blackouts, are a feature of life. Irrigation still works when power is intermittent, but this puts a tremendous drag on the overall economy.

I found a number of country grid maps, too. Sadly, resolutions are poor, they are often in Arabic, and there are some places that are simply not covered. I was hoping to be able to draw some conclusions about the effects of drought on food production, with water and electricity as the variables. More digging will be required before I an do that.