Bloom Energy and the Energy Server

This morning, the new company Bloom Energy, headed by founder and CEO KR Sridhar, Ph.D, launched their new business based on their new patented energy generation technology with hopes of revolutionizing the energy market.  Dubbed the “bloom box”, the bloom box is composed of a patented solid oxide fuel cell technology developed by Dr. Sridhar and Bloom Energy. To gain a better understanding of this technology, let’s first discuss solid oxide fuel cells (source).

Solid Oxide Fuel Cells

Fuel cells have been around for the last century. Early forms of fuel cells including proton exchange membranes, phosphoric acid fuel cells, and molten carbonate fuel cells have all been too inefficient to consider as all require expensive precious metals, corrosive acids or hard to contain molten materials. These materials are all expensive and with the amount of gain compared to the other options on the market, they have never been economically viable. Fuel cells also produce a large amount of heat energy as a byproduct. Researchers started to try to harness this wasted heat energy by developing combined heat and power (CHP) schemes however these to seemed to prove economically inefficient in the majority of cases.

Solid Oxide fuel cells, however, use low-cost ceramics and highly efficient electrical material to increase their economic efficiency. Because they operate at such high temperatures (800 deg C), this allows for the solid oxide fuel cell to no longer need the precious metals required by other forms of fuel cells. The fuel cell is composed of three layers; an anode, electrolyte, and a cathode. A fuel source is then pumped into the anode layer and air into the cathode layer. In the electrolyte, a chemical reaction takes place and electrons are moved, generating an electric current. Byproducts are also expelled from the other two layers. These fuel cells have estimated efficiencies of 50-60% and when the waste heat is reused, the efficiency reaches ranges of 80-85% (source)

Diagram: How a Solid Oxide Fuel Cell (SOFC) works. An AFC consists of a non-porous metal oxide electrolyte (typically zirconium oxide) sandwiched between an anode (negatively charged electrode) and a cathode (positively charged electrode). The processes that take place in the fuel cell are as follows: 1. Hydrogen fuel is channeled through field flow plates to the anode on one side of the fuel cell, while oxygen from the air is channeled to the cathode on the other side of the cell.  2. At the cathode, a catalyst causes electrons from the electrical circuit to combine with oxygen to create negatively charged oxygen ions. 3. The negatively charged oxygen ions flow through the electrolyte to the anode. 4. At the anode, the catalyst causes the hydrogen to react with the oxygen ions forming water and free electrons. 5. The negatively charged electrons cannot flow through the electrolyte to reach the positively charged cathode, so they must flow through an external circuit, forming an electrical current. 6. At the cathode, the electrons combine with oxygen to create negatively charged oxygen ions, and the process repeats.


Bloom Energy’s Design

Bloom Energy, through research in materials sciences and engineering, has developed a patented new solid oxide fuel cell. The anode and cathode layers are comprised of specially formulated inks where as the electrolyte is a thin sheet of ceramic created from beach sand. Fuel enters on the anode side and then combines with steam to form the another type of fuel that is then applied to the anode. On the other side, heated air, more importantly, heated oxygen is placed on the cathode side. When the heated oxygen and fuel meet at the electrolyte, a chemical reaction takes place. In Bloom Energy’s case, the reaction is stated to be:

CH4 + 2O2 —› CO2 + 2H2O + e- + heat

The electrons then flow from the oxygen molecules through the electrolyte and generate electricity. The CO2 is released on the anode side and the water is then reused to form the steam required to mix with the fuel. The heat generated from the reaction is also reused to heat the incoming oxygen for the process to take place. As long as there is fuel, air, and heat, the process will continuously take place. To see an animated version of the process along with an explanation please click here.


Bloom Energy has created fuel cells that are small in size, yet are capable of producing around 25 watts of power, which is enough to power a light bulb. When these fuel cells are combined into stacks with metal layers, they form what is called a “bloom box”. A bloom box is capable of producing one kilowatt of power. It is enough to where two bloom boxes alone could be enough to power an average American home at its base load. Groups of these bloom boxes are then combined into a large unit called and energy server. These energy servers are capable of producing 100 kW of power. Bloom Energy posted a spec sheet for one of their patented energy servers and it is given below.

Technical Highlights
Fuels Natural Gas, Directed Biogas
Input fuel pressure 15 psig
Fuel required @ rated power 0.661 MMBtu/hr of natural gas
Water required (for startup only) 120 gallons municipal water
Rated power output (AC) 100 kW
Electrical efficiency (LHV net AC) > 50%
Electrical connection 480V @ 60 Hz, 4-wire 3 phase
Weight 10 tons
Size 224″ x 84″ x 81″
NOx < 0.07 lbs/MW-hr
SOx negligible
CO < 0.10 lbs/MW-hr
VOCs < 0.02 lbs/MW-hr
CO2 @ specified efficiency 773 lbs/MW-hr on natural gas,
carbon neutral on Directed Biogas
Standard temperature range 0° to 40° C (extreme weather kit available)
Max altitude at rated power 6,000 ft. MSL
Humidity 20% – 95%
Seismic Vibration IBC 2003: Site Class D
Location Outdoor
Noise @ rated power < 70 DB @ 6 feet
Codes and Standards
Complies with Rule 21 interconnection standards
Exempt from CA Air District permitting; meets stringent CARB 2007 emissions standards
Product Listed by Underwriters Laboratories (UL) to the FC-1 standard
Additional Notes
Operates in a grid parallel configuration
Includes a secure website for you to showcase performance & environmental benefits
Remotely managed and monitored by Bloom Energy
Capable of emergency stop based on input from your facility


Layout of the ES-5000


These energy servers as can be seen above are very large yet have the capability of producing large amounts of power. They are capable of running on either natural gas or bio gas as can be read from the spec sheet.  These are ideal for large corporations who have many large buildings to power. In fact, Bloom Energy has already deployed test units to customers who have been secretly trying the systems. Some of these big name companies include Google, Staples, Wal-Mart and eBay. In an interview with an eBay official done by CBS’ 60 Minutes, he claimed that int he past nine months, a handful of these energy servers saved a campus of eBay buildings in California over $100,000 alone. Similar results have been found by the other major companies. (To view the CBS interview video, please click here)

Perhaps the greatest aspect of these revolutionary energy servers is that they produce little to no pollution or green house gases. When used with natural gas, a slight amount of carbon is emitted. However, when used with bio gases, the carbon is simply recycled and therefor no carbon emissions occur or it is carbon neutral. Also, Bloom Energy is attacking the transmission sector. A large amount of energy is lost in the transmission from the power plant to the home and business sectors. With the energy server, electricity is generated on sight and therefore the transmission of the electricity is completely eliminated along with the inefficiencies that it brings with it. Bloom Energy hopes to one day replace the entire energy grid with on site electricity generation. As also can be seen from the 60 Minutes stories, many big names have stated their support in Bloom Energy’s energy severs. Colin Powell stated his views in the story as saying that though it may not be an absolute answer to our energy needs, it is defiantly a viable solution to aid in the change over to clean energy technologies (source).

Bloom Energy’s energy server is a brand new technology and like all new technologies, it  shows promise. However, I am still personally skeptical at this new innovation.  Only time will tell if this new revolutionary technology is efficient enough to be a leading aid in our transition to cleaner energy.



Filed under energy

2 responses to “Bloom Energy and the Energy Server

  1. msp746

    I agree with your skeptism towards Bloom Energy. The technology sounds fantastic, but many other companies have tried the fuel cell path and have not lived up to expectations. I see two down sides of the technology that are not emphasized enough. First, it still has disadvantages on the economic front and is not as carbon neutral as hoped. On the economic front, currently half the cost is subsidized by the government, with 20% of the cost subsidized by the California state government and 30% by the federal government, with Bloom Energy calculating a payback of 3 to 5 years including the subsidies. Others calculate the payback period without the subsidies as closer to 15 years without including connection costs and assuming an efficiency of 80%. A length of 15 years is closer to other renewable sources currently available. Second, their technology can only be carbon neutral if its uses biogas as its fuel source. The supply of biogas is quite limited and has trouble being shipped around. Natural gas will thus primarily be the fuel of choice, which is not carbon neutral. Moreover, the customer is still exposed to natural gas price fluctuations. In the end, I hope Bloom Energy can scale their manufacturing process and achieve the price points and reliability they promote, because even using natural gas, it is claimed to be 50% more efficient than using large electricity plants.’s-carbon-neutral-claim-relies-on-scarce-biogas/

  2. bhgully

    You both raise very important points with regard to what is likely to be one of the most useful recent technological developments (SOFC) – creating a very informative blog. The flexibility in fuel sources I believe is one of the most powerful aspects of these types of fuel cells, particularly the capability to utilize syngas – potentially offering an avenue for efficiently utilizing numerous waste stream energy sources. Will be a good one to watch, that’s for sure…

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