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Exhibit 99.1 Aspen Aerogels , Inc. Reports First Quarter 2021 Financial Results and Recent Business Developments NORTHBOROUGH , Mass . , April 29 , 2021 - Aspen Aerogels , Inc. ( NYSE : ASPN ) ( " Aspen " ) today announced financial results for the first quarter of 2021 , which ended March 31 , 2021 , and discussed recent business developments . Total revenue for the first quarter was $ 28.1 million compared to $ 28.4 million in the first quarter last year . First quarter net loss was $ 6.3 million compared to a net loss of $ 3.2 million in the first quarter of 2020. Net loss per share for the first quarter was $ 0.22 compared to $ 0.13 in the first quarter last year . Adjusted EBITDA for the first quarter was $ ( 2.6 ) million compared to $ 0.5 million in the first quarter of 2020. A reconciliation of non - GAAP Adjusted EBITDA to net loss is provided in the financial schedules that are part of this press release . An explanation of this non - GAAP financial measure is also included below under the heading " Non - GAAP Financial Measures . " Q1 Business Developments " Despite the ongoing unfavorable impact of COVID - 19 in the subsea , refinery and petrochemical markets , our first quarter revenue decline was limited to 1 % due to strong demand in the global LNG market , led by shipments to the Arctic LNG and PTT LNG projects . Importantly , the pace of our e - mobility business development initiatives accelerated sharply during the quarter . Accordingly , we increased our investment in personnel , infrastructure and related activities in support of our thermal barrier and battery materials businesses during the quarter . These investments contributed to decreases in gross profit and Adjusted EBITDA and an increase in net loss versus 2020 , " stated Don Young , President and CEO of Aspen . " We are now working with more than twenty manufacturers of batteries , battery systems and electric vehicles globally . Our newly formed Advanced Thermal Barrier organization is fully engaged in providing prospective customers with PyroThinTM samples and data , designing and producing thermal barrier prototypes to customer specifications , responding to thermal barrier RFQs , developing an automated thermal barrier fabrication capability and producing thermal barriers for our major U.S. automotive customer , " continued Mr. Young , “ In addition , a growing number of battery and electric vehicle manufacturers are assessing our proprietary carbon aerogel materials for use in lithium - ion batteries of electric vehicles . We are working hard to keep pace with their demand for evaluation samples of our battery materials for testing in large - scale battery prototypes . " " We are also making good progress with our plan to construct a second manufacturing facility to expand our silica aerogel blanket capacity by the end of 2023 . During the first quarter , our dedicated team worked to determine the appropriate capacity for the second plant , to select an optimal manufacturing site and to create conceptual engineering designs for the facility , ” continued Mr. Young . 2021 Strategic Investment Program " We have decided to increase our investment levels during the remainder of 2021 to take advantage of our rapidly growing e - mobility opportunities . This planned investment includes $ 10.0 million in additional expense this year to enhance the technical , commercial and operational teams and associated resources supporting our thermal barrier and battery materials businesses . We also plan to increase capital expenditures by $ 18.0 million in 2021 to construct our Advanced Thermal Barrier Center , to expand our battery materials production , fabrication and testing facilities , and to complete the initial engineering designs for our second silica aerogel manufacturing plant , " continued Mr. Young , " We will announce additional details of this strategic investment program and associated financing arrangements as our planning efforts progress during the year . " 2021 Financial Outlook Aspen updates its 2021 full year outlook as follows : • Total revenue is expected to range between $ 103.0 million and $ 111.0 million Net loss is expected to range between $ 28.3 million and $ 31.9 million • Net loss per share is expected to range between $ 1.01 and $ 1.14 Adjusted EBITDA is expected to range between $ ( 15.2 ) million and $ ( 18.8 ) million Our 2021 outlook assumes depreciation and amortization of $ 8.9 million , stock - based compensation expense of $ 4.0 million , interest expense of $ 0.2 million , and weighted average shares outstanding of 28.0 million for the full year . A reconciliation of non - GAAP Adjusted EBITDA to net loss for the 2021 financial outlook is provided in the financial schedules that are part of this press release . An explanation of this non - GAAP financial measure is also included below under the heading " Non - GAAP Financial Measures . "