Company lists · Data refreshed September 2026

Top 25 Geothermal consultants based in the United States

RevenueBase identified 3,831 geothermal consultants headquartered in the United States as of September 2026 and tracks 75,828 professional contacts across them, including 35,143 with verified work emails. Houston is the largest hub.

This list covers geothermal consultants headquartered in the United States, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 20, 2026.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 20, 2026 86% judged on-target in blind review
3,831Companies
75,828Contacts tracked
35,143Verified emails
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The 25 largest geothermal consultants based in the United States

Ranked by team size
Top 25 of 3,831 geothermal consultants based in the United States, ranked by team size, largest first. Data refreshed Sep 20, 2026. RevenueBase Smart Search rates how each company's information relates to geothermal consultants: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#CompanyRevenueBase Smart SearchHeadquartersEmployeesContacts
1Indirect evidenceOlathe, KS, United StatesHQ checked Sep 20, 20265,001-10,0006,113 contacts →

Indirect evidence

“Terracon is a 100 percent employee-owned consulting engineering firm providing quality services to clients.”

Source: RevenueBase Database · checked Sep 20, 2026
2Indirect evidenceChantilly, VA, United StatesHQ checked Sep 20, 20261,001-5,0002,210 contacts →

Indirect evidence

“ECS Group of Companies is a Chantilly, VA-based consulting engineering firm.”

Source: RevenueBase Database · checked Sep 20, 2026
3Indirect evidenceParsippany, NJ, United StatesHQ checked Sep 20, 20261,001-5,0002,177 contacts →

Indirect evidence

“Langan's client-focused, highly entrepreneurial culture cultivates an environment of opportunities in which career growth and teamwork flourish.”

Source: RevenueBase Database · checked Sep 20, 2026
4Indirect evidenceTorrance, CA, United StatesHQ checked Sep 20, 20261,001-5,0001,358 contacts →

Indirect evidence

“Partner Assessment Corp.”

Source: RevenueBase Database · checked Sep 20, 2026
5Indirect evidenceReno, NV, United StatesHQ checked Sep 20, 20261,001-5,0001,281 contacts →

Indirect evidence

“With over five decades of experience, Ormat Technologies, Inc.”

Source: RevenueBase Database · checked Sep 20, 2026
6Indirect evidenceDenver, CO, United StatesHQ checked Sep 20, 20261,001-5,0001,231 contacts →

Indirect evidence

“Knight Piésold is an employee-owned, global consulting firm providing specialist services to the mining, power, water resources, and infrastructure industries.”

Source: RevenueBase Database · checked Sep 20, 2026
7Indirect evidenceMinneapolis, MN, United StatesHQ checked Sep 20, 20261,001-5,0001,088 contacts →

Indirect evidence

“Barr provides engineering and environmental consulting services to clients across the Midwest, throughout the Americas, and around the world.”

Source: RevenueBase Database · checked Sep 20, 2026
8Partial evidenceNorwood, MA, United StatesHQ checked Sep 20, 2026501-1,000880 contacts →

Partial evidence

“Founded in 1964 as a soils and foundations specialty consultant, GZA GeoEnvironmental, Inc.(GZA) has grown into a full-service company providing its clients with highly…”

Source: RevenueBase Database · checked Sep 20, 2026
9Indirect evidenceAnaheim, CA, United StatesHQ checked Sep 20, 20261,001-5,000851 contacts →

Indirect evidence

“Willdan (NASDAQ: WLDN) provides professional consulting and technical services to utilities, public agencies and private industry throughout the United States.”

Source: RevenueBase Database · checked Sep 20, 2026
10Indirect evidenceNew York, United StatesHQ checked Sep 20, 2026501-1,000803 contacts →

Indirect evidence

“Consult Engineer Commission At Syska Hennessy Group, we create exceptional environments.”

Source: RevenueBase Database · checked Sep 20, 2026
11Indirect evidencePortland, OR, United StatesHQ checked Sep 20, 2026201-500744 contacts →

Indirect evidence

“PAE provides mechanical and electrical engineering design, technology system design, energy modeling and analysis, and more.”

Source: RevenueBase Database · checked Sep 20, 2026
12Indirect evidenceSan Antonio, TX, United StatesHQ checked Sep 20, 2026501-1,000582 contacts →

Indirect evidence

“Founded in 1968, Raba Kistner Inc.”

Source: RevenueBase Database · checked Sep 20, 2026
13Partial evidenceLongview, TX, United StatesHQ checked Sep 20, 2026501-1,000578 contacts →

Partial evidence

“Since 1991, Applied Consultants Inc.”

Source: RevenueBase Database · checked Sep 20, 2026
14Indirect evidenceLaramie, WY, United StatesHQ checked Sep 20, 2026501-1,000577 contacts →

Indirect evidence

“Headquartered in Laramie, Wyoming, Trihydro provides environmental consulting, engineering and surveying, air quality and process management, information technology, and water and…”

Source: RevenueBase Database · checked Sep 20, 2026
15Indirect evidenceBoston, MA, United StatesHQ checked Sep 20, 2026201-500545 contacts →

Indirect evidence

“Vanderweil is a mechanical, electrical, plumbing, fire protection, technology, sustainability, commissioning, and power engineering firm dedicated to providing customized and…”

Source: RevenueBase Database · checked Sep 20, 2026
16Indirect evidenceHouston, TX, United StatesHQ checked Sep 20, 2026201-500521 contacts →

Indirect evidence

“SAExploration offers a full range of geophysical ground acquisition services from design, prospecting, drilling, recording and analysis of field quality, as well as mobilization…”

Source: RevenueBase Database · checked Sep 20, 2026
17Indirect evidenceKennesaw, GA, United StatesHQ checked Sep 20, 2026501-1,000518 contacts →

Indirect evidence

“Established in 1996, NOVA was originally founded to provide Environmental Consulting, Geotechnical Engineering, and Construction Materials Testing and Inspection services to the…”

Source: RevenueBase Database · checked Sep 20, 2026
18Indirect evidenceRound Rock, TX, United StatesHQ checked Sep 20, 2026201-500494 contacts →

Indirect evidence

“RRC is a top-tier designer of utility-scale wind, solar, energy storage, data center, and oil & gas projects in the US and select international markets.”

Source: RevenueBase Database · checked Sep 20, 2026
19Indirect evidenceRedmond, WA, United StatesHQ checked Sep 20, 2026201-500479 contacts →

Indirect evidence

Source: RevenueBase Database · checked Sep 20, 2026
20Indirect evidenceHouston, TX, United StatesHQ checked Sep 20, 2026n/a470 contacts →

Indirect evidence

Source: RevenueBase Database · checked Sep 20, 2026
21Indirect evidenceSan Francisco, CA, United StatesHQ checked Sep 20, 2026201-500386 contacts →

Indirect evidence

“Glumac, a Tetra Tech Company, is a global leader in building engineering, committed to delivering a low carbon future for all.”

Source: RevenueBase Database · checked Sep 20, 2026
22Indirect evidenceLong Beach, CA, United StatesHQ checked Sep 20, 2026201-500375 contacts →

Indirect evidence

“P2S has brought forward-thinking, sustainable engineering solutions to California, the Pacific Northwest, and beyond, for over 30 years.”

Source: RevenueBase Database · checked Sep 20, 2026
23Indirect evidenceParlin, NJ, United StatesHQ checked Sep 20, 2026201-500336 contacts →

Indirect evidence

“CME Associates, with eight (8) office locations throughout New Jersey, provides a complete range of Environmental, Geotechnical, Engineering, Surveying and Planning services.”

Source: RevenueBase Database · checked Sep 20, 2026
24Indirect evidencePark Ridge, NJ, United StatesHQ checked Sep 20, 2026201-500336 contacts →

Indirect evidence

“National Utility Service, Inc.”

Source: RevenueBase Database · checked Sep 20, 2026
25Indirect evidenceRichmond, VA, United StatesHQ checked Sep 20, 2026201-500312 contacts →

Indirect evidence

“Established in 1881, Froehling & Robertson, Inc.”

Source: RevenueBase Database · checked Sep 20, 2026

Showing 25 of 3,831 geothermal consultants based in the United States

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Geothermal consultants based in the United States at a glance

As of Sep 20, 2026
46.3%Verified-email coverage
19.8Average contacts per company
1-10Median size (employees)
6.1%Largest-city concentration · Houston
Sep 20, 2026Page data refreshed

Companies by employee count

1-10
2,088
11-50
1,250
51-200
388
201-500
64
501-1,000
13
1,001-5,000
19
5,001-10,000
3
10001+
2

Email recency for this list is measured worldwide rather than for United States, so it is reported there. Company counts and contact totals on this page are exact for United States, over 3,831 companies.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among geothermal consultants, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source
The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
What qualifies
Companies headquartered in the United States whose own description of what they do matches “geothermal consultants”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search
RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names geothermal consultants), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude
Companies whose own description does not clearly place them among geothermal consultants, and records with no verified work email. Companies headquartered outside United States are excluded even when they keep an office there.
Match quality
In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking
Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification
Every listed company carries at least one verified work email, 35,143 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh
This page's figures were pulled from the company graph on September 20, 2026. Lists refresh periodically as the graph is re-checked.
Corrections
Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names geothermal consultants, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many geothermal consultants are there based in the United States?

RevenueBase identified 3,831 geothermal consultants headquartered in the United States as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Terracon, headquartered in Olathe, tops this list with the largest team on record.

Which city has the most geothermal consultants?

Houston leads with 232 headquartered companies, followed by Denver (77) and Austin (57).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 35,143 verified decision-maker contacts tracked across these 3,831 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 20, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.