Thread by @nworbmot

Can we meet baseload electricity demand from wind, solar and storage alone?

Thread summary: Yes. Today it's a bit expensive, in a decade it will be reasonable. Costs even lower if we use other low-carbon sources too (existing hydro, sustainable biomass, nuclear, CCS, etc.)

In this thread we demonstrate this claim with an open model that anyone can download and play with, see http://github/PyPSA/WHOBS. It's based on the free software modelling framework github.com/PyPSA/PyPSA and open weather data from renewables.ninja. @openmod

We concentrate on European countries. We optimise over 31 years of hourly historical data to get a wide selection of weather events. We only allow onshore wind, utility-scale solar PV, batteries and hydrogen (H2) storage. They have to meet a flat demand profile (i.e. baseload)

Obviously if they can meet a flat demand profile, they can meet any profile, since all the technologies involved are flexible.

Electrolysis of hydrogen is critical to bridge multi-day events with low wind and solar. Hydrogen can be stored underground just like we do today for natural gas (Europe has around 1070 TWh of gas storage agsi.gie.eu; electricity demand is just over 3000 TWh per year)

This is a dumb setup for (at least) 3 reasons: i) extra tech would lower cost to get to zero CO2, e.g. using other low-CO2 sources (see list in 1st tweet), including transmission connections and demand-side management. But we can put an upper bound on cost of low-CO2 systems

ii) 80% wind+solar is possible without storage and without high costs, so this is a discussion about the "last mile" we have to travel in 2030 and beyond. iii) integrating heat and transport (ignored here) would offer additional flexibility (think BEV DSM and thermal storage).

Using today's costs (2020), 5% cost of capital (higher than WACC in mature markets like Germany) and underground H2 storage (e.g. in salt caverns
or depleted oil and gas fields) (see github.com/PyPSA/WHOBS/bl… for all assumptions) in most countries the cost is over 100 EUR/MWh

This is higher than today's electricity production costs (around 50-70 EUR/MWh in Europe), but the setup is *very* restricted. For example, Norway, Switzerland and Austria have plenty of flexible hydro they could be using instead.

By 2030 we assume costs reduce and a lower cost of capital (3%) due to investors becoming comfortable with the technology. Costs are now within shooting distance of today, even without hydro, biomass, nuclear, CCS, cross-border exchange, other storage, DSM, sector coupling

In many places this is within the 30% bill increase that might be tolerated by consumers for 100% renewable electricity written up recently by @drvox

vox.com/energy-and-env…

Finally for 2050 assumptions (very uncertain) we're within range of today's costs, but without all the health and climate costs. Studies that include other techs (and other energy sectors) reach lower costs by reducing the need for electricity storage (e.g. with flexible hydro)

Why are these costs more than the levelised cost of energy (LCOE) for wind and solar? Because LCOE doesn't take account of when the power is generated; if we require power at every hour, we need storage and it's cost-effective to curtail some wind and solar; both push up costs

What about market value? It's a long-term equilibrium without additional constraints, so the absolute MV is the same as the marginal cost for each technology. Relative to the average market price, for Germany this is 52% for solar, 67% for wind.

The flexibility required to balance wind and solar supports the market values. The market value for electrolysers are 33% and 181% for H2 turbine; for battery charging 45% and discharging 142%. "Buy it cheap, sell it expensive."

Wind and solar dominate the total system costs, and since all assets make back their costs from the market price, their cost recovery also dominates the market price. Therefore their market values cannot sink too low in a long-term equilibrium.

Do these results contradict a recent MIT study doi.org/10.1016/j.joul… by @nsepulvedam, @JesseJenkins et al showing wind+solar+storage is expensive without other low-carbon sources? No, they're complementary: the type of model is the same, we just included long-term H2 storage

Our model requires a month or more of H2 storage in most countries. With other techs this would reduce. Europe already has large natural gas storage facilities, equal in energy capacity to one third of it's yearly electricity demand

Hydrogen can be stored in depleted gas and oil fields, salt caverns, mines and porous rocks. Here are some costs from NREL nrel.gov/docs/fy10osti/… . This is already done at large scale at several facilities, see e.g.

en.wikipedia.org/wiki/Undergrou…

hub.globalccsinstitute.com/publications/o…

(Salt caverns are of course restricted to where there are salt deposits, but these are widely spread around Europe and the US)

There are real examples of renewables+hydrogen systems up to 20 years old, but mostly niche applications like islands or off-grid demonstrations

doi.org/10.1016/j.sole…

globalislands.net/greenislands/d…

new.abb.com/news/detail/64…

horizon-magazine.eu/article/hydrog…

linkedin.com/pulse/true-pio…

Don't like H2 storage? You can also do long-term storage with methane for similar costs. Power-to-methane can reach 75-85% efficiency if you're clever

helmeth.eu/index.php/proj…

and you have a CO2 source. Then use existing natural gas for storage and transportation.

You can convert back to power with e.g. a CCGT or Allam turbine and capture the CO2 for the methanation. Voila! Methanation is maybe twice as expensive as electrolysis alone, but storage can use existing natural gas infrastructure.

Electricity storage is unlikely to be the main application of power-to-gas (P2G) in low-carbon systems; P2G may also be needed to meet heat demand peaks, difficult-to-electrify transport sectors, process heat and for industrial chemical production (for future theads)

A final plea: If anyone has web skills, we can build a site like renewables.ninja, where you can click on any point in the world and get an optimised wind+solar+storage system for the local weather conditions. Just drop me a DM/email.

Link to data and code is:

github.com/PyPSA/WHOBS

All model output (dispatch time series etc.) for all 120 runs (30 countries x 4 scenarios) now on Zenodo for posterity (6.6 GB). If you just want the results summaries (capacities of tech, etc), they're in the github repository github.com/PyPSA/WHOBS/tr…

doi.org/10.5281/zenodo…

Scientifically, there's nothing novel about this toy model, except perhaps the large number of years (31) in the optimisation. In our more regular work, we include more realistic loads, electricity grid, more technologies and more energy sectors, see e.g.

nworbmot.org/publications.h…