If Germany is to meet its ambitious goals of getting a third of its electricity from renewable energy by 2020 and 80 percent by 2050, it must find a way to store huge quantities of electricity in order to make up for the intermittency of renewable energy.
Siemens says it has just the technology: electrolyzer plants, each the size of a large warehouse, that split water to make hydrogen gas. The hydrogen could be used when the wind isn't blowing to generate electricity in gas-fired power plants, or it could be used to fuel cars.
Producing hydrogen is an inefficient way to store energy—about two-thirds of the power is lost in the processes of making the hydrogen and using the hydrogen to generate electricity. But Siemens says it's the only storage option that can achieve the scale that's going to be needed in Germany.
Unlike conventional industrial electrolyzers, which need a fairly steady supply of power to efficiently split water, Siemens's new design is flexible enough to run on intermittent power from wind turbines. It's based on proton-exchange membrane technology similar to that used in fuel cells for cars, which can operate at widely different power levels. The electrolyzers can also temporarily operate at two to three times their rated power levels, which could be useful for accommodating surges in power on windy days.
prajeshbhat wrote:Especially when it leads to the loss of 66% of the power.
The thermodynamic limits assume that the engine is operating under ideal conditions: a frictionless world, ideal gases, perfect insulators, and operation for infinite time. Real world applications introduce complexities that reduce efficiency. For example, a real engine runs best at a specific load, termed its power band. The engine in a car cruising on a highway is usually operating significantly below its ideal load, because it is designed for the higher loads required for rapid acceleration. In addition, factors such as wind resistance reduce overall system efficiency. Engine fuel economy is usually measured in the units of miles per gallon (or fuel consumption in liters per 100 kilometers) for automobiles. The volume of hydrocarbon assumes a standard energy content.
Most steel engines have a thermodynamic limit of 37%. Even when aided with turbochargers and stock efficiency aids, most engines retain an average efficiency of about 18%-20%.[8] Rocket engine efficiencies are better still, up to 70%, because they operate at very high temperatures and pressures and can have very high expansion ratios.[9]
http://en.wikipedia.org/wiki/Internal_combustion_engine#Energy_efficiency
prajeshbhat wrote:Much better to grow up and learn to live with less luxury.
Building warehouse sized electrolyzers is not worth the effort.
Especially when it leads to the loss of 66% of the power.
SeaGypsy wrote:Under the same philosophy we would never have had motorized transport, given roughly the same percentage is lost as heat in combustion engines.Same goes for most electric plants.
cephalotus wrote:I don't want to live without electricity. Better to have expensive electricity than no electricity at all.
prajeshbhat wrote: This electricity is already 3 times more expensive than conventional electricity. Losses during storage will make it even more expensive.
prajeshbhat wrote:
The thermodynamic losses in motor vehicles and thermal power plants were tolerable, given that the energy was derived by simple burning dirt cheap fossil fuels. But in this article, they are talking about storing energy derived from electricity which is derived from renewable energy sources. This electricity is already 3 times more expensive than conventional electricity. Losses during storage will make it even more expensive.
Not a problem as long as you are willing to pay more per unit of electricity. If you can afford it, go for it.
cephalotus wrote:prajeshbhat wrote:
The thermodynamic losses in motor vehicles and thermal power plants were tolerable, given that the energy was derived by simple burning dirt cheap fossil fuels. But in this article, they are talking about storing energy derived from electricity which is derived from renewable energy sources. This electricity is already 3 times more expensive than conventional electricity. Losses during storage will make it even more expensive.
We are not talking about average prices, but about "the last 10% in long term storage" (in a world of 100% reneable energies, In Germany mostly wind + PV). Wind energy in Germany (onshore) costs between 5-8 €ct/kWh, but on some days wind power plants are already shut down here. So we are talking about thrwoing away that electricity for nothing.
If the hydrogen will cost 15 €ct/kWh and the electricity from burning hydrogen will cost 50 €ct/kwh than this will be perfectly ok for "the last 10%".
Make mix of 70% wind energy at 8 €ct/kWh, 20% PV at 10 €ct/kWh, 10% water+biomass at 15 €ct/kWh in coming years and 30% at +5ct/kWh for short term storage together with 10% of hydrogen (or methane) long term storage (10% are losses in the short term storga systems) you end with an average price of ca. 15 €ct/kWh.
This is more expensive than today (average prices are around 6 €ct/kWh), but at only 3%/a inflation 6 ct today will be 15ct in 30 years anyway.Not a problem as long as you are willing to pay more per unit of electricity. If you can afford it, go for it.
I now pay 25 €ct/kWh for "100% green electricity" and if I have to pay 50 €ct/kwh I will do so. Doesn't really matter to me, I have very efficient equippment. Even driving an electric car would be ok at such prices compared to our prices for gas.
I see this as a much more realstic (and desirebale) scenario compared to scenarios with no electricity and no gas at all or comapred to energy scenarios that involve destroying our ecosystems.
ymmv
dsula wrote:Having a tiny 80M people or so nation turn "green" is not that hard, as long as you can export a large chunk of your carbon consumption to 3rd world producers.
The boxes in Germany's stores frequently read "made in china".
dsula wrote:The actual question is if renewable can sustain itself, very doubtful,
Having a tiny 80M people or so nation turn "green" is not that hard,
as long as you can export a large chunk of your carbon consumption to 3rd world producers.
The boxes in Germany's stores frequently read "made in china".
Hydrogen Fuel Cell
What about electrolysis of water into hydrogen for later use either in fuel cells or combustion engines? I’ll ignore the combustion option, as the heat engine efficiency would be abysmal compared to the other storage options on the table. Batteries, gravitational storage, and flywheels can achieve better than 80% round-trip efficiency. Compressed air is harder for me to evaluate, lacking adequate knowledge on compression/extraction devices built for efficiency.
Electrolysis for the production of hydrogen tends to range between 50–70% efficient. Then the fuel cell converts the stored energy back into electricity at 40–60% efficiency for a round-trip efficiency of 20–40%. If you happen to want some of the waste heat, then you might boost the efficiency estimate (true for any of these storage methods, actually). But in a straight-up apples-to-apples comparison, the hydrogen method is a very lossy storage option. If it were dirt cheap and low-tech, I might be more excited about its potential, despite the poor efficiency. But since the opposite is true, I’m not revved up over hydrogen storage.
I spent some time searching for a hydrogen fuel cell that I could buy today with a rating in the 10 kW range (appropriate for a home). I saw some production models achieving efficiencies ranging from 40–53%, but never a price tag. If you have to submit a query to learn the price, you probably can’t afford it…
prajeshbhat wrote:Got Storage? How Hard Can it Be?...
Electrolysis for the production of hydrogen tends to range between 50–70% efficient…
People who use renewable energy(solar panels etc.) in their homes often say that the first thing you must do is to lower your energy needs by 90%.
In the future, renewable energy will probably be used keep the lights on. In India, there is a company called Selco Solar. They install 40 watt systems in poor rural Indian homes. It charges during the day and stores electricity in batteries to be used during the night. Good enough to light 2 bulbs. Costs around $150.
This is the kind of adjustment most people around the world will have to consider. Electricity from fossil fuel plants that continue to operate for a few more decades will be reserved for the elites. It is nearly impossible to run an industrial civilization as on the current scale. Big wind turbines and megawatt scale solar plants will become unaffordable soon. Most of us will have to learn to live with 40 watt systems and 2 bulbs.
cephalotus wrote:
That's peak oil porno.
We are not talking about 40W solar systems in Germany, we are talking about 25 GW that are currently installed. Maybe more than 30GW by the end of 2012. Add to this almost 30GW of wind power.
Electricity demand for Germany is between 40GW and 80GW.......
As a means of addressing its severely struggling economy, Spain eliminated subsidies to the “green” energy industry this year, The Heritage Foundation reported in February.
And now Germany is following suit.
“Germany’s parliament approved record cuts in aid for solar power, aiming to reduce the annual pace of installations by half in the world’s biggest market for the industry,” Bloomberg reports.
“Subsidies will be cut by as much as 29 percent starting April 1, depending on the size of the solar plant, according to the legislation posted on the parliament’s website.”
“The measure passed by 305 votes to 235 on the strength of Chancellor Angela Merkel’s coalition majority,” the report adds.
.....German company Solar Millennium on Wednesday filed for insolvency, putting in doubt the future of its 2,250-megawatt pipeline of power plants.......
I can’t remember where I ran across these — I think a reader shared them with me — but I started going through a bunch of old drafts of articles I wanted to write but never got to last night (Spring cleaning, I guess) and ran across them again. Basically, the image and tables below show how renewable electricity generation has changed over the years. Visit the German website I got all this from for more.
As you can see, up until the late 1990s, the only renewable energy source for electricity generation that was at all significant was hydro power.
In the middle to late 1990s, wind power started growing and had grown to a significant share of the electricity supply by the early 2000s. In 2003, it surpassed hydro power for the #1 renewable energy source for electricity, and has held that position up until today.
Biomass has also grown a lot in the 2000s, and it passed up hydro in 2007.
Solar started growing later, but you can see that its big boom in 2010 and 2011 has resulted in it becoming a major player now, as well.
Of course, the chart also shows Germany’s significant renewable energy growth (in the electricity sector) overall.
For more details, here are tables to go with the image:
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