PHOTO - Walt Disney World's solar facility goes live

LensmanMay 09, 2019

After net metering expired, the next grid supply program credited customers $0.15 per kWh. That program filled up (50 MW) and the next program only credited customers $0.10 per kWh and is still open (35 MW capacity). There's also an additional program that only allows grid export from 4pm to 9am but credits you $0.15 per kWh (25 MW capacity). Something I just remember that you'd be interested in is that most islands' grids are seeing curtailment at some point during the year, so you're right and Hawaii has reached the point where they have to only build out dispatchable solar+storage. It was in the news that their latest (utility-scale) solar+storage PPAs came in at less than $0.10 per kWh. Last I checked retail electricity was about $0.33 per kWh.

GoofGoofMay 09, 2019

Those credits are a drop in the bucket compared to the tax benefits fossil fuel energy companies receive. The credits do phase out so you will get your wish, but it really hasn’t slowed things much.

GoofGoofMay 09, 2019

I know they did away with net metering a few years back for any new installations. Lack of net metering with the grid strongly encourages battery backup. If you can’t sell excess MWHs back to the grid at retail prices then it makes it more economic to store that power and use your own power at night instead of drawing from the grid. My guess is that’s what is going on there. It’s encouraging to see people are still adding solar despite losing net metering. Could be a model for the rest of the country to follow. Hawaii is unique because it’s an island so no gas pipelines or railroads so you can’t easily get coal or nat gas delivered, at least not economically.

LensmanMay 09, 2019

Regarding Hawaii, here's a one-day graph of demand and PV production on Oahu: 1. Net system load - this is the actual electrical demand at the meter. Note: The x-axis for this is 500 MW, not zero. 2. Gross system load - this adds back in an estimate for behind-the-meter solar. Note: The x-axis for this is 500 MW, not zero. 3. Utility-scale PV generation - this includes all utility scale PV generation. Note: The x-axis for this is 0 MW So for example, at 11 am, utility scale PV is generating about 160 MW and demand is 610 MW. Note: I hate this graph, it's terrible! Pretty much all the new PV projects they have planned include some amount of storage (generally 4x the nameplate MW in MWh of storage). I'm not sure whether this is because they've reached the amount of pure PV that they've calculated that they need or whether they've decided to address their early evening peak first. I do know that in the summer, you get >6 MWh generation per MW, so those PV+storage facilities will be dumping some power onto the grid during the day. Also note that they have a 90 MW waste-to-energy plant that they have to keep running (and using the power from). Here's a link to the Hawaiian Electric daily renewables watch: https://www.hawaiianelectric.com/clean-energy-hawaii/integration-tools-and-resources/renewable-watch

jt04May 09, 2019

I support sun setting the tax credits until more is understood about renewables and energy storage costs etc.

GoofGoofMay 09, 2019

IMHO they have some more to go. There comes a point where without better battery storage you max out on the amount of effective renewables for a grid. Florida is nowhere near that point. Hawaii probably is. CA might get close pretty soon. Remember this, TWDC is not a charity and they don’t like to incur excess costs. If solar prices continue to drop they will be moving that direction for pure economics without even considering the environmental impact. If you don’t believe that look at the Texas market today. ERCOT (the grid manager for most of Texas) released a report showing 5,000 MWs of new renewables (mostly solar) planned to come online in the next 3 years. The Texas market is completely de-regulated so those plants are being built based on economics alone. There is a federal investment tax credit but that starts phasing out after 2019. The point is there isn’t a state mandated renewable portfolio standard driving this growth, it’s just that these projects are cheaper and easier to build than fossil plants. Here’s the ERCOT press release. http://www.ercot.com/news/releases/show/181248

GoofGoofMay 09, 2019

As @Lensman said, a lot of the new construction natural gas plants are combined cycle using a gas turbine and then using the exhaust heat to boil water for use in a 2nd steam turbine. These plants are the ones typically replacing older coal plants and run almost continuously. In the case where a company is converting a coal or oil burning plant to natural gas they are usually simple cycle steam turbines. Basically you just replace the heat source and it’s a relatively cheap conversion. Gas turbines alone are mostly just used for peaking plants that ramp up and down fast and often. Back in the day they used jet engines running on kerosene or in some cases natural gas as peakers. I don’t have a breakdown on types, but I would guess the overall capacity of natural gas steam turbines probably exceeds combined cycle, but combined cycle probably produces more MWHs in a year due to the continuous run time.

jt04May 08, 2019

Just to clarify, it seems to me WDW has installed an ideal amount of solar. Enough to help offset peak demand for air conditioning but not so much as to stress the 'grid' during several days of consecutive overcast skies.

LensmanMay 08, 2019

There are two kinds: 1. The combustion turbines that you mention. Power plants using this technology are commonly called "gas peakers" in the industry because they are typically used on an on-demand basis during peak demand periods of the day. They run at about 35% thermal efficiency. 2. Newer combined cycle gas turbine plants have a conventional gas turbine that generates electricity, but then uses the waste heat from the exhaust to boil water in a secondary steam generator. It's really two power plants in one. Overall, the thermal efficiency of these can be as high as 62%. The downside of the combined cycle plant is that it is inefficient to run it for dispatchable power, as it takes time for the secondary steam generator to "get up to speed" and be effective at producing electricity. However, in this mode it is no less efficient than a gas peaker. However, running it in this mode means that the expensive steam generator that you built mostly goes to waste, so most combined-cycle plants are run to provide baseload power.

LensmanMay 08, 2019

In some sense, it doesn't matter what you, @GoofGoof, or I believe. The U.S. Department of Energy projects that 24 GW of (utility scale) electrical generating capacity will come online 2019: 46% wind (10.9 GW) 34% natural gas (6.1 GW combined cycle and 1.4 GW combustion turbine) 18% solar (4.3 GW) In addition, they project 3.9 GW of behind-the-meter distributed generation solar. But like you said, we'll just have to see how things pan out. I had high hopes for V.C. Summer units 2 and 3 (1.1 GW each), but it's abandonment after SCE&G spent over $5 billion deflated my enthusiasm. Estimates to finish the project seemed to range between $16 billion and $25 billion. That's $7,000 and $11,000 per kW. Even with the high utilization factor of nuclear, that's uneconomic. I might be willing to pay it as a ratepayer, but I wouldn't begrudge anyone else from shying away, especially since you're talking about what's supposed to be cheap baseload power.

DisneyCaneMay 08, 2019

I always assumed that natural gas power plants were gas turbines. Are modern natural gas plants really stream turbines with gas used to boil water? Is that more efficient?

GoofGoofMay 08, 2019

Some more info from EIA Electricity, coal, renewables, and emissions EIA expects the share of U.S. total utility-scale electricity generation from natural gas-fired power plants to rise from 35% in 2018 to 37% in 2019 and to 38% in 2020. EIA forecasts that the share of electricity generation from coal will average 24% in 2019 and 22% in 2020, down from 27% in 2018. The nuclear share of generation was 19% in 2018, and EIA forecasts that it will stay near that level in 2019 and in 2020. The generation share of hydropower averages 7% of total generation in EIA’s forecast for 2019 and 2020, similar to 2018. Wind, solar, and other nonhydropower renewables together provided about 10% of electricity generation in 2018. EIA expects they will provide 11% in 2019 and 13% in 2020. EIA forecasts that all renewable fuels, including wind, solar, and hydropower, will produce 18% of U.S. electricity in 2019 and almost 20% in 2020. EIA expects that wind generation will surpass hydropower generation for the first time to become the leading source of renewable electricity generation in 2019 and maintain that position in 2020. EIA estimates that U.S. coal production in the first quarter of 2019 was 170 million short tons (MMst), 22 MMst (12%) lower than the previous quarter and 17 MMst (9%) lower than production in the first quarter of 2018. EIA expects that coal production will fall during the forecast period as demand for coal (domestic consumption and exports) declines. EIA forecasts that coal production will total 700 MMst in 2019 and 638 MMst in 2020 (declining by 7% and 9%, respectively).

GoofGoofMay 08, 2019

Hydro was 7% of it, wind and solar 10% and about 2% from biomass and other. That’s utility scale power. Small-scale solar projects less than 1 MW (home solar) was about 1% of the total.

jt04May 08, 2019

How much of that 20% was not wind and solar?