ESS Tech : First Quarter 2024 Earnings Announcement Presentation

Long-Duration

Energy Storage Systems for a Cleaner Future

May 2024

Disclaimers

This presentation includes forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended (the "Securities Act") and Section 21E of the Securities Exchange Act of 1934, as amended (the "Exchange Act"). These forward-looking statements can be identified by the use of forward looking terminology, including the words "believes," "estimates," "anticipates," "expects," "intends," "plans," "possible," "may," "might," "will," "potential," "projects," "predicts," "continue," "could," "would" or "should," or, in each case, their negative or other variations or comparable terminology. These words and similar expressions may identify forward-looking statements, but the absence of these words does not mean that a statement is not forward-looking. These forward-looking statements, which are subject to risks, uncertainties and assumptions about us, may include projections of our future financial performance, our anticipated growth strategies and anticipated trends in our business. These statements are based on management's current expectations, but actual results may differ materially due to various factors, risks, and uncertainties, including, but not limited to: our financial and business performance, including financial projections and business metrics; changes in our strategy, future operations, financial position, estimated revenues and losses, projected costs, prospects and plans; the implementation, market acceptance and success of our technology implementation and business model; our ability to scale in a cost-effective manner; developments and projections relating to our competitors and industry; our expectations regarding our ability to obtain and maintain intellectual property protection and not infringe on the rights of others; our future capital requirements and sources and uses of cash; our ability to obtain funding for our operations; our business, expansion plans and opportunities; our relationships with third-parties, including our suppliers, customers, and partners; issues related to the shipment and installation of our products; issues related to customer acceptance of our products; the outcome of any known and unknown litigation and regulatory proceedings; and other risks and uncertainties discussed elsewhere in our public filings. The forward-looking statements contained in this report are based on our current expectations and beliefs concerning future developments and their potential effects on us. There can be no assurance that future developments affecting us will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond our control) and other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. Should one or more of these risks or uncertainties materialize, or should any of our assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements. We undertake no obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise, except as may be required under applicable securities laws. These risks may not be exhaustive. By their nature, forward-looking statements involve risks and uncertainties because they relate to events and depend on circumstances that may or may not occur in the future. We caution you that forward-looking statements are not guarantees of future performance and that our actual results of operations, financial condition and liquidity, and developments in the industry in which we operate may differ materially from those made in or suggested by the forward-looking statements contained in this report. In addition, even if our results or operations, financial condition and liquidity, and developments in the industry in which we operate are consistent with the forward-looking statements contained in this report, those results or developments may not be indicative of results or developments in subsequent periods.

All rights to the trademarks, copyrights, logos and other intellectual property listed herein belong to their respective owners and ESS's use thereof does not imply an affiliation with, or endorsement by the owners of such trademarks, copyrights, logos and other intellectual property. Solely for convenience, trademarks and trade names referred to in this Presentation may appear with the ® or symbols, but such references are not intended to indicate, in any way, that such names and logos are trademarks or registered trademarks of ESS.

Any financial and operating forecasts and projections contained herein represent certain estimates of ESS as of the date thereof. ESS's independent public accountants have not examined, reviewed or compiled the forecasts or projections and, accordingly, neither expresses an opinion or other form of assurance with respect thereto. ESS and its management team cannot give any assurance that the forecasts or projections contained herein accurately represent ESS's future operations or financial conditions. Such information is subject to a wide variety of significant business, economic and competitive risks and uncertainties, including but not limited to those set forth above that could cause actual results to differ materially from those contained in the prospective financial information. Accordingly, there can be no assurance that the prospective results are indicative of the future performance of ESS or that actual results will not differ materially from those presented in the prospective financial information. Some of the assumptions upon which the projections are based inevitably will not materialize and unanticipated events may occur that could affect results. Therefore, actual results achieved during the periods covered by the projections may vary and may vary materially from the projected results. Inclusion of the prospective financial information in this presentation should not be regarded as a representation by any person that the results contained in the prospective financial information are indicative of future results or will be achieved.

This Presentation contains statistical data, estimates and forecasts that are based on independent industry publications or other publicly available information. This information involves many assumptions and limitations and you are cautioned not to give undue weight to these estimates. We have not independently verified the accuracy or completeness of the data that has been contained in these industry publications and other publicly available information. Accordingly, neither ESS nor its respective affiliates and advisors makes any representations as to the accuracy or completeness of these data. This Presentation contains references to ESS's achievements compared to other companies. All of such references are based on the belief of ESS's management based on publicly available information known to ESS's management.

The financial information and data contained in this Presentation is unaudited and does not conform to Regulation S-X promulgated under the Securities Act of 1933, as amended. This Presentation also includes non-GAAP financial measures, including gross margin, non-GAAP operating expenses and Adjusted EBITDA. ESS believes that these non-GAAP measures of financial results provide useful information to management and investors regarding certain financial and business trends relating to ESS's financial condition and results of operations. ESS's management uses certain of these non-GAAP measures to compare ESS's performance to that of prior periods for trend analyses and for budgeting and planning purposes. Not all of the information necessary for a quantitative reconciliation of these forward-lookingnon-GAAP financial measures to the most directly comparable GAAP financial measures is available without unreasonable efforts at this time. Specifically, ESS does not provide such quantitative reconciliation due to the inherent difficulty in forecasting and quantifying amounts necessary for such reconciliations.

Catalyzing a Clean Future. Every Day.

1

ESS Technology	is Commercially Available Today
Large and	Simple, yet
fast-growing TAM	revolutionary technology
Compelling	Low risk
value proposition	expansion plan

Considerable pipeline of opportunities

Catalyzing a Clean Future. Every Day.

2

Resiliency

and reliability are harder with intermittent resources.

Catalyzing a Clean Future. Every Day.

3

Renewable Penetration Drives Energy Storage Needs

Sharper and

sharper ramps turn the duck curve into a canyon curve

Overgeneration and curtailment result

KW

600

400

200

0

Storing energy

Releasing

stored energy

Releasing stored energy

Load

Solar Energy

6AM	12PM	6PM	12AM
		Time of Day

Energy shift to evenings using long-duration storage

Lack of storage caused more than 2.6 TWh to be wasted in 2023 in California alone

Catalyzing a Clean Future. Every Day.

Source: EIA, CAISO and Company reports

4

$3 Trillion Investment

Catalyzing a Clean Future. Every Day.

	TWh Cumulative installed energy capacity	USD bn Cumulative
	capex investment
2040									~85		-140		TWh		~$1500-3000B
2035			~35-	70 TWh											~$1100-1800B
2030		~5	-10 TWh												~$200-500B
2025		~1 TWh														~$50B
0	20	40	60	80	100	120	140

1 TWh = 1 million MWhs

More information www.ldescouncil.com	5

Batteries are a BIG Part of the Solution

1800

1600

1400

											Oil
($B)	1200													Fuel Cells
													Electrolyzers
Size	1000													Offshore Wind
								Onshore Wind
													Solar PV
Market	800
	600
	400
									Batteries
	200
	0
	2020	2030	2040	2050

Catalyzing a Clean Future. Every Day.

Source: IEA, World Energy Outlook, 2021

6

Li-ion Presents Roadblocks to Energy Transition

Short-term	Critical
energy capacity	mineral mining

ExpensiveEnergy

long-termsecurity

Catalyzing a Clean Future. Every Day.

7

Global Collaboration to Advance Iron Flow Battery Market Adoption

Go-To-Market	Intellectual Property
Honeywell to integrate	ESS license to Honeywell's flow
ESS technology into	battery intellectual property
global go-to-market offering
$300M targeted purchases	Joint Innovation
in first phase of agreement	Companies invest in joint
	development for continual technology
Global reach to	advancement, cost reduction and
Honeywell's customers	packaging of IFB systems

Catalyzing a Clean Future. Every Day.

"The demand for long-duration energy storage represents a compelling market opportunity within the energy transition and the combination of Honeywell and ESS technology can accelerate decarbonization for the commercial, industrial and utility sectors."

Bryan Glover

Chief Growth Officer

Honeywell Performance Materials and Technology (PMT) group

8

Representative ESS Deployments

Airside Operations

Distributed Generation

Utility-Scale DER	Utility-Scale DER

Green Baseload Energy

Catalyzing a Clean Future. Every Day.

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