As so­lar floods Cal­i­for­nia grid, chal­lenges loom

To fill the gaps when so­lar isn’t avail­able, the state re­lies on plants that burn nat­u­ral gas

The Hamilton Spectator - - BUSINESS - DAVID R. BAKER

The same clear, sunny weather that broiled much of Cal­i­for­nia in near-triple-digit heat this past week also helped the state’s so­lar power plants set a record, briefly gen­er­at­ing enough elec­tric­ity for more than six mil­lion homes.

Just af­ter 1 p.m. Tues­day, large so­lar plants scat­tered across Cal­i­for­nia pro­duced a record 8,030 megawatts of elec­tric­ity, ac­cord­ing to the Cal­i­for­nia In­de­pen­dent Sys­tem Operator, the or­ga­ni­za­tion that op­er­ates most of the state’s re­new­ables grid. That’s nearly twice as much so­lar power as Cal­i­for­nia could gen­er­ate just two years ago.

But the push to add re­new­able power has other com­pli­ca­tions, given that the sun doesn’t shine at night and wind is in­ter­mit­tent, too.

The out­put from so­lar plants peaks at mid­day, stays close to that level for sev­eral hours and then tails off sharply in late af­ter­noon. Cal­i­for­nia’s wind farms pro­duce most of their elec­tric­ity from late af­ter­noon into the night. Elec­tric­ity de­mand, mean­while, tends to hit its daily peak around 6 p.m. — just as so­lar power is fad­ing and wind is still revving up.

To fill the gap, the state re­lies on power plants that burn nat­u­ral gas, plants that can ramp their out­put up and down quickly. Util­i­ties such as Pa­cific Gas & Elec­tric Co. also of­fer cus­tomers in­cen­tives to use less power, through mea­sures such as turn­ing off lights, dur­ing the crit­i­cal af­ter­noon hours. On Fri­day, for ex­am­ple, PG&E asked some cus­tomers to power down be­tween 2 and 7 p.m.

“We’re chang­ing our par­a­digm from a grid that is largely tra­di­tional re­sources aug­mented by re­new­ables to one that’s based on re­new­ables aug­mented by tra­di­tional re­sources, mostly nat­u­ral gas,” said Steve Berberich, CEO of the In­de­pen­dent Sys­tem Operator. “Our goal is to make the gas el­e­ment as small as pos­si­ble.”

When elec­tric­ity de­mand on Tues­day reached its peak al­most 29 per cent of the elec­tric­ity cours­ing over the grid came from re­new­able sources, ac­cord­ing to the In­de­pen­dent Sys­tem Operator.

For a brief time on May 16, re­new­ables ac­counted for 56 per cent of the grid’s elec­tric­ity, ac­cord­ing to the operator.

These fig­ures don’t count the elec­tric­ity gen­er­ated by the more than 537,000 rooftop so­lar ar­rays on houses and busi­nesses. To­gether, those ar­rays can pro­duce up to 4,211 megawatts of elec­tric­ity.

PG&E, which is Cal­i­for­nia’s largest util­ity, es­ti­mates that Cal­i­for­nia’s in­creas­ing use of so­lar and wind en­ergy pushes up elec­tric­ity rates be­tween one and two per cent each year. Re­new­able power prices, how­ever, are drop­ping fast, as more so­lar and wind projects come on­line.

The grow­ing avail­abil­ity and de­clin­ing price of re­new­able power con­trib­uted to PG&E’s de­ci­sion to close Cal­i­for­nia’s last nu­clear plant, Di­ablo Canyon, in 2025. PG&E has pledged to re­place the plant with elec­tric­ity sources that don’t pump green­house gases into the at­mos­phere, so that the util­ity would get 55 per cent of its elec­tric­ity from re­new­able sources.

“Each time we go out for bids, re­new­able prices have been go­ing down, par­tic­u­larly pho­to­voltaic (so­lar), and we have no rea­son to be­lieve that’s not go­ing to con­tinue,” Ear­ley said.

One chal­lenge, para­dox­i­cally, is that Cal­i­for­nia has added so many so­lar plants that the grid doesn’t al­ways have room for all of the elec­tric­ity.

On Tues­day, for ex­am­ple, grid op­er­a­tors had to cur­tail 292 megawatt-hours of so­lar elec­tric­ity, equal to 292 megawatts over the course of an hour.

To deal with oc­ca­sional ex­cess power, the In­de­pen­dent Sys­tem Operator is ex­plor­ing the pos­si­bil­ity of launch­ing a uni­fied power mar­ket that would cover most western states, so that Cal­i­for­nia’s so­lar plants and wind farms could sell their ex­cess power to cus­tomers out­side the state.

Our goal is to make the gas el­e­ment as small as pos­si­ble.” STEVE BERBERICH, IN­DE­PEN­DENT SYS­TEM OPERATOR

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